Genetics and human behaviour - the ethical context 9781904384038, 1-904384-03-X

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Genetics and human behaviour the ethical context

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Genetics and human behaviour: the ethical context

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Nuff ield Council on Bioet hics Prof essor Sir Ian Kennedy (Chairman) Prof essor M art in Bobrow CBE (Deput y Chairman) Prof essor Tom Baldw in M s Rebecca Burke CBE Prof essor Sir Kennet h Calman KCB FRSE The Rt Rev Richard Harries DD FKC FRSL Prof essor Bob Hepple QC Prof essor John Ledingham Prof essor Cat herine Peckham CBE Prof essor M art in Raff M r Nick Ross Prof essor Herbert Sew ell Prof essor Dame M arilyn St rat hern FBA Prof essor Albert Weale FBA Dr Alan Williamson FRSE

Secretariat Dr Sandy Thomas (Direct or) M s Tor Lezemore M s Susan Bull (unt il April 2002) M r Harald Schmidt (f rom M ay 2002) M rs Julia Fox M s Yvonne M elia (unt il April 2002) M s Nat alie Bart le (f rom June 2002) M s Nicola Perrin M s Elaine Talaat -Abdalla M s M aria Gonzalez-Nogal

The terms of reference are as follow s: 1 t o ident if y and def ine et hical quest ions raised by recent advances in biological and medical research in order t o respond t o, and t o ant icipat e, public concern; 2 t o make arrangement s f or examining and report ing on such quest ions w it h a view t o promot ing public underst anding and discussion; t his may lead, w here needed, t o t he f ormulat ion of new guidelines by t he appropriat e regulat ory or ot her body; 3 in t he light of t he out come of it s w ork, t o publish report s; and t o make represent at ions, as t he Council may judge appropriat e.

The Nuffield Council on Bioethics is funded jointly by the M edical Research Council, the Nuffield Foundation and the Wellcome Trust

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Pref ace I was apprehensive when asked by the Nuffield Council on Bioethics to chair the Working Party which has produced this Report. First, because the subject has an ugly history: within living memory perverted science was put at the service of ideologies that led to the subjugation and even extermination of people judged to be genetically ‘inferior’. Secondly, because modern behavioural genetics is rich in promise but, as yet, poor in hard verifiable evidence. Thirdly, because it seemed unlikely that one would be able to reach any agreed recommendations in this highly complex and controversial field. All t hese f ears have been dispelled over t he past t w o years in w hich t he Working Part y has met eleven t imes, held six f act -f inding sessions w it h more t han t w ent y expert s, commissioned review s of t he scient if ic evidence, and undert aken a public consult at ion. It became clear t hat t his invest igat ion, believed t o be t he f irst of it s kind, is necessary if w e w ant t o avoid t he mist akes of t he past , make an impart ial assessment of t he emerging scient if ic evidence, and reach valid moral and legal conclusions about t he pot ent ial applicat ions of t he research. The agreed recommendat ions are import ant , but perhaps even more signif icant are t he caref ul explanat ion t hat w e have at t empt ed t o give of t he met hods of research in t his area, t he assessment of t he current evidence f or genet ic inf luences on behaviour, and t he balanced discussion of t he et hical and legal choices t hat lie ahead. Our expect at ion is t hat t his Report w ill help non-specialist s t o underst and w hat behavioural genet ics aspires t o achieve, w hat has t hus f ar been achieved and equally import ant ly, how much has not yet been achieved. We hope t hat it w ill promot e an inf ormed debat e bet w een scient ist s, policy makers, and t he lay public about t he et hical and legal implicat ions. I should like to thank the members of the Working Party for their hard work and dedication; working with them was an enjoyable and stimulating experience. We are all grateful to Dr Sandy Thomas, Director of the Nuffield Council on Bioethics, for her guidance and sound judgment. Tor Lezemore made a truly outstanding contribution as our inventive scribe, editor and secretary; her sparkling humour and enthusiasm kept us going. Thanks are also due to Julia Fox, Yvonne Melia, Susan Bull, Natalie Bartle and Nicola Perrin for their support. Finally, since this is the last Report which will be published under Sir Ian Kennedy’s chairmanship of the Nuffield Council on Bioethics, I should like to pay tribute to his enormous contribution to bioethics in general, and to his role as mentor of this Working Party in particular.

Bob Hepple QC

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Acknow ledgement s The Working Part y w ishes t o t hank t he many organisat ions and individuals w ho have assist ed it s w ork, part icularly t hose w ho at t ended f act -f inding meet ings or submit t ed responses t o t he public consult at ion. The Working Part y is very grat ef ul t o Prof essor Sir Robert Hinde, Prof essor Erik Parens, Prof essor Nikolas Rose, Tim Radf ord and Prof essor Sir M ichael Rut t er, w ho all review ed an earlier draf t of t he Report . Their comment s cont ained const ruct ive crit icisms and suggest ions f or f urt her discussion, w hich w ere ext remely helpf ul. The Working Part y w ould like t o t hank t he f ollow ing individuals f rom w hom it commissioned papers review ing t he scient if ic evidence in research in behavioural genet ics: Prof essor John Crabbe, Prof essor Jeff ery Gray, Prof essor Nicholas M ackint osh and Prof essor Terrie M off it t . The Working Part y is also grat ef ul t o individuals w ho responded t o request s f or advice on specif ic part s of t he Report , including Dr Jonat han Flint , M rs Nicola Padf ield and Prof essor M ark Rot hst ein.

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Genet ics and human behaviour: t he et hical cont ext Table of Contents Council membership and terms of reference .................................................................... iii Preface ................................................................................................................................... v Acknow ledgements............................................................................................................. vi Working Party membership .............................................................................................. xiii Working Party terms of reference ..................................................................................... xv Summary and recommendations...................................................................................... xix

Section I: Introduction and context Chapter 1: Introduction ........................................................................................................ 3

Why t his Working Part y is import ant .................................................................................. 5 Def ining t he normal range of behavioural charact erist ics................................................ 7 The scope of research in behavioural genet ics .................................................................. 8 The st ruct ure of t he Report ................................................................................................. 8 Chapter 2: The historical context ...................................................................................... 11

The impact of eugenic t hought on research int o human behaviour ............................. 18 Psychology in t he f irst half of t he t w ent iet h cent ury .......................................... 18 Psychology f rom t he 1960s onw ards...................................................................... 20 Individual diff erences ............................................................................. 20 Evolut ionary psychology......................................................................... 21 Processes of development ...................................................................... 21 Conclusion ........................................................................................................................... 22

Section II: Scientific background Chapter 3: Research in behavioural genetics ................................................................... 25

Int roduct ion ........................................................................................................................ 27 What is genet ic variat ion?................................................................................................. 29 What is meant by normal variat ion in human behaviour?............................................. 31 ‘A gene f or X’? ................................................................................................................... 32 Describing human behaviour ............................................................................................ 35 Predict ing human behaviour f rom genet ic inf ormat ion ................................................. 35 Conclusion ........................................................................................................................... 36 Chapter 4: Quantitative genetics: measuring heritability .............................................. 37

Int roduct ion ........................................................................................................................ 39 How is populat ion variat ion examined using genet ic st udies?....................................... 39 Genet ic inf luences on variat ion.............................................................................. 39 vii

Environment al inf luences on variat ion .................................................................. 41 Gene-environment correlat ion and int eract ion .................................................... 41 Family, t w in and adopt ion st udies..................................................................................... 42 Family st udies........................................................................................................... 42 St udies of t w ins........................................................................................................ 42 M et hods................................................................................................... 42 Int erpret at ion of t w in st udy f indings.................................................... 43 Adopt ion st udies................................................................................................................. 44 Current uses of quant it at ive genet ic st udies.................................................................... 45 Conclusion ........................................................................................................................... 46 Chapter 5: Identifying genetic factors contributing to individual differences in behaviour . 47

Int roduct ion ........................................................................................................................ 49 Approaches t o ident if ying suscept ibilit y alleles............................................................... 49 Linkage st udies........................................................................................................ 50 Associat ion st udies .................................................................................................. 51 Ident if icat ion of alleles t hat inf luence behaviour ................................................ 52 Scaling up t he analysis: new met hods in genet ics................................................ 52 Conclusion ........................................................................................................................... 53 Chapter 6: Research in behaviour genetics involving animals ...................................... 55

Int roduct ion ........................................................................................................................ 57 How are animal models creat ed?...................................................................................... 58 What are t he benef it s of using animals t o st udy t he genet ics of human behaviour?.. 60 What are the problems with using animals to study the genetics of human behaviour? .. 61 Conclusion ........................................................................................................................... 63

Part III: Review s of the evidence Chapter 7: Intelligence ....................................................................................................... 67

Background ......................................................................................................................... 69 Trait def init ion and measurement .................................................................................... 69 Current f indings: quant it at ive genet ics............................................................................ 71 Current f indings: molecular genet ics................................................................................ 73 Direct ions f or f ut ure research ........................................................................................... 76 Chapter 8: Personality ........................................................................................................ 79

Background.......................................................................................................................... 81 Trait def init ion and measurement .................................................................................... 81 Current f indings: quant it at ive genet ics............................................................................ 83 Current f indings: molecular genet ics................................................................................ 84 Quant it at ive t rait loci research............................................................................... 85 Current f indings: research involving animals................................................................... 85 Fut ure direct ions f or research ........................................................................................... 86

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Chapter 9: Antisocial behaviour ........................................................................................ 87

Background ......................................................................................................................... 89 Trait def init ion and measurement .................................................................................... 89 Current f indings: quant it at ive genet ics............................................................................ 91 Ant isocial behaviour................................................................................................ 91 Violence.................................................................................................................... 93 Sex diff erences......................................................................................................... 94 Current f indings: molecular genet ics................................................................................ 95 Current f indings: research involving animals................................................................... 95 Fut ure direct ions f rom research ........................................................................................ 96 Chapter 10: Sexual orientation ......................................................................................... 97

Background ......................................................................................................................... 99 Trait measurement and def init ion .................................................................................... 99 Current f indings: quant it at ive genet ics.......................................................................... 100 Families

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Tw ins and adopt ed siblings .................................................................................. 101 M ale homosexualit y ............................................................................. 101 Female homosexualit y.......................................................................... 102 Current f indings: molecular genet ics.............................................................................. 102 Current f indings: research involving animals................................................................. 103 Current f indings: ot her biological inf luences................................................................. 104 Crit ical assessment of t he validit y of t his evidence.........................................................105 Evolut ionary argument s against genet ic inf luences on homosexualit y ....................... 106 Fut ure direct ions f or research ......................................................................................... 107 Chapter 11: Themes from the review s of the evidence ................................................ 109

Int roduct ion ...................................................................................................................... 111 The diff icult y of def ining and measuring t rait s............................................................. 111 Est imat es of herit abilit y ................................................................................................... 111 The lack of replicat ed f indings in molecular genet ics................................................... 112 Applicat ions of current research f indings....................................................................... 112 Report ing research in behavioural genet ics................................................................... 113 Funding research in behavioural genet ics...................................................................... 114 Conclusion ......................................................................................................................... 115

Part IV: Ethical, legal, social and policy issues Chapter 12: Genetics, freedom and human dignity ...................................................... 119

The mat erial self ............................................................................................................... 122 Det erminism and f at alism ................................................................................................ 123 Freedom, possibilit y and rat ionalit y................................................................................ 124 Eliminat ing rat ionalit y .......................................................................................... 125 Accommodat ing rat ionalit y.................................................................................. 126

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The implicat ions of behavioural genet ics....................................................................... 128 Conclusion ......................................................................................................................... 130 Chapter 13: Selecting and changing behavioural traits............................................... 131

Int roduct ion ...................................................................................................................... 133 Will t here be any pract ical applicat ions of research in behavioural genet ics ............. 133 Genet ic int ervent ions............................................................................................ 134 M edical int ervent ions............................................................................................ 135 Environment al int ervent ions................................................................................ 135 ‘M edicalising’ human behaviour ..................................................................................... 135 St igma................................................................................................................................ 139 Evaluat ing diff erent w ays of changing ourselves.......................................................... 140 Eff ect iveness........................................................................................................... 140 Saf et y ..................................................................................................................... 140 Reversibilit y............................................................................................................ 142 Choice .................................................................................................................... 142 Int ervent ion and individualit y.............................................................................. 143 Therapy versus enhancement .............................................................. 144 Access t o int ervent ions..................................................................................................... 145 M onit oring t he provision of genet ic t est s and int ervent ions....................................... 146 Prenat al select ion ............................................................................................................. 148 Technologies f or prenat al t est ing and select ion ................................................. 148 Select ion on non-clinical grounds: et hical argument s ....................................... 150 For select ion .......................................................................................................... 152 The right t o procreat ive aut onomy..................................................... 152 Against select ion ................................................................................................... 153 The ‘expressivist ’ argument .................................................................. 153 Equalit y.................................................................................................. 153 Nat ural humilit y.................................................................................... 154 Chapter 14: Legal responsibility ..................................................................................... 157

The hist ory of biological explanat ions of human behaviour in law ............................. 159 Previous genet ic and physiological explanat ions of crime............................................ 160 XYY males.............................................................................................................. 160 Syndromes.............................................................................................................. 161 Genet ics: Hunt ingt on’s disease............................................................................. 161 Genet ics: M onoamine oxidase A (M AOA) def iciency ......................................... 161 Genet ic inf ormat ion as an exculpat ory f act or ............................................................... 162 Sent encing and t reat ment of off enders......................................................................... 166 Predict ive use of genet ic inf ormat ion............................................................................. 168 Conclusion ......................................................................................................................... 171

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Chapter 15: Testing and selection in employment, education and insurance ........... 173

Employment ...................................................................................................................... 177 The current legal f ramew ork................................................................................ 177 Discriminat ion law s ............................................................................................... 178 Unf air dismissal ...................................................................................................... 180 Privacy and conf ident ialit y ................................................................................... 180 Earlier ref orm proposals ....................................................................................... 181 Test ing f or behavioural t rait s............................................................................... 182 Educat ion .......................................................................................................................... 183 Insurance .......................................................................................................................... 185 Appendix 1: M et hods of w orking ................................................................................... 191 Appendix 2: Consult at ion w it h t he public...................................................................... 195 Glossary ............................................................................................................................. 205 Glossary of Abbreviat ions and Acronyms....................................................................... 211 Index .................................................................................................................................. 213

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Genet ics and human behaviour: t he et hical cont ext M embers of the Working Party Prof essor Bob Hepple QC (Chairman) M ast er, Clare College, Cambridge Prof essor M art in Bobrow CBE Head of Depart ment of M edical Genet ics, Universit y of Cambridge Deput y Chairman of t he Nuff ield Council on Bioet hics Prof essor Tom Baldw in Head of Depart ment of Philosophy, Universit y of York M ember of t he Nuff ield Council on Bioet hics Prof essor Annet t e Karm iloff -Sm it h Head of Neurocognit ive Development Unit Inst it ut e of Child Healt h, Universit y College London Prof essor Sandy M cCall-Sm it h Prof essor of M edical Law, Universit y of Edinburgh Prof essor Terrie M off it t Social, Genet ic and Development al Psychiat ry Research Cent re Inst it ut e of Psychiat ry, King’s College London Dr Paul Pharoah CRC Senior Clinical Research Fellow St rangew ays Research Laborat ories, Cambridge Prof essor Nicholas Raw lins Prof essor of Behavioural Neuroscience, Universit y of Oxf ord Prof essor M art in Richards Cent re f or Family Research, Universit y of Cambridge M r Pushpinder Saini Blackst one Chambers, Temple Dr Tom Shakespeare Policy, Et hics and Lif e Sciences Research Inst it ut e, Int ernat ional Cent re f or Lif e, New cast le Prof essor Anit a Thapar Prof essor of Child and Adolescent Psychiat ry, Universit y of Wales College of M edicine Prof essor Andrew Wilkie Wellcome Senior Clinical Fellow, Honorary Consult ant in M edical Genet ics, Inst it ut e of M olecular M edicine, Universit y of Oxf ord

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Genet ics and human behaviour: t he et hical cont ext Terms of reference 1 To def ine and consider et hical, social and legal issues arising f rom t he st udy of t he genet ics of variat ion w it hin t he normal range of behavioural charact erist ics.1 2 To survey t he current f ield of research, in part icular, t o review : a t he evidence f or t he relat ive import ance of genet ic inf luences; b t he basis f or charact erisat ion and measurement of behaviour; c t he relat ionship bet w een normal variat ion in behaviour and disease processes. 3 To consider pot ent ial applicat ions of t he research. 4 To consider: a t he et hics of undert aking research on t he genet ics of normal variat ion in behavioural charact erist ics2 on human part icipant s;3 b t he implicat ions of applying t he f indings of such research t hrough t he development of genet ic t est s t o est ablish part icular charact erist ics in pract ical cont ext s including educat ion, employment , insurance, legal proceedings; c t he part icular impact of t he f indings of a genet ic t est on t he individual, including an individual child or f et us, on f amily members, and on various social groups; d t he broader impact of genet ic know ledge on t he percept ion of t hose w it h relevant behavioural charact erist ics, including quest ions about st igma.

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And t o ident if y t he issues w hich are addit ional or complement ary t o t hose dealt w it h in t he Council's Report : M ent al disorders and genet ics: t he et hical cont ext .

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Including, f or example, research on int elligence, ant isocial behaviour, sexual orient at ion and addict ion.

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Including et hnic groupings, criminal off enders and children.

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Summary and recommendations

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

RECO M M EN D ATI O N S

If genes t hat inf luence part icular behavioural t rait s are ident if ied, it could become possible t o t est f or t he presence of variat ions in t hese genes in individual people. No such t est s current ly exist . M oreover, t here is disagreement about w het her t est s t hat predict human behaviour accurat ely could ever be developed. But even if genet ic t est s could not yield predict ions of a def init e out come, it may nonet heless be possible t hat t est s t hat suggest an individual w ill have an increased chance of possessing a part icular t rait t o a great er or lesser degree might be developed. Such hypot het ical t est s might be undert aken f or a variet y of purposes. One purpose w ould be simply t o gain more know ledge about t he inf luence of genes on behaviour. Anot her purpose might be t hat of int ervent ion or t reat ment , f or example t o prevent aggressive behaviour by using medicines, or by at t empt s t o change relevant aspect s of t he environment . A f urt her purpose might be t hat of select ion. This encompasses, f or inst ance, prenat al t est ing, t he st reaming of children in schools on t he basis of int elligence and apt it ude, t he screening of employees and jobseekers t o exclude t hose w it h t rait s t hat employers consider undesirable, and t he use by insurers of genet ic inf ormat ion about behaviour and personalit y t rait s in order t o est imat e risk. Yet anot her purpose might be t o claim diminished legal responsibilit y f or one’s act ions or t o mit igat e punishment f or criminal behaviour.

A N D

Human behaviour is influenced both by the genes that we inherit and the environment in which we live. With the significant advances in our knowledge of genetics and publication of the draft sequence of the human genome, the focus of research has moved once again towards understanding the biological contribution to behaviour.1 Some researchers are attempting to locate specific genes, or groups of genes, associated with behavioural traits and to understand the complex relationship between genes and the environment. This is called research in behavioural genetics. In contrast to research into the genetic basis of diseases and disorders, researchers in behavioural genetics investigate aspects of our personalities such as intelligence, sexual orientation, susceptibility to aggression and other antisocial conduct, and tendencies towards extraversion and novelty-seeking.

SU M M A RY

Summary and recommendat ions

In 1999, t he Nuff ield Council on Bioet hics agreed t hat it w as import ant t o ant icipat e t he et hical, legal and social implicat ions raised by research in behavioural genet ics. Previous w ork by t he Council and ot her groups has f ocused on inherit ed disease and suscept ibilit y t o clinical disorders. This Report is int ended t o f ill t hat gap and t o draw at t ent ion t o t he implicat ions of research in genet ics w hich f alls out side t he medical sphere. The object ives of t he Working Part y est ablished by t he Council in 2000 w ere t o def ine and consider t he et hical, legal and social issues arising f rom t he st udy of t he genet ics of variat ion w it hin t he normal range of behaviour charact erist ics. The subject of t his Report is human behaviour w it hin t he normal range, as opposed t o t rait s t hat are def ined as illnesses or diseases. An import ant preliminary quest ion is w het her it is act ually f easible t o t alk about a ‘normal range’ of behavioural t rait s. There is a danger t hat , in speaking of t he ‘normal’ range, t his Report may be misunderst ood as st igmat ising cert ain kinds of behaviour, namely t hose t hat are at t he ext remes of variat ion. It t heref ore needs t o be emphasised t hat w hen w e use t he phrases ‘normal variat ion’ or ‘behaviour in t he normal range’, no moral evaluat ion or judgement is implied. In t hese phrases, ‘normal’ has a st at ist ical meaning – it ref ers t o t he range of variat ion, usually t hat w hich includes about 95% of t he populat ion, and

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See f or example Dust er, T. (1990). Backdoor t o Eugenics. New York: Rout ledge. This account report s a subst ant ial rise, during t he 1980s, in t he publicat ion of scient if ic art icles t hat at t empt t o explain t he genet ic basis of behavioural t rait s.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

w hich is t hought not t o cont ain any individuals w it h clinical disorders or diseases. There are ot her approaches t o def ining normal behaviour. They include t he t heory t hat abnormal behaviour is t hat w hich result s in impaired f unct ion in societ y f or t he individual, eit her f rom t he individual’s ow n perspect ive, or f rom an object ive st andpoint , regardless of w het her t he behaviour is st at ist ically rare or not . We t ake t he st at ist ical approach merely as our st art ing point , using it t o limit t he f ield of inquiry. We have f ocused on t rait s, such as int elligence, t hat are cont inuously dist ribut ed measures, displayed by each individual in t he populat ion t o a great er or lesser ext ent , and w hich are not commonly view ed as disorders. The Report is divided int o t hree part s. The f irst part of t he Report explains t he hist orical and scient if ic background t o research in t he f ield of behavioural genet ics. Chapt er 2 out lines t he hist ory of t he eugenics movement and it s prof ound eff ect on t he development of clinical genet ics and development al psychology since t he Second World War. Chapt er 3 at t empt s t o explain w hat is meant by t he suggest ion t hat genes inf luence or aff ect human behaviour. There are diff erent w ays in w hich one can st udy t he cont ribut ion t hat genet ic f act ors make t o human behaviour. Chapt ers 4-6 explain t he diff erent met hods used by researchers in behavioural genet ics. The second part of t he Report , Chapt ers 7–11, cont ains review s of t he f indings t hat have been obt ained t o dat e in each of t hese met hods of research, w it h respect t o t he f ollow ing behavioural t rait s: int elligence, personalit y, ant isocial behaviour and sexual orient at ion. The principal t hemes t hat emerge f rom t he review s of t he evidence are summarised in Chapt er 11. The Report has been w rit t en so t hat readers not w ishing t o digest t he scient if ic inf ormat ion cont ained in t he review s of t he evidence can ref er t o Chapt er 11 inst ead, w it hout compromising t heir underst anding of t he Report . The t hird part of t he Report examines t he et hical, legal and policy issues and off ers a series of conclusions and recommendat ions. Chapt er 12 begins by discussing w het her t here is an inherent conf lict bet w een underst anding t he genet ic inf luences on behaviour and human dignit y, as it is expressed in t he concept s of f ree w ill and moral responsibilit y. Chapt er 13 t hen addresses some of t he pot ent ial applicat ions of t he research including genet ic, medical and environment al int ervent ions aimed at changing behavioural t rait s, as w ell as prenat al select ion. Chapt er 14 is concerned w it h t he implicat ions of research in behavioural genet ics f or t he criminal just ice syst em, in relat ion t o at t ribut ions of legal responsibilit y and sent encing, and in predict ing ant isocial behaviour. Chapt er 15 considers genet ic t est ing and select ion w it h regard t o educat ion, employment and insurance. The conclusions and recommendat ions f rom t he Report are summarised in t he remainder of t his sect ion.

Behavioural genetics and eugenics Eugenics has been a major social and political force in the twentieth century. Aspects of eugenic policies and practices, in particular, the violation of reproductive freedoms through the segregation and sterilisation of tens of thousands of people in the US, Europe and elsewhere, and the horrors of the ‘euthanasia’ programmes in Nazi Germany, have been widely, and correctly, condemned. Behavioural genet ics f ormed a major part of t he scient if ic f oundat ions on w hich eugenic policies w ere claimed t o be based and t he development of behavioural genet ics w as it self shaped by eugenic concerns. How ever, t his does not necessarily imply t hat cont emporary research on t he genet ics of behaviour is in any sense eugenic or is driven by considerat ions t hat could be considered eugenic. In f act , as w e have point ed out , part of t he reason f or t he decline in t he support of eugenic policies in many count ries f rom t he 1930s onw ard w as scient if ic research w hich demonst rat ed t hat t he policies of segregat ion and st erilisat ion of t hose deemed t o be unf it

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

There are diff erent w ays in w hich researchers can st udy t he cont ribut ion t hat genet ic f act ors make t o human behaviour. First , t here are observat ional st udies, w hich involve assessing and comparing relat ives such as t w ins or siblings, f amilies and adopt ed children. This t ype of research is called quant it at ive genet ics because it aims t o examine t he ext ent t o w hich variat ion in a t rait is inf luenced by genet ic f act ors in a populat ion. It uses st at ist ical met hods t o examine and compare groups of people, w it hout f ocusing on part icular genes (Chapt er 4). Secondly, researchers can t ry t o ident if y diff erences in genes t hat cont ribut e t o t rait variat ion in charact erist ics or t rait s bet w een individuals. This t ype of research is called molecular genet ics (Chapt er 5). Thirdly, researchers can use animals t o t ry and examine t he eff ect s of part icular genes on behaviour (Chapt er 6).

RECO M M EN D ATI O N S

The science of behavioural genetics

A N D

We conclude t hat hist orical and philosophical st udies of eugenic pract ices and policies should be encouraged so t hat it may be clearly underst ood w hat w as, and w as not , unaccept able about t he past and t he w ays in w hich t his may, or may not , be dist inguished f rom cont emporary genet ic policies and pract ices (paragraph 2.20).

SU M M A RY

w ould not achieve t heir st at ed goals. How ever, as a number of respondent s t o our consult at ion have suggest ed, t here remains a view t hat research on t he genet ics of human behaviour, part icularly in t he area of int elligence, is necessarily eugenic or w ill lead t o t he re-est ablishment of eugenic policies. It is possible t hat cont emporary underst anding of t he herit abilit y of IQ and ot her behavioural charact erist ics, and increasing know ledge of t he processes of inherit ance of ot her t rait s, could provide a scient if ic f oundat ion f or a programme of posit ive or negat ive eugenics, w ere t here t o be t he polit ical w ill or pow er t o const ruct and implement such a policy (paragraph 2.19).

It is common t o hear of research t hat claims t o ident if y a ‘gene f or aggression’ or a ‘gene f or homosexualit y’. But how could our genes cause us t o act in a part icular w ay? What is really meant by saying ‘a gene f or X’? The connect ion bet w een genes and diseases is f ar f rom st raight f orw ard, and t he relat ionship bet w een genes and behaviour is even more complicat ed. It is of t en diff icult t o est ablish w hich genes cont ribut e t o a t rait and how t hey do so because: ■ M ore t han one genet ic f act or usually cont ribut es t o a part icular t rait . ■ These mult iple genet ic f act ors may int eract w it h each ot her and have diff erent eff ect s depending on w hich ot her f act ors are present in t he individual’s genot ype. ■ As w ell as genet ic f act ors, many non-genet ic (environment al) f act ors may cont ribut e t o t he manif est at ion of a t rait . ■ These environment al f act ors may also int eract w it h each ot her. ■ The genet ic f act ors may aff ect w hich environment al f act ors have an eff ect . (This is called gene–environment int eract ion.) ■ Conversely, environment al f act ors may aff ect w hich genet ic f act ors have an eff ect . ■ Cert ain genet ic and environment al f act ors may go hand in hand. (This is called gene–environment correlat ion.) ■ A prot ein may be modif ied af t er it has been produced f rom a gene, and t his can alt er it s f unct ion. ■ Genes do not have a cont inuous eff ect in our bodies. They may be t urned on and off , bot h during our overall development and w it hin t he lif et ime of an individual cell. xxi

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So, w hile it might be correct t o say t hat a part icular genet ic variant is part of t he cause of a part icular t rait , or t hat it is one causal f act or, it w ill seldom be t he only cause, nor is it likely t o be eit her a necessary or suff icient condit ion f or t he t rait t o be manif est ed. Furt hermore, even if part icular genes t hat cont ribut e t o a t rait can be ident if ied, t his is only a small part of t he st ory. There is st ill a need t o underst and t he very indirect pat hw ay bet w een a gene, a part icular prot ein and an individual scoring highly on an IQ t est or having an aggressive personalit y. Our underst anding of t hese causal pat hw ays is at an even earlier st age t han our underst anding of w hich genes inf luence behavioural t rait s, w hich is it self ext remely limit ed (paragraphs 3.9 – 3.14).2 The complexit y of human behaviour and t he diff icult ies in underst anding how genes are involved may seem overw helming. There is w ide agreement t hat genes do have an indirect eff ect on behaviour. How ever, some comment at ors have suggest ed t hat any at t empt t o underst and t he processes by w hich genes inf luence behaviour w ill cert ainly f ail. We disagree. We consider t hat it is neit her a t heoret ical nor a pract ical impossibilit y t o ident if y genes t hat cont ribut e t o behavioural t rait s and t o underst and some of t he mechanisms by w hich t hey do so. How ever, w e not e t hat t erminology such as ‘a gene f or X’ or ‘a set of genes f or X’ is very misleading because it f ails t o convey t he complexit y of t he role of genet ic f act ors in causal explanat ions of human behaviour. Genes det ermine w hich prot eins are made. They do not det ermine w hich behavioural or personalit y t rait s an individual possesses. Furt hermore, t he product of an individual gene w ill only very rarely be direct ly relat ed t o a complex behavioural charact erist ic. It w ill normally int eract w it h many ot her genes and w it h many non-genet ic f act ors, w hich means t hat t he predict ive capabilit y of t est s f or any single or small number of genes w ill in general probably be quit e limit ed. Nonet heless, t he prot eins t hat genes make and t he w ay t hese aff ect our bodies and brains w ill be one part of an explanat ion of human behaviour (paragraph 3.20).

Reporting research in behavioural genetics Research w hich claims t o show an associat ion bet w een part icular genet ic variant s and part icular t rait s t ends t o receive considerable at t ent ion in t he scient if ic and lay media. The various met hods of research in t his f ield are not inf allible, and t he review s of t he evidence in Chapt ers 7–10 show t hat f ew f indings have been replicat ed successf ully t o dat e. Thus, report s of such t hings as ‘gay genes’ or ‘smart mice’ convey a highly inaccurat e impression of t he st at e of t he research. The lack of report ing of negat ive or cont radict ory f indings exacerbat es t his problem. These diff icult ies are not unique t o research in behavioural genet ics. How ever, it does seem t hat such research is, at present , part icularly suscept ible t o report ing w hich, w het her st rict ly accurat e or not , is misleading in t he impression it gives t o t he reader. The pot ent ial f or t he abuse of f indings in t his area means t hat t he report ing of t his research ought t o be conduct ed w it h part icular care. We consider t hat researchers and t hose w ho report research have a dut y t o com m unicat e f indings in a responsible m anner. We w elcom e t he Guidelines on Science and Healt h Communicat ion published by t he Social Issues Research Cent re, t he Royal Societ y and t he Royal Inst it ut ion of Great Brit ain and recom m end t hat f urt her init iat ives in t his area should be encouraged (paragraph 11.14).3 In t he cont ext of research in behavioural genet ics, w e recommend t hat t he f ollow ing point s, concerning t he various t ypes of research, are borne in mind by t hose w ho report on, comment on and evaluat e such research:

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2

Rut t er, M . & Silberg, J. (2002). Gene-environment int erplay in relat ion t o emot ional and behavioural dist urbance. An. Rev. Psychol. 53, 463-490.

3

Social Issues Research Cent re, t he Royal Societ y and t he Royal Inst it ut ion. Guidelines on Science and Healt h Communicat ion. November 2001. ht t p://w w w.sirc.org/publik/revised_guidelines.pdf (9 Aug 2002).

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■ Quant it at ive genet ics involves st at ist ical met hods t hat at t empt t o dist inguish t he eff ect s of genet ic and environment al f act ors on variat ion in cert ain behavioural t rait s, w hich can be quant it at ively measured, bet w een groups of individuals. ■ The subject s of t he research are usually t w ins, siblings, adopt ed children, and f amilies.

M olecular genetics

■ Research in molecular genet ics t ries t o ident if y variat ion in part icular genes t hat inf luences behaviour, by examining t he DNA of individuals.

RECO M M EN D ATI O N S

■ Est imat es of herit abilit y and ot her st at ist ical t echniques are usef ul in underst anding t he relat ive cont ribut ion of dif f erent t ypes of inf luence and t heir relat ion t o each ot her. They are also usef ul f or underst anding w hy some t ypes of behaviour of t en occur t oget her. They do not , how ever, lead direct ly t o predict ive inf ormat ion regarding individuals, nor do t hey give reliable est imat es of how st rongly predict ive a genet ic t est might be if it w ere developed (Box 4.1).

A N D

■ The st at ist ics such as est imat es of herit abilit y generat ed by t he research ref er t o groups of people, not t o individuals. Nor do t hey ref er t o part icular genes or regions of DNA or t o specif ic environment al f act ors. This requires f urt her research and addit ional measurement .

SU M M A RY

Quantitative genetics

■ This is diff icult because t here are usually many genes involved, each of w hich may only have a small eff ect . M any associat ions bet w een a genet ic variant and a behavioural t rait have been report ed but have not been successf ully repeat ed by ot her researchers. ■ In most cases, t he research does not explain how t he gene inf luences t he behaviour. How ever, some researchers predict t hat t hey w ill overcome t hese diff icult ies and t hat genes t hat inf luence behaviour w ill be reliably ident if ied. ■ When associat ions are report ed by researchers, it is import ant t o consider t he f ollow ing quest ions: – How convincing is the evidence, in terms of both statistical analysis and the supposed pathway of causation, that the claim is correct? Much more credibility can be attached to findings that have been independently replicated by a different research group, and first reports of gene–behaviour associations should be treated with caution until they are replicated. – Over w hat range of populat ions and environment al condit ions has t he eff ect been t est ed? – If claims are made about t he pract ical applicat ion of t he f indings t o inf luence human behaviour, w hat is t he size of t he eff ect of t he genet ic variant ? Is it large enough t o have any relevance f or t he t est ing of individuals? – What are t he implicat ions f or t he pat hw ay of causat ion of t he behaviour? (Box 5.1) Research involving animals

■ Animal models have great ly advanced our underst anding of how genes have an eff ect in t he organism and of how t he brain develops. ■ Animal models can be creat ed by various t echniques including select ive breeding and t he direct manipulat ion of specif ic genes. ■ Alt hough t here are many similarit ies w it h regard t o genet ics bet w een human and non-human animals, t here are also considerable diff erences in t he expression of t heir genes bot h w it hin t he organism and over t ime.

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■ It is diff icult t o equat e direct ly t he richness of complex human t rait s such as int elligence, personalit y and sexual orient at ion w it h t he behaviour of animals. This may limit t he pot ent ial value of t he research. ■ For t hese reasons, caut ion should be exert ed w hen hypot hesising t hat genes st udied in research involving animals w ill have t he same eff ect in humans (Box 6.2).

The evidence for genetic influences on human behaviour In Chapt ers 7–10 w e set out some recent f indings in research in behavioural genet ics int o ant isocial behaviour, int elligence, personalit y and sexual orient at ion. As t hese chapt ers demonst rat e, research is at diff erent st ages in diff erent areas. For some t rait s, areas of t he genome have been ident if ied t hat might cont ain genes w hich have an eff ect on behaviour. For most t rait s, t he rout e f rom such genet ic f act ors t o a part icular behaviour is unclear. The bulk of research in behavioural genet ics t o dat e has relied on quant it at ive met hods t o assess t he relat ive cont ribut ions of diff erent t ypes of f act or. How ever, t he use of molecular genet ics is increasing, a t rend w hich is expect ed t o cont inue. In Chapt er 11, w e draw some general conclusions about t he research in all t he areas described and highlight ed some cent ral t hemes t hat emerge. These inf orm our considerat ion of t he et hical, legal, social and policy issues t o w hich t he research gives rise. The cent ral t hemes t hat emerge are: – t he diff icult y of def ining and measuring behavioural t rait s; – t he dangers of t he misint erpret at ion and misapplicat ion of herit abilit y est imat es; – t he lack of replicat ed f indings relat ing t o specif ic genes t hat might inf luence behaviour.

Ethical issues arising from research in behavioural genetics Free w ill and human dignity We conclude t here is no inherent conf lict bet w een a great er underst anding of genet ic cont ribut ions t o behaviour and due regard f or human dignit y. A non-reduct ive, rat ionalist , underst anding of human f reedom can coexist w it h recognit ion of t he genet ic inf luences on our human abilit ies, capacit ies and mot ivat ions, even t hough a reduct ive, f unct ionalist , account f it s more readily alongside t he scient if ic perspect ive employed by behaviour genet icist s. It is not necessary here t o t ake a st and on t his debat e. But any sensible underst anding of human f reedom and dignit y must allow f or some st art ing-point in t he development of t he abilit ies w hich are cent ral t o t his f reedom and dignit y. Behavioural genet ics promises t o elucidat e t his st art ing-point , and t hereby cont ribut e t o t he underst anding of humanit y. But it no more off ers a complet e t heory of human behaviour t han does any ot her single scient if ic discipline. Thus, t here is no reason f or adherent s of behavioural genet ics, or crit ics, t o regard it as off ering a radically new w ay of underst anding human lif e w hich t hreat ens t o undermine t he dignit y of humanit y. It complement s, and does not displace, t he f amiliar social sciences, t he humanit ies and indeed our ordinary underst anding of behaviour (paragraph 12.38).

Will there be any practical applications of research in behavioural genetics? While everyone accept s t hat genes have an impact on behaviour, genet ic t est s w ill have a low predict ive capacit y because of t he myriad ot her f act ors t hat inf luence our behaviour and t he vast ly complex int eract ions bet w een genet ic f act ors t hemselves. Hence, it has been argued t hat it w ill be impossible t o make any robust predict ions based on genet ic t est s, or t o design any eff ect ive int ervent ions as a result of t hem, and t heref ore, t hat t here is no point in discussing t he et hics of t heir applicat ion. We t ake t he view t hat t hese considerat ions do not exempt us f rom xxiv

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As t he review s of t he evidence in chapt ers 7-11 indicat e, f at alism about genet ics is a misconcept ion. Even w hen behavioural t rait s are inf luenced by genes, t here are alw ays ot her inf luences, and t he exist ence of genet ic inf luences does not show t hat w e are pow erless t o change or modif y our charact er. Nonet heless, t his misconcept ion is pervasive and gives rise t o t he anxiet y t hat behavioural genet ics w ill lead t o t he ‘medicalisat ion’ of t hose w ho are f ound t o be genet ically predisposed t o cert ain behavioural t rait s. At t he root of such concerns is t he idea t hat behavioural t rait s t hat have previously been regarded as ‘normal’ w ill come t o be view ed as ‘abnormal’ or pat hological.

RECO M M EN D ATI O N S

Trait s such as sexualit y, aggression and int elligence have in t he past been t hought of as out comes of inherit ance, f amily background, socio-economic environment , individual choice and even divine int ervent ion. If research in behavioural genet ics ident if ies t he inf luence of genes on such t rait s, t hese t rait s may mist akenly come t o be t hought of as being f undament ally det ermined by genet ic f act ors and even as aspect s of lif e w hich belong t o one’s ‘f at e’.

A N D

M edicalisation and other concerns

SU M M A RY

considering anxiet ies aroused by popular belief s in t his area, even if t hese belief s t urn out t o be misconcept ions. For in t he past , social policies, f or example eugenic policies, have been built on minimal or erroneous scient if ic f oundat ions. M ore recent ly misunderst andings about genet ics have led t o unw arrant ed discriminat ion. M oreover, w e consider t hat , in t he f ut ure it may become possible t o make predict ions, albeit limit ed ones, about behaviour based on genet ic inf ormat ion and t o design usef ul applicat ions of t his know ledge. Theref ore, w hile it is cert ainly t oo early t o discuss det ailed applicat ions of behavioural genet ics, w e need t o conf ront anxiet ies based on current belief s about t his subject (paragraphs 13.2-13.6).

M edicalisat ion is an issue t hat aff ect s many areas of lif e, not just behavioural genet ics. In t he case of behavioural t rait s, since research int o genet ic inf luences is at an early st age, it is not possible t o say w het her medicalisat ion w ill be likely, or w het her it w ill have, on balance, posit ive or negat ive implicat ions. How ever, examples of t he delet erious eff ect s of medicalisat ion in ot her areas suggest t he need f or aw areness of pot ent ial problems. We conclude t hat research in behavioural genet ics has t he pot ent ial t o cont ribut e t o t he exist ing phenom enon of m edicalisat ion. Delet erious eff ect s t hat should be borne in m ind include shif t ing t he boundary bet w een norm al variat ion and disorder f urt her aw ay f rom t he ext rem es of variat ion; reducing social t olerance of previously ‘norm al’ behavioural t rait s; and t he rout ine select ion of genet ic or m edical int ervent ions w it hout adequat e considerat ion being given t o environm ent al int ervent ions and ot her opt ions (paragraph 13.23). Any discovery of biological mechanisms t hat inf luence behaviour, including genes, may aid in t he development of drugs w hich modif y behaviour. We consider t hat t here is pot ent ial f or t he unhelpf ul w idening of diagnost ic cat egories, t o encourage t he use of medicat ion by people w ho w ould not necessarily be t hought of as exhibit ing behavioural t rait s out side t he normal range. In addit ion t o t he pot ent ially harmf ul eff ect s already list ed, t his could lead t o unnecessary increased expendit ure by t he healt h service. We recom m end t hat healt h service providers, and in part icular t he Depart m ent of Healt h, specif ically charge a nam ed agency w it h m onit oring and, if necessary, cont rolling, t his m eans of t he deliberat e m edicalising of norm al populat ions (paragraph 13.24). Despit e concerns about medicalisat ion and st igma, w e consider t hat t here is, prima f acie, no reason f or pref erring one t ype of int ervent ion over anot her as a mat t er of principle. For any given t rait and any given individual, t he f act ors inf luencing t he development and expression of

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t hat t rait are likely t o be many and varied. In diff erent cases, t here may be reasons f or t hinking t hat diff erent f orms of int ervent ion are appropriat e. We ident if y f ive f eat ures of any int ervent ion t hat may provide moral reasons f or accept ing or reject ing t heir use, namely t he eff ect iveness, saf et y and reversibilit y of t he int ervent ion, t he ext ent t o w hich one can make choices about it s use, and it s implicat ions f or individualit y (paragraph 13.26).

Gene therapy The Unit ed Nat ions Educat ional, Scient if ic and Cult ural Organizat ion (UNESCO) Universal Declarat ion on t he Human Genome and Human Right s st at es in Art icle 5 t hat ‘Research, t reat ment or diagnosis aff ect ing an individual's genome shall be undert aken only af t er rigorous and prior assessment of t he pot ent ial risks and benef it s pert aining t heret o and in accordance w it h any ot her requirement of nat ional law '.4 The Clot hier Report on t he et hics of gene t herapy ident if ied a number of w ays in w hich gene t herapy might pose a risk t o saf et y.5 These included mist akes in insert ing t he correct ing gene, t he possibilit y t hat t he gene w ould be expressed in t he w rong place or at t he w rong t ime, t he possibilit y t hat insert ion of t he gene might cause a new mut at ion or genet ic disease, and t he possibilit y t hat t he correct ing gene might move f rom it s t arget locat ion in t he body and aff ect ot her cells. As a result , all applicat ions t o carry out t rials of gene t herapy in humans in t he UK are monit ored by t he Gene Therapy Advisory Commit t ee (GTAC). We consider t hat in view of t he risks inherent in gene t herapy, considerable caut ion should be exercised bef ore cont em plat ing it s applicat ion t o t rait s t hat do not have serious im plicat ions f or healt h. We not e t hat if som at ic gene t herapy f or t rait s in t he norm al range w ere t o becom e a possibilit y, any research w ould f all under t he rem it of t he Gene Therapy Advisory Com m it t ee (GTAC).6 We recom m end, t heref ore, t hat t he GTAC and ot her relevant bodies should develop guidelines f or research int o gene t herapy f or norm al behavioural t rait s bef ore such research t akes place (paragraph 13.31). Germline gene t herapy raises part icular issues concerning saf et y because t he eff ect s of t he t herapy reach f ar int o t he f ut ure and cannot be easily predict ed. The Clot hier Report concluded t hat ‘t here is insuff icient know ledge t o evaluat e t he risks [of germline gene t herapy] t o f ut ure generat ions’ and t hat t heref ore ‘gene modif icat ion of t he germ line should not yet be at t empt ed’. In t he cont ext of behavioural variat ion w it hin t he normal range, w hich by def init ion is not lif e-t hreat ening, w e cannot envisage any circumst ances in w hich t he modif icat ion of t he human germline w ould be just if iable (paragraph 13.32).

Access to interventions Therapy versus enhancement

The w ay t o dist inguish bet w een t hose int ervent ions w hich count as ‘t herapies’ and t hose w hich count as ‘enhancement s’ is by ref erence t o t he condit ion t hat is t o be alt ered: t herapies aim t o t reat , cure or prevent diseases and t o alleviat e pat hological condit ions w hich place someone out side t he normal range, w hereas enhancement s aim t o improve already healt hy syst ems and t o advance capacit ies w hich already f all w it hin t he normal range. This dist inct ion is of t en used t o just if y a dist inct ion bet w een int ervent ions w hich merit public support and t hose w hich do not .

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4

Unit ed Nat ions Educat ional, Scient if ic and Cult ural Organisat ion. (November 1997). Universal Declarat ion on t he Human Genome and Human Right s.

5

Commit t ee on t he Et hics of Gene Therapy (Chairman: Clot hier, C.). (1992). Report of t he Commit t ee on t he Et hics of Gene Therapy. London: HM SO; Cm 1788.

6

GTAC’s remit is ‘t he deliberat e int roduct ion of genet ic mat erial int o human somat ic cells f or t herapeut ic, prophylact ic or diagnost ic purposes’. An analogous role is perf ormed in t he US by t he Food and Drug Administ rat ion (FDA). In July 2002, it w as report ed t hat t he FDA is t o creat e a new depart ment t o oversee gene t herapy, w it hin t he Cent er f or Biologics Evaluat ion and Research (New FDA Off ice f or Gene Therapy. (2002). Nat . M ed. 8, 646).

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RECO M M EN D ATI O N S

Providing tests and interventions

A N D

Alt hough t herapy is usually t hought of as t he t reat ment of diseases w it h an ident if iable biochemical basis, t here can be cases in w hich someone suff ers f rom a pat hological condit ion w hich places t hem out side t he normal range in some respect , w it hout t here being any such ident if ied basis f or it . In such cases, int ervent ions t o overcome t he result ing impairment are also t o be regarded as t herapies; hence, such int ervent ions merit public support t o make t hem available t o all. The import ant issue is t he severit y of t he handicap, not it s cause. We t ake t he view t hat t his conclusion should be applied t o int ervent ions w hich become available in t he f ield of behavioural genet ics. Any decision t o provide public support t hrough t he Nat ional Healt h Service (NHS) f or int ervent ions t o enable individuals t o overcome disabilit ies w hich obst ruct t heir capacit y f or behaviour in t he normal range should not be dependent on t he underlying cause of t he disabilit y (paragraphs 13.41-13.43).

SU M M A RY

The suggest ion is t hat t here is a dut y t o ensure t hat our f ellow cit izens receive t herapies, but no dut y t o ensure t hat t hey receive enhancement s. The dist inct ion bet w een t herapy and enhancement is not st raight f orw ard and requires qualif icat ion, but t he principle w hich associat es it w it h t hat bet w een public and privat e provision is a usef ul st art ing-point in t his area.

Who should be able t o make use of genet ic t est s and int ervent ions if t hey are developed? And w ho should bear t he cost of t he t est s and int ervent ions? A st andard view is t hat since t he st at e does not have an obligat ion t o provide t echniques f or improving int elligence or at hlet icism or changing behaviours, t hese int ervent ions should not normally be provided as part of a public healt hcare syst em. Nonet heless, it may also be argued, t hat w it hin a f ree societ y and a f ree market , t hese t echniques should be available f or purchase. The anxiet y, how ever is t hat if such t est s and int ervent ions w ere available f or privat e purchase, t he result could be t hat only t he more aff luent members of societ y w ould have access t o t hem. Because t hese t echniques w ould enhance capabilit ies, t his could lead t o even great er inequalit ies and increase social and economic polarisat ion. Public provision of new t est s and int ervent ions, especially w hen accompanied by f urt her eff ort s t o prevent t he f ormat ion of an underclass, w ould, of course, require considerable resources. From an egalit arian perspect ive, if t hese resources are not available, t hen t he t est s and int ervent ions should not be int roduced at all. How ever, libert arians argue t hat t here is no moral basis f or a dist inct ion bet w een int ervent ions based on genet ic variant s and t he f amiliar use of ext ra resources in t he f ields of educat ion and sport . In part icular, if a t rait is desirable and t here is an int ervent ion t hat w ill increase t he likelihood of it occurring, t he correct response is t o ensure t hat it is available as w idely as possible. While t his may ent ail t hat , f or at least a limit ed period of t ime, t here w ill be some w ho do not have access, t he overall goal should be t o raise everyone t o t he highest level. It is diff icult t o adjudicat e in t he abst ract bet w een t hese egalit arian and libert arian posit ions. It is only once some eff ect ive int ervent ion is under considerat ion t hat t he cost s and benef it s of f ull public availabilit y versus limit ed privat e availabilit y f or a privileged f ew can be assessed seriously. We believe t hat equalit y of opport unit y is a f undam ent al social value w hich is especially dam aged w here a societ y is divided int o groups t hat are likely t o perpet uat e inequalit ies across generat ions. We recom m end, t heref ore, t hat any genet ic int ervent ions t o enhance t rait s in t he norm al range should be evaluat ed w it h t his considerat ion in m ind (paragraph 13.48). M onitoring the provision of genetic tests and interventions

If genetic tests and corresponding genetic, medical or environmental interventions relevant to traits

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in the normal range are developed, it is important to consider how such tests and interventions may be made available. Genetic tests for variants that influence behaviour in the normal range might be thought of as comparable to personality or IQ tests, rather than genetic tests that are used to diagnose or predict the onset of a serious disease such as cancer. Similarly, interventions might be seen as comparable to vitamin supplements or cosmetic surgery. In both cases, therefore, if the comparisons are a guide, it may turn out that individuals are left to make decisions about whether to make use of tests or interventions without the involvement of health professionals. This has import ant implicat ions f or t he regulat ion and monit oring of t est s and int ervent ions. Wit hout appropriat e saf eguards, consumers may be at risk of exploit at ion t hrough misleading market ing pract ices. This is part icularly likely in novel areas of science, w here most people w ill not be w ell placed t o make inf ormed judgement s. In t he case of genet ic t est s, t here is current ly no specif ic legislat ion in place t hat w ould provide a regulat ory mechanism f or assessing t he eff icacy or reliabilit y of a t est . This applies even t o genet ic t est s f or diseases, as w ell as t o t he hypot het ical t est s f or genet ic inf luences on behavioural t rait s t hat are t he f ocus of t his Report . We consider t hat t he issues raised by t est s f or behavioural t rait s and ot her t rait s t hat exhibit normal variat ion, rat her t han t est s f or diseases, require specif ic at t ent ion. The quest ions addressed by t hese t est s include very sensit ive areas of personal and f amily vulnerabilit y, and t here is considerable pot ent ial f or exploit at ion of t he anxiet ies and aspirat ions of members of t he public in an area w here t he science is not w ell underst ood. This danger is part icularly import ant since bot h t est s and int ervent ions might be applied t o children w it hout t heir consent . Thus, w e t ake t he view t hat it is not adequat e in t his area t o rely on t he same mechanisms t hat apply t o non-genet ic or non-medical enhancement s, such as recourse t o t he Advert ising St andard Aut horit y or t he Off ice of Fair Trading, t o prevent misleading claims being made and ineff ect ive t est s f rom being sold. In 1997, t he Advisory Commit t ee on Genet ic Test ing (ACGT), a non-st at ut ory commit t ee t hat report ed t o t he Depart ment of Healt h, produced a Code of Pract ice and Guidance on Human Genet ic Test ing Services Supplied Direct t o t he Public.7 The ACGT w as subsumed in 2001 by t he Human Genet ics Commission (HGC), w hich current ly has responsibilit y f or administ ering t he Code of Pract ice. The HGC issued a public consult at ion document on t he supply of genet ic t est s direct t o t he public in July 2002.8 This summarises t he current sit uat ion and poses a number of specif ic quest ions covering issues such as consent t o t est ing, st orage and use of samples, and conf ident ialit y of dat a. It not es t hat t est s in t he f ield of behavioural genet ics are likely t o be part icularly cont roversial. On t he presum pt ion t hat t est s f or genet ic inf luences on behavioural t rait s in t he norm al range, of varying qualit y and predict ive pow er, w ill becom e available, w e w elcom e t he considerat ion by t he Hum an Genet ics Com m ission (HGC) of genet ic t est s supplied direct ly t o t he public. We encourage t he HGC t o give t horough considerat ion t o t he issues raised by genet ic t est s f or behavioural and personalit y t rait s. We recom m end t hat bot h t he public and privat e provision of such t est s, if t hey are developed, should be st ringent ly m onit ored and regulat ed as necessary (paragraph 13.53).

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7

Advisory Commit t ee on Genet ic Test ing. (Sept ember 1997). Code of Pract ice and Guidance on Human Genet ic Test ing Services Supplied Direct t o t he Public. London: Healt h Depart ment s of t he Unit ed Kingdom.

8

Human Genet ics Commission. (July 2002). Consult at ion on Genet ic Test ing Services supplied Direct t o t he Public. ht t p://w w w.hgc.gov.uk/t est ingconsult at ion/index.ht m (16 Jul 2002).

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A N D RECO M M EN D ATI O N S

In t he case of genet ic int ervent ions t he use of gene t herapy w ill be regulat ed by t he Gene Therapy Advisory Commit t ee (GTAC). M edical int ervent ions such as pharmacological subst ances w ill not necessarily be classif ied as medicines. While some w ould be subject t o t he exist ing regulat ion in place f or medicines, ot hers might be classif ied as f oodst uff s or herbal remedies. Those w hich are not classif ied as medicines are unlikely t o be harmf ul, but t here is a risk t hat t hey w ill be promot ed on t he basis of unreliable, or even non-exist ent scient if ic evidence, and t hat consumers w ill be misled. Similarly, environment al int ervent ions, such as changes in lif est yle or surroundings, may be promot ed on t he basis of genet ic inf ormat ion about an individual. As not ed above, w e do not consider t hat t here are current ly any public bodies const it ut ed in such a w ay as t o monit or t he provision of such int ervent ions eff ect ively and ensure t hat t hey are appropriat e and of suff icient ly high qualit y. We recom m end, t heref ore, t hat t hose charged w it h t he m onit oring and regulat ion of genet ic t est s f or behavioural t rait s in t he norm al range should also be responsible f or ensuring appropriat e m onit oring of t he provision of int ervent ions based on such genet ic inf orm at ion, w hich f all out side t he scope of ot her regulat ory bodies (paragraph 13.55).

SU M M A RY

In addit ion t o genet ic t est s, int ervent ions may be developed, w het her medical, genet ic or environment al, on t he basis of inf ormat ion about genet ic variant s. The HGC consult at ion document recognises t hat some genet ic t est s may be accompanied by a corresponding int ervent ion t hat is recommended, depending on t he t est result s. How should such int ervent ions be regulat ed?

We not e t he diff icult ies f or monit oring and regulat ion raised by t he sale of exist ing t est s and int ervent ions on t he int ernet , and encourage t he eff ort s of t he Off ice of Fair Trading and consumer prot ect ion agencies such as t he Nat ional Consumer Council and t he Consumers’ Associat ion in developing codes of pract ice and st rat egies, such as kit e-marks, f or assist ing consumers.

Prenatal selection There are various w ays in w hich w e can aff ect t he charact erist ics of our children. M ost f undament ally, our children are inf luenced by our choice of mat e. How ever, in recent decades, ot her t echniques have been developed w hich ext end our capacit y in t his area. The f irst is prenat al diagnosis (PND) w hich is in w idespread use in t he UK t o det ect pregnancies aff ect ed by diseases such as Dow n’s syndrome and spina bif ida. M any couples opt f or t erminat ion of pregnancy if abnormalit ies are det ect ed. Secondly, in t he past 15–20 years, t he t echnique of preimplant at ion genet ic diagnosis (PGD) has been developed, w hich enables embryos creat ed by in vit ro f ert ilisat ion (IVF) programmes t o be t est ed f or genet ic disorders bef ore t hey are implant ed. A t hird, largely t heoret ical, approach is t o move select ion f urt her back in t ime, by allow ing choice bet w een diff erent gamet es. Experiment al t echniques now allow sperm t o be sort ed, enabling parent s t o choose t he sex of t heir embryo. This t echnique remains somew hat unreliable: t here are report s of an 8% error rat e f or f emales and 28% in males. It is not clear t hat t his t ype of t echnique w ill ever be applicable t o t rait s ot her t han sex, and it is part icularly diff icult t o envisage it s applicat ions t o t he complex t rait s considered in t his Report . The use of t hese t echniques, part icularly PGD and gamet e select ion, has of t en been ref erred t o in t he press and in popular debat e as a quest ion of ‘designer babies’. ‘Designer baby’ is one of t hose t erms, like ‘Frankenst ein f oods’ and ‘slippery slope’, w hich is cent ral t o public discourse on genet ics, but w hich can be misleading. The select ion of gamet es bef ore f ert ilisat ion, of embryos bef ore implant at ion, or select ive t erminat ion of pregnancy are all examples of t he select ion or choice of alt ernat ive opt ions rat her t han t he manipulat ion or design of babies. The possibilit y of

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t ruly designing a child, by choosing charact erist ics f rom a menu of possibilit ies t o creat e a child, f or example using gene t herapy, is st ill in t he realms of science f ict ion (Box 13.2). The f orms of select ion out lined above are current ly only pract ised on clinical grounds in t he UK. How ever, a t rend t ow ards select ion on ot her grounds can be ident if ied. The recent decision by t he Human Fert ilisat ion and Embryology Aut horit y (HFEA) t o allow t he select ion of embryos t hat are f ree f rom genet ic diseases and t hat can act as donors t o exist ing siblings is an import ant move in t his direct ion. M oreover, recent ly, t he Government has request ed t hat t he HFEA examines t he advances in t echniques of gamet e select ion on t he basis of sex, somet hing w hich is already possible and unregulat ed in t he privat e sect or. The HFEA int ends t o launch a public consult at ion on sex select ion in lat e 2002. Law and clinical pract ice support t he use of genet ic inf ormat ion t o provide inf ormed choice f or prospect ive parent s. But prof essional and public opposit ion has been voiced, f or a variet y of reasons, t o t he use of non-clinical at t ribut es such as t he t rait s considered in t his Report in t est ing and select ion. There seems t o be a consensus in clinical genet ics and in public opinion against use of PGD or PND in order t o select babies on t he basis of non-clinical charact erist ics. In t he case of prenat al diagnosis (PND), w e share t his view . Set t ing aside t he cont est ed issue of t he et hics of abort ion on social grounds, w hich is out side t he scope of t his Report , w e t ake t he view t hat t he use of select ive t erm inat ion f ollow ing PND t o abort a f et us m erely on t he basis of inf orm at ion about behavioural t rait s in t he norm al range is m orally unaccept able (paragraph 13.65). But t he issues raised by t he use of PGD are diff erent . Whereas select ive t erminat ion f ollow ing PND is applied t o a f et us t hat has already implant ed and is developing in t he w omb, PGD is used t o select w hich embryos t o implant . Thus, PGD does not precede t he t erminat ion of a pot ent ial human lif e, but precedes inst ead t he choice as t o w hich embryo, among t hose creat ed by IVF, is t o be given a chance of developing int o a human being. And in t his cont ext , it is not so clear t hat it is morally unaccept able t o make t his choice on t he basis of genet ic inf ormat ion about t he t rait s t hat are t he f ocus of t his Report . Whereas PND w ould be used t o end a lif e, PGD is, in eff ect , used t o choose w hich lif e t o st art . Hence, t he moral prohibit ions w hich apply in t he case of PND, do not apply in t he same w ay in t he use of PGD. Nonet heless, t he pot ent ial use of PGD t o select embryos t hat are more or less likely t o exhibit part icular behavioural t rait s is w idely t hought unaccept able. One line of argument in f avour of t he use of PGD is described in t erms of a ‘right t o procreat ive aut onomy’ w hich w ould include a right t o employ saf e and reliable met hods f or t he select ion of children w it h a genet ic predisposit ion f or enhanced abilit ies w it hin t he normal range.9 How ever, w e ident if y a number of argument s against t he use of PGD f or t rait s in t he normal range. In part icular, w e address t he quest ion of ‘nat ural humilit y’. At present , parent s accept t heir children as t hey f ind t hem in an at t it ude of ‘nat ural humilit y’ t o t he unchosen result s of procreat ion. This at t it ude is an import ant f eat ure of parent al love, t he love t hat parent s ow e t o t heir children as individuals in t heir ow n right ; f or t his is a love t hat does not have t o be earned and is not dependent on a child having charact erist ics t hat t he parent s hoped f or. Parent al love w hich includes t his element of nat ural humilit y is, t heref ore, incompat ible w it h t he w ill t o cont rol. It is not compat ible w it h at t empt s t o int erf ere in t he lif e of a child except w here t he int erf erence is in t he child’s ow n int erest . Equally, it is not compat ible

9

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Dw orkin, R. (1993). Lif e’s Dominion. London: Harper Collins.

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A N D RECO M M EN D ATI O N S

Given t hat w e are dealing here w it h only speculat ive possibilit ies, and since t he likely small eff ect s of individual genes may make accurat e predict ions of f ut ure behaviour very diff icult , it is hard t o evaluat e t he disagreement bet w een t he cont rast ing posit ions. In part icular, it may be t hat t he cont rast bet w een t he aff irmat ion of a right t o procreat ive aut onomy and t he def ence of nat ural humilit y is t oo simple. It might t urn out t hat t here are possibilit ies f or modest applicat ions of PGD in relat ion t o t he t rait s considered in t his Report w hich w ould not seriously undermine t he present relat ionship bet w een parent s and t heir children. While not ent irely persuaded by t his conservat ive line of argum ent , w e do accept t hat , at present , t he case f or perm it t ing prenat al select ion based on t he ident if icat ion of genet ic predisposit ions f or enhanced abilit ies rem ains t o be m ade. We recom m end, t heref ore, t hat t he t echnique of preim plant at ion genet ic diagnosis, w hich is current ly rest rict ed t o serious diseases and disorders, should not be ext ended t o include behavioural t rait s in t he norm al range such as int elligence, sexual orient at ion and personalit y t rait s (paragraph 13.78).

SU M M A RY

w it h t he pract ice of prenat al select ion w hich seeks t o ident if y, as a basis f or choice, genet ic predisposit ions f or enhanced abilit ies or special charact er t rait s. For t his is an at t empt t o det ermine t he kind of child one w ill have – w hich is precisely not t he uncondit ional, loving accept ance of w hat ever child one t urns out t o have.

Legal issues: criminal responsibility Attributing responsibility We conclude t hat research in behavioural genet ics does not pose a f undam ent al challenge t o our not ions of responsibilit y as t hey are applied in t he legal cont ext . We consider t hat genet ic variant s in t he norm al range are unlikely t o be considered an excuse f or legal purposes, at least f or t he f oreseeable f ut ure. They f all out side t he scope of t he def ences of insanit y and dim inished responsibilit y and cannot be said t o absolve individuals f rom responsibilit y f or t heir act ions (paragraph 14.24). If progress in behavioural genet ics w ere t o be such t hat close and clearly ident if iable associat ions bet w een part icular genet ic variant s and part icular f orms of ant isocial act s w ere t o be demonst rat ed, t here w ould be a case f or a re-examinat ion of t he legal implicat ions. It might be t hat t he concept of diminished responsibilit y, f or example, could be expanded t o embrace such condit ions, perhaps by redef ining view s of illness. If t his possibilit y w ere t o be considered, t hought w ould have t o be given t o t he pot ent ial dangers of unw arrant ed over-reliance on genet ic inf ormat ion and t he consequences of reducing responsibilit y f or our act ions (paragraph 14.25).

Sentencing We conclude t hat , w it h regard t o t he sent encing of convict ed off enders, t he crim inal law should be recept ive t o w hat ever valid psychiat ric and behavioural evidence is available. The t aking int o account of genet ic f act ors w ould depend on t he degree t o w hich such evidence is convincing and relevant . Credible evidence of inf luence and a robust t est f or t he genet ic f act or in quest ion w ould be essent ial: t he w eight t o be accorded t o such inf orm at ion w ould be det erm ined by t he judge (paragraph 14.32). Current ly, environment al, social and psychiat ric assessment s may be t aken int o account by judges in det ermining appropriat e sent ences. These must also be support ed by valid, accurat e and reliable evidence. It w ould be unw ise t o assume t hat genet ics w ill not be able t o assist in det ermining degrees of blame, even if t he ‘all-or-not hing’ quest ion of responsibilit y is not aff ect ed by genet ic f act ors t hemselves. Such a role w ould not compromise basic assumpt ions as t o responsibilit y. Exchanges bet w een genet ics and t he criminal law are at present not very product ive given t he uncert ain nat ure of t he evidence. This is likely t o change. We recom m end t hat t he crim inal xxxi

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just ice syst em should be open t o new insight s f rom disciplines t hat it has not necessarily considered in t he past . The regular exchange of ideas in t his area bet w een researchers in behavioural genet ics, crim inologist s and law yers could be an eff ect ive m eans of ensuring t hat legal concept s of responsibilit y are assessed against current evidence f rom t he behavioural and m edical sciences (paragraph 14.33).

Predictive use of genetic information We t ake t he view t hat w hile t he reduct ion of ant isocial behaviour and crime are import ant goals, any at t empt t o predict t he behaviour of an individual w ho has not exhibit ed ant isocial behaviour, and t o int ervene accordingly, poses a signif icant t hreat t o civil libert ies and should be t reat ed w it h great caut ion. The use of predict ive genet ic t est s t o ant icipat e ant isocial behaviour f or t he purposes of prevent ive act ion in t he case of individuals w ho have not already exhibit ed such behaviour raises et hical quest ions about balancing t he int erest s of individuals against t hose of societ y. We consider t hat t he predict ive use of genet ic inf orm at ion about behaviour in t he norm al range, used in isolat ion in t he case of individuals w ho have not exhibit ed ant isocial behaviour, is unlikely t o be w arrant ed because of t he predict ive pow er of such inf orm at ion is likely t o be w eak and t here is a risk of f alse predict ions. How ever, w e t ake t he view t hat t he use of such inf orm at ion in conjunct ion w it h inf orm at ion about ot her, non-genet ic inf luences on behaviour m ay be just if ied if t he aim is t o benef it t he individual, and in doing so, t o benef it societ y also. We recom m end t hat t he predict ion of behaviour w it h a view t o det aining an individual w ho has not com m it t ed a crim e is not just if ied, w het her such predict ions are based on inf orm at ion about genet ic or non-genet ic inf luences on behaviour (paragraph 14.44).

Policy issues: employment, education and insurance Employment Various bodies have made recommendat ions concerning t he occupat ional healt h and saf et y of employees and jobseekers in t he cont ext of genet ics. These have t ended t o apply a model of t he aut onomy of t he individual pat ient in t he medical sphere t o t he employment relat ionship. In t he case of behavioural t rait s w it hin t he normal range, w hich are t he subject of t his Report , w e are not concerned w it h pat ient s. M oreover, t he employment relat ionship is less recept ive t o t he applicat ion of t he medical model. The inherent inequalit y of bargaining posit ion and pow er bet w een t he employer and t he individual employee means t hat t he employer is likely t o init iat e t he t est s and t o decide how t hey are t o be administ ered and used. A ‘right t o ref use’ t o t ake a t est t o disclose genet ic inf ormat ion or a ‘right t o know ’ t he out come, is likely t o be of lit t le pract ical value w here t he employee has t o choose bet w een exercising t he right or w aiving it in order t o secure a livelihood. The public int erest or pat ernalist ic just if icat ions f or overriding t he individual’s w ishes w here t here is a serious danger t o t he healt h or saf et y of t he employee or t hird part ies do not exist in t he case of non-clinical behavioural t rait s (paragraph 15.20). This leads us t o make t he f ollow ing conclusions and recommendat ions in t he cont ext of t he use by employers of genet ic t est ing f or behavioural t rait s: ■ The prim ary dut y of em ployers is t o provide a saf e environm ent f or t heir em ployees and ot hers. The aim should be t o rem ove hazards f rom t he w orkplace, not t o rem ove em ployees on t he basis of inherit ed charact erist ics or suscept ibilit y t o part icular f orm s of behaviour w it hin t he norm al range. ■ Em ployees should be select ed and prom ot ed on t he basis of t heir abilit y t o m eet t he requirem ent s of t he job, and t hey should be m onit ored t o ensure t hat t heir perf orm ance m eet s t hose requirem ent s.

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We not e, w it h some concern, t hat t he implicat ions f or educat ion of research in behavioural genet ics have not yet received signif icant crit ical at t ent ion. In t he light of t he issues t hat m ay arise if genet ic inf orm at ion about behavioural t rait s is applied in t he cont ext of educat ion, w e recom m end t hat f urt her invest igat ion of t he w ays in w hich such research m ight be applied, and t he result ing et hical and social issues, be undert aken. We recom m end t hat dialogue bet w een t hose involved in educat ion and researchers in behavioural genet ics be prom ot ed. We recom m end, f urt her, t hat unt il such dialogue and research is undert aken, genet ic inf orm at ion about behavioural t rait s in t he norm al range should not be used in t he cont ext of t he provision of educat ion (paragraph 15.26).

RECO M M EN D ATI O N S

Education

A N D

■ Any inquiry int o t he pot ent ial use of genet ic t est ing of behavioural t rait s in t he w orkplace should include an invest igat ion of t he use of ot her purport edly predict ive scient if ic m et hods, such as psychom et ric t est s, f or sim ilar purposes (paragraph 15.21).

SU M M A RY

■ Em ployers should not dem and t hat an individual t ake a genet ic t est f or a behavioural t rait as a condit ion of em ploym ent . The proper approach w ould be t o m onit or em ployees f or early w arning signs of behaviour (such as violence) t hat w ould m ake t hem incapable of perf orm ing t he job sat isf act orily.

Insurance We recom m end t hat t he use of genet ic inf orm at ion about behavioural t rait s in t he norm al range should be int erpret ed as f alling under t he scope of t he f ive-year m orat orium agreed in t he UK in 2001, and should t heref ore not be used by insurance com panies in set t ing prem ium s. Fut ure discussion of possible legislat ion should include specif ic considerat ion of genet ic inf orm at ion regarding behavioural t rait s. If t he use of such inf orm at ion w ere considered, a t horough exam inat ion of t he accuracy and reliabilit y of any genet ic t est s and t heir likely predict ive pow er w ould be essent ial (paragraph 15.37).

Funding research in behavioural genetics It has proved diff icult t o gauge t he precise ext ent of UK f unding in t his area. Our public consult at ion show ed t hat many people consider t hat , compared t o research on disease, research int o genet ic inf luences on behavioural t rait s in t he normal range ought t o receive low priorit y f or f unding. This w as part ly due t o doubt s about t he likely success of t he research, and part ly due t o concerns about t he pot ent ial applicat ions. We t ake t he view t hat research in behavioural genet ics has t he pot ent ial t o advance our underst anding of hum an behaviour and t hat t he research can t heref ore be just if ied. How ever, w e not e t hat it is im port ant t hat t hose w ho f und research in t his area should cont inue t o f und research of a high calibre, should be t ransparent about t heir f unding pract ices and should be aw are of t he pot ent ial f or t he abuse and m isint erpret at ion of result s. In addit ion, w e recom m end t hat research sponsors w ho int end t o f ocus st rat egic f unding in t his area should pay caref ul at t ent ion t o public concerns about t he research and it s applicat ions (paragraph 11.17).

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Section Int roduct ion and cont ext

1

Chapter Int roduct ion

1

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Why this Working Party is important

1.2

This is a complicat ed area of research in genet ics, of t en cont roversial, occasionally explosive and w it h t he capacit y t o ignit e dangerous passions. There are concerns about t he validit y of some of t he scient if ic met hodologies involved. It is diff icult t o ident if y and int erpret t he inf luence of genet ic f act ors, and it can be just as hard t o def ine and measure t he behavioural t rait s t hemselves. There is no evidence t hat research in behavioural genet ics can expect t o uncover simple correlat ions bet w een one gene and one behavioural t rait . Rat her, complex int eract ions bet w een a number of genes may be involved in an individual’s suscept ibilit y t o possessing a part icular t rait . There w ill also be environment al inf luences on behaviour and genes, and genet ic inf luences on bot h t he environment s w e seek out and t he act ivit y of ot her genes. M oreover, t he eff ect s of our genes change over t ime as w e develop – t hey do not have a cont inuous and unchanging inf luence on our brains and bodies. A f urt her complicat ion is t hat one gene, or group of genes, is likely t o aff ect more t han one t rait . For example, in 1999, researchers in t he US produced a st rain of mice t hat had been genet ically modif ied and t hat appeared t o have an improved memory.2 But in 2001, anot her group of researchers discovered t hat mice w hose genes had been alt ered in t his w ay also had t he capacit y t o suff er more f rom long-t erm pain.3

1.3

A usef ul analogy t hat has been used t o convey t his complexit y is t hat of an orchest ra playing a diff icult score, w hereby a part icular group of genes (or t he not es of t he music) can generat e a large number of diff erent out comes (or int erpret at ions of t he music).4 This complexit y means t hat , even if some genes are f ound t o be associat ed w it h cert ain t ypes of behaviour, t he cont ribut ion t hey each make may be very small, and t he precise eff ect t hey have on any part icular person may be ext remely diff icult t o predict . This w eak cont ribut ion of individual genes, or groups of genes, t o overall suscept ibilit y, is compounded by t he subt le int eract ion of genes amongst t hemselves and w it h t he environment , and t he relat ive unpredict abilit y of human development . If , not w it hst anding all t hese diff icult ies, genes t hat inf luence part icular behavioural t rait s are ident if ied, it could become possible t o t est

1

I N TRO D U CTI O N

Human behaviour is inf luenced bot h by t he genes t hat w e inherit and t he environment in w hich w e live. Wit h t he signif icant advances in our know ledge of genet ics and publicat ion of t he draf t sequence of t he human genome, t he f ocus of research has moved once again t ow ards underst anding t he biological cont ribut ion t o behaviour.1 Some researchers are at t empt ing t o locat e specif ic genes, or groups of genes, associat ed w it h behavioural t rait s and t o underst and t he complex relat ionship bet w een genes and t he environment . This is called research in behavioural genet ics. In cont rast t o research int o t he genet ic basis of diseases and disorders, researchers in behavioural genet ics invest igat e aspect s of our personalit ies such as int elligence, sexual orient at ion, suscept ibilit y t o aggression and ot her ant isocial conduct , and t endencies t ow ards ext raversion and novelt y-seeking.

1

1.1

CH A PTER

Int roduct ion

See f or example Dust er, T. (1990). Backdoor t o Eugenics. New York: Rout ledge. This account report s a subst ant ial rise, during t he 1980s, in t he publicat ion of scient if ic art icles t hat at t empt t o explain t he genet ic basis of behavioural t rait s.

2

Tang, Y. P. et al. (1999). Genet ic enhancement of learning and memory in mice. Nat ure 401, 63–9.

3

Wei, F. et al. (2001). Genet ic enhancement of inf lammat ory pain by f orebrain NR2B overexpression. Nat . Neurosci. 4, 164–9. This eff ect is called pleiot ropy.

4

Schmikle, S. (2002). Int elligence genes prove hard t o map. M inneapolis-St Paul St ar Tribune 18 February. Report ing Prof essor Jonat han Beckw it h (Harvard Universit y).

5

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

f or t he presence of variat ions in t hese genes in individual people. No such t est s current ly exist . M oreover, t here is disagreement about w het her t est s t hat predict human behaviour accurat ely could ever be developed. 1.4

Even if genet ic t est s could not yield predict ions of a def init e out come, it may nonet heless be possible t hat t est s t hat suggest an individual w ill have an increased chance of possessing a part icular t rait t o a great er or lesser degree might be developed. Such hypot het ical t est s might be undert aken f or a variet y of purposes. One purpose w ould be simply t o gain more know ledge about t he inf luence of genes on behaviour. For example, st udying t rait s w it hin t he normal range of behaviour, such as anxiet y, might help in t he search f or t reat ment s f or disorders, such as clinical depression. Anot her purpose might be t hat of int ervent ion or t reat ment , f or example t o prevent aggressive behaviour by using medicines, or by at t empt s t o change relevant aspect s of t he environment . A f urt her purpose might be t hat of select ion. This encompasses, f or inst ance, prenat al t est ing, t he st reaming of children in schools on t he basis of int elligence and apt it ude, t he screening of employees and jobseekers t o exclude t hose w it h t rait s t hat employers consider undesirable, and t he use by insurers of genet ic inf ormat ion about behaviour and personalit y t rait s in order t o est imat e risk. Yet anot her purpose might be t o claim diminished legal responsibilit y f or one’s act ions or t o mit igat e punishment f or criminal behaviour.

1.5

These possibilit ies raise import ant et hical, legal and pract ical issues. If genet ic t est s f or behaviour in t he normal range are developed, parent s w ho w ant children w it h cert ain t rait s might be encouraged t o select part icular embryos or f et uses, or t o seek t o enhance t he t rait s of t heir exist ing children using genet ic manipulat ion. Those w it h t he most desirable genet ic endow ment s could be st reamed int o t he best schools, universit ies, jobs, w hile t hose w it hout t he benef it of enhancement w ould be relegat ed t o a pool of t he less educat ed and less skilled. Alt hough t his may be t he st uff of science f ict ion,5 t here can be no doubt t hat t he idea t hat qualit ies of t he human race could be improved by select ive breeding w as t o some ext ent t aken as just if icat ion f or act s of genocide by t he regime in Nazi Germany. This idea also encouraged t he compulsory st erilisat ion of ment ally handicapped people in Europe and Nort h America. While modern behavioural genet ics is not in any sense driven by eugenic policies, t here is a need t o underst and w hy past ideas and pract ices w ere unaccept able and t o be aw are of t he pot ent ial dangers of genet ic discriminat ion in our open societ y, w here decisions t end t o be made by individuals and based on f reedom of choice. Ot her import ant issues include t he prot ect ion of t he privacy and conf ident ialit y of personal genet ic inf ormat ion, and t he role of educat ion and t he media in inf luencing mist aken belief s about t he f act ors t hat aff ect part icular behavioural t rait s and t he st igmat isat ion of individuals w ho display such t rait s.

1.6

In view of considerat ions such as t hese, t he Nuff ield Council on Bioet hics agreed t hat it w as import ant t o ant icipat e t he et hical, legal and social implicat ions raised by research in behavioural genet ics. The scope of t he Council’s 1993 Report on Genet ic Screening: The Et hical Issues, w as limit ed t o serious diseases. In f ocusing on t he major psychiat ric disorders, t he scope of t he 1998 Report on M ent al Disorders and Genet ics: The Et hical Cont ext w as similarly rest rict ed. The w ork of t he Human Genet ics Advisory Council (HGAC) in t he UK,

5

6

An ext reme f orm of such a societ y is imagined in t he f ilm Gat t aca (1997) w here t he “ InValids” w ho have not been genet ically engineered are condemned t o t he low er ranks of societ y. While t he societ y envisaged in Gat t aca is based on parent al choice, Aldous Huxley’s Brave New World (1932) present s a vision of an aut horit arian societ y in w hich t he st at e is responsible f or producing and condit ioning t he requisit e supply of int elligent and less int elligent individuals.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

The subject of t his Report is human behaviour w it hin t he normal range, as opposed t o t rait s t hat are def ined as illnesses or diseases. An import ant preliminary quest ion is w het her it is act ually f easible t o t alk about a ‘normal range’ of behavioural t rait s. According t o one view, t here is no such st at e as ‘normalit y’, and nor is t here a ‘normal genome’, as each individual is subject t o diff erent genet ic and environment al inf luences.

1.8

There is a danger t hat , in speaking of t he ‘normal’ range, t his Report may be misunderst ood as st igmat ising cert ain kinds of behaviour, namely t hose t hat are at t he ext remes of variat ion. It t heref ore needs t o be emphasised t hat w hen w e use t he phrases ‘normal variat ion’ or ‘behaviour in t he normal range’, no moral evaluat ion or judgement is implied. In t hese phrases, ‘normal’ has a st at ist ical meaning – it ref ers t o t he range of variat ion, usually t hat w hich includes about 95% of t he populat ion, and w hich is t hought not t o cont ain any individuals w it h clinical disorders or diseases. There are ot her approaches t o def ining normal behaviour. They include t he t heory t hat abnormal behaviour is t hat w hich result s in impaired f unct ion in societ y f or t he individual, eit her f rom t he individual’s ow n perspect ive, or f rom an object ive st andpoint , regardless of w het her t he behaviour is st at ist ically rare or not .

1.9

We t ake t he st at ist ical approach merely as our st art ing point , using it t o limit t he f ield of inquiry. We have f ocused on t rait s, such as int elligence, t hat are cont inuously dist ribut ed measures, displayed by each individual in t he populat ion t o a great er or lesser ext ent , and w hich are not commonly view ed as disorders. In Chapt er 13, w e consider f urt her t he quest ion of def ining normal behaviour w it h ref erence t o issues such as medicalisat ion and t he dist inct ion bet w een t herapy and enhancement . For now, w e observe t hat not only are t he boundaries bet w een disorders and variat ion in t he normal range diff icult t o draw, but also t hat t hey can be disput ed at any t ime and can alt er as societ y changes. Homosexualit y has, at t imes, been regarded as a disorder, but t oday is usually regarded as a variat ion w it hin t he normal range of sexual pref erences. We also not e t he f urt her quest ion, w het her pat t erns of behaviour can properly be seen as lying on a cont inuum, w it h disorders as ext remes of normal variat ion, or w het her disorders are qualit at ively diff erent f rom behaviour in t he normal range. For example, is depression an ext reme manif est at ion of neurot icism, a t rait w hich is present in everyone t o some degree, or is it a dist inct disorder? At present , it is not know n w het her t here w ill prove t o be any evidence f rom research in genet ics f or making a qualit at ive dist inct ion bet w een normal and abnormal behaviour, or f or view ing behaviour as lying on a cont inuous spect rum. This is one reason w hy researchers in behavioural genet ics and ot her disciplines consider it import ant t o examine t he genes of people considered t o be w it hin t he normal range as w ell as t hose w ho display ext remes of behaviour.

I N TRO D U CTI O N

1.7

1

Defining the normal range of behavioural characteristics

CH A PTER

and t he Human Genet ics Commission (HGC) w hich replaced it , has also f ocused on inherit ed disease and suscept ibilit y t o clinical disorders. This Report is int ended t o f ill t hat gap and t o draw at t ent ion t o t he implicat ions of research in genet ics w hich f alls out side t he medical sphere. The object ives of t he Working Part y est ablished by t he Council w ere t o def ine and consider t he et hical, legal and social issues arising f rom t he st udy of t he genet ics of variat ion w it hin t he normal range of behaviour charact erist ics. In order t o provide a f act ual and cont ext ual background t o t he issues, t his Report f irst set s out t he hist orical and scient if ic background and examines t he evidence f or t he relat ive import ance of genet ic inf luences on select ed behavioural t rait s. It t hen considers t he pot ent ial applicat ions of t his research and t he et hical, legal and social implicat ions.

7

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

The scope of research in behavioural genetics 1.10 We f ocus on f our areas of research in behavioural genet ics: research int o int elligence, personalit y t rait s, ant isocial behaviour and sexual orient at ion. These w ere select ed t o illust rat e t he range of t opics t hat are being invest igat ed, and because of t he import ant issues t hey raise. ■ Int elligence is a complex phenomenon and t here is considerable debat e about w het her it can be measured eff ect ively. There is subst ant ial disagreement regarding t he ext ent t o w hich genet ic and environment al f act ors inf luence int elligence. ■ Personalit y t rait s have been st udied by psychologist s f or many years. Five core t rait s have been t he f ocus of research in bot h psychology and behavioural genet ics: neurot icism, int roversion/ext raversion, openness, agreeableness and conscient iousness. ■ Ant isocial behaviour is classif ied diff erent ly by ment al healt h clinicians, criminologist s and psychologist s, but a common f act or is t hat it is behaviour w hich violat es t he right s and saf et y of ot hers. It includes t rait s such as aggression and violent behaviour. ■ Sexual orient at ion is regarded by some as a mat t er of choice and by ot hers as a mat t er of biology. What role, if any, do genet ic f act ors play in sexual orient at ion? The answ er t o t his quest ion is bound t o inf luence t he w ay in w hich people react t o homosexualit y. 1.11 We acknow ledge t hat t erms such as ‘ant isocial behaviour’ and ‘ext raversion’ arise f rom part icular disciplines, f or example psychology, and t hat t here is of t en disput e about w hat t hey ref er t o. How ever, since cert ain behavioural t rait s, t hus def ined and labelled, are t he f ocus of research int o behavioural genet ics, w e use t hese t erms. In discussing t hese charact erist ics w e have f ound it usef ul t o compare t hem t o cert ain ot her quant it at ively varying human charact erist ics, such as height , w hich are more amenable t o def init ion and measurement t han behavioural t rait s.

The structure of the Report 1.12 The f irst t w o part s of t he Report explain t he hist orical and scient if ic background t o research in t he f ield of behavioural genet ics. Chapt er 2 out lines t he hist ory of t he eugenics movement and it s prof ound ef f ect on t he development of clinical genet ics and development al psychology since t he Second World War. There is a brief account of evolut ionary psychology as a react ion t o t he behaviourism of t he 1950s and 1960s.6 Chapt er 3 at t empt s t o explain w hat is meant by t he suggest ion t hat genes inf luence or aff ect human behaviour. It does so by examining w hat genes are and how t hey w ork, w hat is meant by genet ic variat ion, w hat w e mean by human behaviour w it hin t he normal range, and how genes might inf luence such behaviour. There are diff erent w ays in w hich one can st udy t he cont ribut ion t hat genet ic f act ors make t o human behaviour. Chapt er 4 examines one of t hese approaches, namely quant it at ive genet ics. This f ield of research aims t o det ermine t he ext ent t o w hich variat ion in a t rait is genet ically inf luenced in a populat ion. It uses st at ist ical met hods t o examine and compare groups of people w it hout f ocusing on

6

8

The Report has been conf ined t o behavioural genet ics. Evolut ionary psychology, w hich at t empt s t o provide explanat ions f or similarit ies in human behaviour rat her t han variat ion bet w een individuals, raises diff erent scient if ic and et hical issues and is not discussed in t he Report .

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

CH A PTER

1.13 The t hird part of t he Report , Chapt ers 7–11, cont ains review s of t he f indings t hat have been obt ained t o dat e in each of t hese met hods of research, w it h respect t o t he behavioural t rait s already list ed: int elligence, personalit y, ant isocial behaviour and sexual orient at ion. The principal t hemes t hat emerge f rom t he review s of t he evidence are summarised in Chapt er 11. The Report has been w rit t en so t hat readers not w ishing t o digest t he scient if ic inf ormat ion cont ained in t he review s of t he evidence can ref er t o t his summary chapt er inst ead, w it hout compromising t heir underst anding of t he overall Report .

1

1.14 The f ourt h part of t he Report examines t he et hical, legal and policy issues and off ers a series of conclusions and recommendat ions. A st art ing point is t he recent Unit ed Nat ions Educat ional, Scient if ic and Cult ural Organizat ion (UNESCO) Universal Declarat ion on t he Human Genome and Human Right s w hich st at es t hat t he ‘human genome underlies t he f undament al unit y of all members of t he human f amily, as w ell as t he recognit ion of t heir inherent dignit y and diversit y’.7 Chapt er 12 begins by discussing w het her t here is an inherent conf lict bet w een underst anding t he genet ic inf luences on behaviour and human dignit y, as it is expressed in t he concept s of f ree w ill and moral responsibilit y. Chapt er 13 t hen addresses some of t he pot ent ial applicat ions of t he research including genet ic, medical and environment al int ervent ions aimed at changing behavioural t rait s, as w ell as prenat al select ion. Chapt er 14 is concerned w it h t he implicat ions of research in behavioural genet ics f or t he criminal just ice syst em, in relat ion t o at t ribut ions of legal responsibilit y and sent encing, and in predict ing ant isocial behaviour. Chapt er 15 considers genet ic t est ing and select ion w it h regard t o educat ion, employment and insurance.

7

I N TRO D U CTI O N

part icular genes. Chapt er 5 explains anot her approach, t hat of molecular genet ics. This at t empt s t o ident if y diff erences in part icular genes t hat cont ribut e t o variat ion bet w een part icular individuals. A t hird approach is t he use of animals t o t ry t o examine t he eff ect s of part icular genes on behaviour. Chapt er 6 examines t his t ype of research.

Unit ed Nat ions Educat ional, Scient if ic and Cult ural Organisat ion. (November 1997). Universal Declarat ion on t he Human Genome and Human Right s.

9

Chapter The hist orical cont ext

2

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2.1

TH E H I STO RI CA L CO N TEX T

Box 2.1: Concerns about eugenics expressed by

2

The lit eral meaning of t he t erm eugenics is ‘w ell born’. It ref ers t o t he doct rine t hat humanit y can be improved by select ive breeding, t hat is, by encouraging t hose w it h desirable t rait s t o reproduce or discouraging t hose w it h undesirable t rait s f rom doing so. The eugenic movement is relevant t o t he present considerat ions of genet ics and behaviour because int ellect ual abilit ies and behaviour of various kinds w ere cent ral t o most eugenic policies and pract ices, and t he st udy of behavioural genet ics w as est ablished by scient ist s w orking w it hin t he cont ext of t he eugenics movement . This hist ory remains part of w hat underlies many of t he anxiet ies expressed t oday among prof essionals and members of t he public t ow ards w ork on genet ics and int ellect ual abilit ies and ot her behavioural t rait s. Current w ork in behavioural genet ics has been described as ‘t he second of t w o eras in w hich t he science of heredit y has promised t o off er great benef it s f or mankind’, making it ‘inevit able t hat t oday’s genet ics proceeds in t he shadow of eugenics.’ 1 M any of t he respondent s t o t he Working Part y’s public consult at ion made links of various kinds bet w een research in behavioural genet ics and eugenics (see Box 2.1).2

CH A PTER

The hist orical cont ext

respondents to the public consultation ‘

‘The not ion t hat behavioural t rait s are passed f rom one generat ion t o anot her, “ in t he blood” , has been common currency f or a very long t ime. It has been used t o just if y racism, persecut ion and genocide, it has been used t o st ereot ype individuals, and it has been used t o proclaim t he superiorit y of an individual or group over ot hers.’ Brit ish Psychological Societ y

‘

‘Public healt h policy in t he cont ext of genet ics is f requent ly described as eugenic … behavioural genet ics w ill, on balance, be cont rary t o t he public int erest , precisely because it may lead t o reduced accept ance and respect f or diversit y and people w it h handicap.’ Public Healt h Genet ics Net w ork ‘t here is a possible scenario of a genet ic mast er race being creat ed, somet hing bet w een Hit ler and Brave New World w it h unpredict able consequences. Even if t he t echniques are new, t he lessons of t he Third Reich should not be f orgot t en.’ M r Chris Barchard ‘The research w ould seem t o be unnecessary since it is concerned w it h normal people. The main just if icat ion of t his research w ould seem t o be some f orm of eugenics w hich is morally repugnant t o most people and so t he research should not t ake place.’ M rs Gaynor M it chell ‘int elligence, aggression, ant isocial behaviour … The very choice of t his list links modern behavioural genet ics t o it s eugenic past , as t hese w ere exact ly t he issues t hat concerned t he early t w ent iet h cent ury eugenicist s.’ Prof essor St even Rose

1

Buchanan, A., Brock, D., Daniels, N. & Wikler, D. (2000). From Chance t o Choice: Genet ics and Just ice. Cambridge: Cambridge Universit y Press.

2

Nuff ield Council on Bioet hics. (19 M arch 2001). Genet ics and human behaviour: t he et hical cont ext . Public consult at ion document . ht t p://w w w.nuff ieldbioet hics.org/f ilelibrary/doc/consult at ion_document _f inal.doc (13 Aug 2002).

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

2.2

While select ive breeding in plant s and animals is as old as agricult ure, it became increasingly eff ect ive in t he ninet eent h cent ury. This populat ed f arms in West ern Europe, and ‘Neoeurope’ (t emperat e Nort h and Sout h America and Aust ralasia) w it h improved breeds and st rains w hich came t o dominat e t he w orld f ood t rade, as t hey st ill do t oday. The success of t he select ive breeding of plant s and animals is evidence t hat bot h physical and behavioural charact erist ics can be changed over generat ions by select ion so t hat t he relevant charact erist ics are, at least t o some degree, inherit ed. Not surprisingly, in a climat e in w hich t he breeding of animals w as much discussed and visibly eff ect ive, debat es also included t he possibilit y of t he select ive breeding of humans, and, consequent ly, t he improvement of t he gene pool. This lat t er is w hat Francis Galt on, in 1883, t ermed eugenics. His cousin, Charles Darw in, put t he argument clearly: ‘Wit h savages, t he w eak in body or mind are soon eliminat ed, and t hose t hat survive commonly exhibit a vigorous st at e of healt h. We civilised men, on t he ot her hand, do our ut most t o check t he process of eliminat ion, w e build asylums f or t he imbecile, t he maimed and sick, w e inst it ut e poor-law s; and our medical men exert t heir ut most skill t o save t he lif e of everyone t o t he last moment . There is reason t o believe t hat vaccinat ion has preserved t hose w ho f rom a w eak const it ut ion w ould have f ormerly succumbed t o smallpox. No-one w ho has at t ended t o t he breeding of domest ic animals w ill doubt t hat t his must be highly injurious t o t he race of man. It is surprising how soon a w ant of care, or care w rongly direct ed, leads t o t he degenerat ion of a domest ic race; but except ing in t he case of man himself , hardly anyone is so ignorant as t o allow his w orst animals t o breed’.3

1 4

2.3

The f irst recorded experiment in t he select ive breeding of humans t ook place in John Humphrey Noyes’ Perf ect ionist Communit y at Oneida in New York St at e.4 Bet w een 1869 and 1879 f if t y-eight ‘st irpicult s’ 5 w ere born t o members of t he Communit y select ed on grounds of int elligence, physique and ot her charact erist ics. The children w ere caref ully st udied and judged t o be superior in t heir physique and int ellect .6 How ever, w het her t his can be at t ribut ed t o t he Communit y’s at t ent ion t o ‘t he law s of breeding’, or it s mat erial prosperit y, educat ion and social policies, is anot her mat t er.

2.4

By t he early decades of t he t w ent iet h cent ury, eugenic policies and pract ices w ere in place in almost all indust rialised count ries, and some version of eugenic t hought w as common ground across t he polit ical spect rum. Policies and pract ices varied w idely f rom count ry t o count ry. M ost included posit ive eugenics, designed t o increase f ert ilit y among t hose deemed t o be f it , and negat ive eugenics, designed t o reduce or prevent reproduct ion by t hose held t o be unf it . In Brit ain t he demographic t ransit ion, w it h f alling birt h rat es especially among t he middle and upper classes, provided a st rong incent ive f or eugenic policies w hich included t he incarcerat ion of t he ‘f eeble minded’ and ‘morally incompet ent ’ t o segregat e t hem, as w ell as at t empt s t o increase t he birt h rat e of t he middle classes. Follow ing a Royal Commission on t he Causes and Cont rol of t he Feeble M inded, t he 1914 M ent al Def iciency Act allow ed t he compulsory det ent ion of individuals in st at e inst it ut ions t o cont rol f ert ilit y. The First World War w as generally regarded as a eugenic disast er

3

Darw in, C. (1871). The Descent of M an, and Select ion in Relat ion t o Sex. 2nd ed. London: John M urray. pp. 133–4.

4

Carden, M . L. (1998). Oneida: Ut opian Communit y t o M odern Corporat ion. Syracuse: Syracuse Universit y Press.

5

St irpicult ure is def ined as t he product ion of pure races or st ocks by caref ul breeding.

6

M cGee, A. N. (1891). An experiment in human st irpicult ure. Am. Ant hropol. 4, 319–29.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

CO N TEX T

It is of t en believed t hat know ledge of w hat had occurred in Nazi Germany bef ore and during t he Second World War w as suff icient t o end eugenic policies elsew here. This is not so. Some count ries, including Canada, Sw eden and Sw it zerland, cont inued st erilisat ion on eugenic grounds unt il at least t he 1960s.9 In many count ries, t he t radit ions of polit ical t hought , w hich in a general sense might be regarded as eugenic, have cont inued in minorit y polit ics. Amongst scient ist s, eugenic ideas cont inued t o have t heir support ers. For inst ance, in 1962 an int ernat ional group of dist inguished biologist s met at t he Ciba Foundat ion t o consider ‘M an and his Fut ure’.10 The meet ing w as much preoccupied by eugenics:

H I STO RI CA L

2.6

TH E

In many count ries, alt hough not in Brit ain, programmes of t he compulsory st erilisat ion of t he ‘unf it ’ w ere inst it ut ed in t he 1920s and 1930s t o combat ‘racial degenerat ion’ and crime. It is est imat ed t hat in t he US about 30,000 people w ere st erilised. In Germany t he f igure w as probably 400,000.8 In Nazi Germany t here w as select ive breeding of t he ‘racially pure’, t he ‘eut hanasia’ of t housands of children living in inst it ut ions, and t he killing of adult s f rom f amilies t hat carried M endelian condit ions such as Hunt ingt on’s disease. Eugenics had it s crit ics, w ho argued on moral, polit ical, social and scient if ic grounds. In Brit ain, by t he 1930s, t here w as increasing opposit ion f or bot h social and polit ical reasons and because of t he lack of any evidence demonst rat ing t hat t he charact erist ics cent ral t o t he eugenic programmes w ere inherit ed t o any signif icant degree.

2

2.5

CH A PTER

because of t he part icularly high deat h rat e among off icers. This aided t he promot ion of eugenic policies in t he 1920s. In Brit ain and elsew here, t here w as a w ide consensus t hat behavioural and personalit y t rait s and moral qualit ies w ere largely det ermined by inherit ance. This w as repeat edly emphasised by eugenic educat ional programmes, w hich claimed, part icularly in t he early years of t he movement , t hat t hese charact erist ics w ere t ransmit t ed as M endelian t rait s (‘like t he coat colours of guinea pigs’).7

‘The improvement of human genet ic qualit y by eugenic met hods w ould t ake a great load of suf f ering and f rust rat ion of f t he shoulders of evolving humanit y, and w ould much increase bot h enjoyment and ef f iciency. Let me give one example. The general level of genet ic int elligence could t heoret ically be raised by eugenic select ion; and even a slight rise in it s average level w ould give a marked increase in t he number of t he out st andingly int elligent and capable people needed t o run our increasingly complex societ ies. How t o implement eugenic policy in pract ice is anot her mat t er. The eff ect s of merely encouraging w ell-endow ed individuals t o have more children, and vice versa, w ould be much t oo slow f or modern psychosocial evolut ion. Eugenics w ill event ually have t o have recourse t o met hods like mult iple art if icial inseminat ion by pref erred donors of high genet ic qualit y.’ 11

7

A post er published by t he American Eugenics Societ y, 1927.

8

Paul, D. B. (1998). Cont rolling Human Heredit y 1865 t o t he Present . Amhurst , NY: Humanit y Press.

9

It has recent ly been report ed t hat since 1996, as many as 200,000 indigenous people in Peru have been pressured int o being st erilised, as part of a f amily planning programme run by t he government , w hich off ered incent ives t o t hose w ho agreed t o be st erilised and t hreat ened t o impose f ines f or reproducing. (M ass st erilisat ion scandal shocks Peru. BBC New s Online. 24 July 2002. ht t p://new s.bbc.co.uk/1/hi/w orld/americas/2148793.st m).

10

Wolst anholme, G., edit or. (1963). M an and His Fut ure. London: Churchill.

11

Wolst anholme, G., edit or. (1963). M an and His Fut ure. London: Churchill. p. 17 Julian Huxley.

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Similarly, genet icist and Nobel Prize w inner, Hermann M uller argued t hat : ‘modern civilizat ion has inst it ut ed a negat ive f eedback f rom cult ural progress t o genet ic progress … The social devices and t he individual persuasion regarding f amily size advocat ed by old-st yle eugenics are inadequat e t o meet t he sit uat ion, except in ext reme cases of specif ic def ect s. For t he major problems concerned w it h qualit at ive charact ers, t he more ef f ect ive met hod and t he one t hat is ult imat ely more accept able psychologically, is germinal choice.’ 12 2.7

The usual met hod advocat ed f or ‘germinal choice’ w as art if icial inseminat ion by select ed donors (AID). Ot hers at t he meet ing doubt ed w het her t hese met hods w ould be accept able or w ould achieve t heir desired result s. Some quest ioned w het her human populat ions w ere det eriorat ing in genet ic t erms. They point ed out t hat IQ levels w ere rising and w ondered w het her human beings could be t rust ed t o f ormulat e long-t erm eugenic object ives.13 Tw ent y years lat er, at t he Eugenics Societ y’s 75t h anniversary meet ing, w hich f ocused on eugenic and et hical aspect s of new reproduct ive and genet ic t echniques, t here w as discussion of Robert Graham’s Calif ornian sperm bank of samples t aken f rom Nobel Prize w inners. It w as suggest ed t hat ‘t here is a case on eugenic grounds f or choosing donors w ho are above, but not great ly above, t he parent al level of int elligence.’ 14 While t he Brit ish Eugenics Societ y lost some support af t er t he Second World War, it cont inued t o at t ract prominent scient ist s, including genet icist s, t o it s meet ings int o t he 1980s. Throughout t his post -w ar period t he Societ y advocat ed volunt ary policies using such t echniques as cont racept ion, AID, carrier det ect ion of M endelian diseases and prenat al diagnosis.

2.8

The eugenic movement has had a prof ound eff ect on t he development of clinical genet ics in t he post -w ar era, w it h increasing at t empt s t o separat e genet ic counselling f rom eugenic policies. This may be seen, f or example, in t he emphasis on non-direct ive counselling in cont rast t o t he provision of advice (and t reat ment ) w hich charact erises ot her clinical medicine. The educat ional act ivit ies of t he eugenics movement may be, in part , responsible f or t he cont inuing belief s t hat some behavioural charact erist ics are largely det ermined by genet ic f act ors.15

2.9

In order t o learn f rom t he hist ory of eugenics, t here is a need f or clarit y about exact ly w hat w as w rong about past eugenic programmes: ‘For t he hist ory of eugenics t o be inst ruct ive in ensuring social just ice w it h great er know ledge about genes, and perhaps some abilit y t o alt er t hem, t he key quest ion is w het her … eugenics w as w rong in it s very incept ion. If so, any eugenics programme w ill be w rong. On t he ot her hand, if t he abuses done in t he name of eugenics do not necessarily ref lect badly on eugenic ideas t hemselves, t hen our t ask w ill be t o ensure t hat any eugenic int ervent ions of t he f ut ure avoids t hese abuses.’ 16

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12

Wolst anholme, G., edit or. (1963). M an and His Fut ure. London: Churchill. p. 261. M uller w ent on t o be associat ed w it h t he Reposit ory f or Germinal Choice, a non-prof it sperm bank t hat solicit ed donat ions f rom Nobel Prize w inners and ot her eminent scient ist s.

13

Wolst anholme, G., edit or. (1963). M an and His Fut ure. London: Churchill.

14

Cart er, C. O., edit or. (1983). Development s in Human Reproduct ion and t heir Eugenic and Et hical Implicat ions. Proceedings of t he Ninet eent h Annual Symposium of t he Eugenics Societ y. London: Academic Press.

15

Paul, D. B. (1998). Cont rolling Human Heredit y 1865 t o t he Present . Amhurst , NY: Humanit y Press.

16

Buchanan, A., Brock, D., Daniels, N. & Wikler, D. (2000). From Chance t o Choice: Genet ics and Just ice. Cambridge: Cambridge Universit y Press.

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TH E H I STO RI CA L CO N TEX T

■ The pluralism of values and our st at us as designers. Eugenic programmes are crit icised f or promot ing a part icular concept ion of human perf ect ion and f or f ailing t o appreciat e t he essent ial pluralit y of values and ideals of human excellence. In pract ice, t he usual eugenic ideal w as people like t he eugenicist s t hemselves. Buchanan et al suggest t hat eugenicist s should not be f ault ed f or f avouring individuals w it h high int elligence, or ot her such t rait s, but rat her f or t he belief s and at t it udes t hat accompanied such element s in t heir programme. For example, crime and unemployment w ere t hought t o be t he result of low int elligence, and people of low int ellect ual abilit y w ere considered of lit t le value t o t hemselves or ot hers. The pluralism of ideals and values already raises diff icult quest ions w it h regard t o select ion against serious disease: t hese problems are height ened by t he pot ent ial select ion and manipulat ion of behavioural t rait s and charact erist ics about t he value of w hich t here is even less consensus. Jonat han Glover has argued t hat t he barbarous hist ory of t he t w ent iet h cent ury makes t he improvement of human nat ure desirable.17 How ever, a count er-argument might suggest t hat some of t he w orst policies of t he t w ent iet h cent ury arose f rom t he very eff ort t o improve t he human populat ion, t hrough Nazi racial ideology or St alinist social engineering. While such excesses seem unlikely in a democracy, it remains t he case t hat our ow n ideas about w hat might be t he best w ay t o improve t he human species are limit ed by our ow n values, perspect ives and horizons.

2

■ Replacement rather than therapy. Eugenics sought to improve society by causing ‘better’ people to be conceived, rather than improving the lives, health and well-being of those already born. While eugenic policies are not alone in affecting which individuals may be conceived, many social and economic policies may do that deliberately or inadvertently, eugenics raises questions about what kinds of people should or should not be born. While one may not accept the judgements that were made in the past, to argue that, in principle, such judgement should never be made would be to condemn, among other things, all programmes for prenatal screening and diagnosis for serious medical conditions.

CH A PTER

In w hat t hey t erm an ‘et hical aut opsy’ of eugenics, Buchanan et al have ident if ied f ive possible answ ers t o t he quest ion: w hat is w rong w it h eugenics? We describe t hese in t he paragraphs t hat f ollow, draw ing largely on t he account off ered by t hese aut hors.

■ Violat ions of reproduct ive f reedoms. We have already not ed t he crimes of Nazi Germany, t he involunt ary st erilisat ion of t ens of t housands of Americans and Europeans and t he programmes of segregat ion. But it is w ort h point ing out t hat many eugenicist s, including Francis Galt on and t he Brit ish Eugenics Societ y f rom t he early 1930s did not f avour coercion.18 Today, China has a clearly eugenic M at ernal and Inf ant Healt h Law.19 But in many ot her count ries reproduct ive f reedom is suff icient ly w ell est ablished t hat t he int roduct ion of programmes f or mass st erilisat ion and ot her f orms of reproduct ive coercion seems very unlikely.20 It is w idely agreed t hat t he eliminat ion of individual choice and t he int roduct ion of coercion in reproduct ive mat t ers are t w o f eat ures of past

17

Glover, J. (1984). What Sort of People Should There Be? Harmondsw ort h: Penguin.

18

Paul, D. B. (1998). Cont rolling Human Heredit y 1865 t o t he Present . Amhurst , NY: Humanit y Press.

19

China’s M isconcept ions of Eugenics [edit orial]. (1994). Nat ure 367,1–2. The law is concerned w it h negat ive eugenics, t hat is, w it h prevent ing t hose w it h undesirable inherit ed t rait s f rom reproducing.

20

Wert z, D. C. & Flet cher, J. C. Et hical decision making in medical genet ics: w omen as pat ient s and pract it ioners in eight een nat ions. In Rat cliff , K.S. et al, edit ors. (1989). Healing Technology: Feminist Perspect ives. Ann Arbor: Universit y of M ichigan Press. But see also f oot not e 9 in t his chapt er.

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eugenic pract ices t hat make t hem morally abhorrent . Some have suggest ed, on libert arian grounds, t hat volunt arily chosen ‘qualit y cont rol’ should be an opt ion.21 It should be not ed t hat one does not have t o conclude t hat eugenics f ree of coercion is morally accept able. In Chapt er 13, w e discuss argument s against allow ing individuals w ho w ould like t o make use of t echniques of prenat al select ion f rom doing so. ■ St at ism. James Wat son, one of t he scient ist s w ho discovered t he st ruct ure of DNA, has argued t hat since st at e policies w ere responsible f or t he eugenic crimes of t he past , t he role of t he st at e in mat t ers of inherit ance should be curt ailed. How ever, as several ot hers have point ed out , t he act ions of parent s, employers and insurers, among many ot hers, can harm t hose w it h genet ic diseases.22 St at es can t ake posit ive act ions t o curb such harm. Conversely, st at es may be involved in f unding and organising services f or genet ic screening and t est ing as w ell as t he t erminat ion of pregnancies w it h f et uses f ound t o carry genet ic diseases. ■ Just ice. ‘Eugenics has proved it self hist orically t o have a cruel and alw ays a problemat ic f ait h, not least because it has elevat ed abst ract ions – t he “ race” , t he “ populat ion” , and more recent ly, t he “ gene pool” – above t he right s and needs of individuals and t heir f amilies’.23 The eugenic movement believed t hat t he human populat ion f aced a grave t hreat of ‘degenerat ion’ and t hat t his just if ied t heir programmes of segregat ion and st erilisat ion. Today, in an at t empt t o dist ance current policies f rom t hat eugenic past , a line is of t en draw n bet w een eugenics, as an int ervent ion on behalf of public healt h and w ell-being, and clinical genet ics as a service f or individuals and f amilies. But , t his is a line t hat is very diff icult t o draw clearly. Behavioural genet ics cannot disavow any social purpose, but rat her has t o ensure t hat it s goals are pursued just ly and f airly.

The impact of eugenic thought on research into human behaviour

Psychology in the first half of the tw entieth century 2.10 It is hardly surprising t hat eugenic t hought prof oundly shaped t he grow t h of development al psychology and w hat lat er became know n as behavioural genet ics. Quest ions of nat ure and nurt ure dominat ed t he developing t heories. Pioneers, such as Francis Galt on, init ially used inf ormat ion about f amily hist ory and pedigree t o argue t he heredit arian case f or bot h high and low int ellect ual abilit ies (see Figure 2.1). As w ell as measuring physical charact erist ics, Galt on devised psychological t est s w hich led t o t he development of IQ t est s. He at t empt ed t o measure t he ‘st rengt h’ of inherit ance by t he associat ion of charact erist ics in parent s and children and bet w een ot her relat ives. The pedigree t echniques w hich had proved so successf ul in t he analysis of charact erist ics associat ed w it h single genes (and, indeed, are used t o t his day f or t he diagnosis of M endelian diseases) w ere f ound not t o be eff ect ive f or t he analysis of t rait s like int elligence or height , w hich w ere increasingly described in quant it at ive rat her t han qualit at ive t erms. Each f amily member in a pedigree can be described as having, or not having, a t rait such as blue eyes or a M endelian condit ion such as Hunt ingt on’s disease. In t he early w ork, ment al capacit ies w ere described in t he same w ay, w it h individuals classif ied using t erms such as f eebleminded or as having scient if ic abilit y (see Figure 2.1). How ever, in analysing ment al capacit ies, Galt on and ot hers moved t o t he use of quant it at ive

21

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For example, Glover, J. (1984). What Sort of People Should There Be? Harmondsw ort h: Penguin.

22

For example, Dust er, T. (1990). Backdoor t o Eugenics. New York: Rout ledge.

23

Kevles, D. (1985). In t he Name of Eugenics: Genet ics and t he Uses of Human Heredit y. Berkeley: Universit y of Calif ornia Press. pp. 300–1.

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Josiah Wedgw ood

Erasmus Darw in

Galt on

2

Wedgw ood

Chart show ing the inheritance of ability Darw in

CH A PTER

Figure 2.1: The f irst f amilies of eugenics

TH E H I STO RI CA L CO N TEX T

Charles Darw in

Francis Galt on

M ale / Female

Normal

Brilliant

Scient if ic abilit y

Ot her normal children

A pedigree chart show ing t he inherit ance of abilit y in t he Wedgw ood, Darw in and Galt on f amilies w hich w as originally published by t he Eugenics Societ y in 1909. The names of prominent individuals w ere added by Rest a.* Francis Galt on (1822–1911) w as a f ounder and t he f irst President of t he Eugenics Societ y. On his deat h M ajor Leonard Darw in, son of Charles Darw in, became Secret ary of t he Societ y and lat er President . Sir Charles G. Darw in (Charles Darw in’s nephew ) w as a Vice-President and served on t he council of t he Societ y w it h such luminaries as Aubrey Lew is (psychiat rist ), Julian Huxley (biologist ), John M aynard Keynes (economist ), Richard Tit mus (sociologist ) and D.V. Glass (demographer).

*

Rest a, R. (1995). Whispered hint s. Amer. J. M ed. Genet . 59, 131–3. It w ill not escape t he not ice of readers t hat , in line w it h prejudices of t he day, no w omen are classif ied as brilliant or as having scient if ic abilit y.

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measures, like IQ scores, and applied t he new st at ist ical approaches. This research led t o t he development of herit abilit y scores, w hich are discussed in Chapt er 4. Today, IQ is seen as being polygenic (inf luenced by many genes) in cont rast w it h a disease like Hunt ingt on’s disease w hich is associat ed w it h t he mut at ion of a single gene. While pedigree met hods remain a valuable w ay t o st udy charact erist ics associat ed w it h a single gene, quant it at ive met hods are needed f or polygenic t rait s such as behavioural charact erist ics. 2.11 Galt on’s original quest ion about t he ‘st rengt h’ of inherit ance is t he same as t he cont emporary common sense underst anding of herit abilit y. This is t he ext ent t o w hich inherit ance (nat ure), on t he one hand, and environment al (nurt ure) f act ors, on t he ot her, cont ribut e t o t he development of charact erist ics such as int elligence in an individual. Does an individual ow e her high int elligence t o w hat she has inherit ed f rom her parent s or her upbringing and schooling or a part icular mixt ure of t he t w o? In f act , it t urns out t o be very diff icult t o answ er scient if ically t he quest ion posed in t hese t erms. As w e shall see in Chapt er 4, w hat research in behavioural genet ics can do is t o est imat e t he herit abilit y of a charact erist ic in a part icular group of people, not an individual. This is t he proport ion of t he variat ion in t he charact erist ic in a part icular populat ion, say t he variat ion in IQ scores f or a part icular group, and it is t his group variat ion w hich can be apport ioned bet w een inherit ed f act ors and t hose in t he environment . But , as w e shall see lat er in our discussion, t here is a cont inuing t endency t o misunderst and t he meaning of est imat es of herit abilit y. People of t en assume t hat it is t he common sense meaning of herit abilit y (or Galt on’s st rengt h of inherit ance). So, if it is st at ed t hat t he herit abilit y of IQ is 0.50, some people may assume t hat half t heir IQ (or t hat of anyone else in t hat populat ion) is cont ribut ed by t heir genes and half by t heir nurt ure. As w ill be discussed more f ully in Chapt er 4, t his is incorrect . The scient if ic meaning of an est imat e of herit abilit y of 0.50 is t hat half t he variat ion in IQ scores bet w een people in t he group appears t o result f rom genet ic variat ion bet w een t hem, and half t he group variat ion f rom diff erences in t heir environment and upbringing. 2.12 M ost of t he Brit ish scient ist s involved in t he quant it at ive st udy of individual and group diff erences in int ellect ual abilit ies in t he f irst half of t he cent ury w ho made last ing cont ribut ions t o development of t he subject , w ere prominent eugenicist s and w ere cent rally concerned w it h issues of nat ure and nurt ure.24 This t radit ion of research creat ed modern paramet ric st at ist ics and t he scient if ic st udy of behavioural genet ics. 2.13 In t he f irst half of t he cent ury t here w ere numerous st udies of int ellect ual abilit ies of t en using t w in designs and est imat es of herit abilit y. These set out t o demonst rat e t hat inherit ance played a major part in t he development of t hese charact erist ics. But such w ork w as rat her eclipsed in t he 1940s and 1950s in t he US by t he rise of behaviourist psychology. How ever, t he t radit ion cont inued in t he UK led by psychologist s such as Hans Eysenck. The behaviourist s compared input s and out put s, but t hey had lit t le int erest in eit her t he evolut ionary or development al f act ors t hat might shape t he mind/brain/body.

Psychology from the 1960s onw ards Individual diff erences 2.14 The earlier t radit ions of ‘individual psychology’ or behavioural genet ics, w hich w ere based on t echniques of quant it at ive genet ics, w ere gradually re-est ablished in t he Unit ed St at es in t he 1960s. Such w ork received enormous publicit y w it h t he publicat ion of Art hur Jensen’s

24

2 0

For example, Francis Galt on, R A Fisher, Karl Pearson and Cyril Burt .

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2 TH E H I STO RI CA L CO N TEX T

2.15 Despit e t he f act t hat Jensen’s conclusions w ere crit icised by many academics (alt hough t hey did receive support f rom ot hers such as Hans Eysenck in t he UK), t hey have been very inf luent ial. Wat ers w ere f urt her muddied because several prominent researchers in behavioural genet ics involved in t his research bot h in t he US and Brit ain accept ed support f rom overt ly racist organisat ions. Crit ics argued t hat t he inf erences t hat Jensen drew f rom est imat es of herit abilit y w ere invalid and t hat his argument s involved a not ion of genet ic det erminism t hat w as unsupport ed by evidence. Recent ly, broadly similar argument s t o Jensen’s, w hich reach generally similar conclusions relat ed t o socioeconomic diff erences in t he USA, have been put f orw ard in The Bell Curve.26 These, t oo, received w ide int ernat ional publicit y and much crit icism, but also support , f rom some social scient ist s, psychologist s and genet icist s.27

CH A PTER

art icle in t he Harvard Educat ional Review , ‘How f ar can w e boost IQ and educat ional achievement ?’ 25 Jensen’s ow n answ er t o his quest ion w as, in brief , ‘very lit t le’, as he assumed t hat int ellect ual abilit ies w ere largely det ermined by genet ic endow ment . Jensen argued on t he basis of est imat es of herit abilit y t hat diff erence in IQ scores generally f ound w hen comparing black and w hit e groups w ere t he result of genet ic diff erences bet w een t he groups. He claimed, t heref ore, t hat t hey w ere unlikely t o be able t o be changed by environment al manipulat ions, such as t he pre-school Head St art Programmes w hich at t hat t ime w ere being w idely inst it ut ed in t he US.

2.16 There cont inues t o be a popular but mist aken belief t hat t he level of herit abilit y equat es w it h t he ease or diff icult y of changing or alt ering a part icular charact erist ic, or it s immut abilit y. How ever, researchers in behavioural genet ics and psychologist s w ould now agree t hat t he w ays in w hich diff erent f act ors int errelat e in t he development of a charact erist ic are not relat ed t o it s immut abilit y. Environment al int ervent ions, be t hey social, diet ary, physiological or ot herw ise, can change t he course of genet ic diseases or, indeed, behavioural charact erist ics t hat are highly herit able. Conversely, t here are numerous examples of social and cult ural pract ices and behaviour t hat are very resist ant t o change. Evolut ionary psychology 2.17 In part as a react ion against t he behaviourism of t he 1950s and 1960s (paragraph 2.12), ot her approaches w ere developed t hat drew t o a great er ext ent on biology. One example of t his t rend is evolut ionary psychology. Evolut ionary psychology t akes it s inspirat ion f rom t he Darw inian t heory of nat ural select ion. A general aim is t o see how current pat t erns of behaviour can be underst ood in t erms of our evolut ionary hist ory. Where a part icular pat t ern of behaviour is w idespread and is seen across diff erent cult ures, it is of t en assumed t hat t here w ill have been st rong select ion pressures f avouring t he development of t hat behaviour and so t he select ion of t he part icular genet ic variant s (‘genes’) responsible f or it s development . There is t heref ore a general inf erence about processes of development in t he individual (ont ogeny) f rom t he presumed evolut ionary process (phylogeny) t hat has led t o t he w idespread occurrence of t he behaviour pat t ern. Over t he past t w o decades t he principles of evolut ionary psychology have been w idely applied t o t he st udy of human behaviour. But evolut ionary biology has alw ays had it s crit ics,

25

Jensen, A. R. (1969). How much can w e boost IQ and scholast ic achievement ? Harvard Educ. Rev. 39, 1–123.

26

Herrnst ein, R. & M urray, L. (1994). The Bell Curve: Int elligence and Class St ruct ure in American Lif e. New York: The Free Press.

27

Devlin, B., Fienberg, S. E., Resnick, D. P. & Roeder, K., edit ors. (1997). Int elligence, Genes and Success. New York: Copernicus.

28

Rose, H. & Rose, S. (2000). Alas Poor Darw in: Argument s Against Evolut ionary Psychology. London: Cape.

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part icularly f rom t he f ield of development al biology.28 One crit icism t hey make is t hat t here is no necessary connect ion bet w een a possible evolut ionary explanat ion t hat suggest s t hat select ion pressures may have inf luenced a pat t ern of behaviour in t he past , and t he processes of development t hat lead an individual t o behave in a part icular w ay in a part icular sit uat ion. Processes of development 2.18 There are of course many ot her approaches w it hin development al psychology w hich at t empt , in various w ays, t o underst and t he processes of development of behaviour in individuals and t o isolat e f act ors w hich have signif icant eff ect s. Given t he complexit y of t he processes involved, it is perhaps not surprising t hat no t heory of development is generally accept ed. While most development al psychologist s believe t hat nat ure and nurt ure are bot h involved in t he development of behavioural charact erist ics, t here is an increasing move t ow ards a variet y of t heoret ical posit ions t hat do not use t his concept ual dichot omy.

Conclusion 2.19 Behavioural genet ics w as est ablished in t he era of eugenic policies and pract ices; indeed, it f ormed a major part of t he scient if ic f oundat ions on w hich t hese policies w ere claimed t o be based and t he development of behavioural genet ics w as it self shaped by eugenic concerns. How ever, t his does not necessarily imply t hat cont emporary research on t he genet ics of behaviour is in any sense eugenic or is driven by considerat ions t hat could be considered eugenic. In f act , as w e have point ed out , part of t he reason f or t he decline in t he support of eugenic policies in many count ries f rom t he 1930s onw ards w as scient if ic research w hich demonst rat ed t hat t he policies of segregat ion and st erilisat ion of t hose deemed t o be unf it w ould not achieve t heir st at ed goals. How ever, as a number of respondent s t o our consult at ion have suggest ed, t here remains a view t hat research on t he genet ics of human behaviour, part icularly in t he area of int elligence, is necessarily eugenic or w ill lead t o t he re-est ablishment of eugenic policies. It is possible t hat cont emporary underst anding of t he herit abilit y of IQ and ot her behavioural charact erist ics, and increasing know ledge of t he processes of inherit ance of ot her t rait s, could provide a scient if ic f oundat ion f or a programme of posit ive or negat ive eugenics, w ere t here t o be t he polit ical w ill or pow er t o const ruct and implement such a policy. 2.20 We conclude t hat hist orical and philosophical st udies of eugenic pract ices and policies should be encouraged so t hat it may be clearly underst ood w hat w as, and w as not , unaccept able about t he past and t he w ays in w hich t his may, or may not , be dist inguished f rom cont emporary genet ic policies and pract ices.

2 2

Section Scient if ic background

2

Chapter Research in behavioural genet ics

3

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Introduction

GEN ETI CS

Genot ype An individual’s genot ype is his or her ent ire complement of DNA.

BEH AV I O U RA L

Research in behavioural genet ics examines t he eff ect s of genot ype and environment on a range of phenot ypic t rait s such as anxiet y, int elligence, sexual orient at ion and ant isocial behaviour.

I N

Box 3.1: What does research in behavioural genetics study?

RESEA RCH

There are diff erent w ays in w hich researchers can st udy t he cont ribut ion t hat genet ic f act ors make t o human behaviour. First , t here are observat ional st udies, w hich involve assessing and comparing relat ives such as t w ins or siblings, f amilies and adopt ed children. This t ype of research is called quant it at ive genet ics because it aims t o examine t he ext ent t o w hich variat ion in a t rait is inf luenced by genet ic f act ors in a populat ion. It uses st at ist ical met hods t o examine and compare groups of people, w it hout f ocusing on part icular genes. M ore det ail about research in quant it at ive genet ics is provided in Chapt er 4. Secondly, researchers can t ry t o ident if y diff erences in genes t hat cont ribut e t o t rait variat ion in charact erist ics or t rait s bet w een individuals. This t ype of research is called molecular genet ics and it s applicat ion t o behavioural research is explained in Chapt er 5. Thirdly, researchers can use animals t o t ry and examine t he eff ect s of part icular genes on behaviour. Chapt er 6 describes t his t ype of research. The f ocus of research in behavioural genet ics is summarised in Box 3.1.

3

3.1

CH A PTER

Research in behavioural genet ics

Phenot ype An individual’s phenot ype consist s of all his or her measurable or observable propert ies and charact erist ics aside f rom his or her genes. These could include charact erist ics such as hair colour, height and IQ score. Researchers in behavioural genet ics of t en include such diverse t rait s as marit al st at us, t ast e in music and religious belief s as part of t he phenot ype. Environment An individual’s environment is t o be underst ood very broadly. It includes everyt hing t hat inf luences an individual’s phenot ype, apart f rom his or her genot ype. Environment al f act ors include w here a person lives and how many siblings he or she has, but also biological f act ors such as t o w hich chemicals a person might have been exposed t o bef ore and af t er birt h.

3.2

Bef ore examining t he various t ypes of research and t heir advant ages and limit at ions, it is import ant t o have a clear underst anding of w hat is meant by t he suggest ion t hat genes inf luence, aff ect or cont ribut e t o human behaviour. The remainder of t his chapt er at t empt s t o do t his by addressing t he f ollow ing quest ions: ■ What are genes and how do t hey w ork? (See Box 3.2). ■ What is genet ic variat ion? ■ What do w e mean by human behaviour in t he normal range? ■ How might genes inf luence human behaviour in t he normal range? ■ How could t he behaviour of an individual be predict ed f rom inf ormat ion about his or her genot ype? 2 7

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Box 3.2: How do genes w ork? The human genome cont ains t he genet ic inf ormat ion required t o build t he human body. This inf ormat ion is held in code on t ight ly coiled t hreads of deoxyribonucleic acid (DNA). A DNA molecule consist s of t w o st rands t hat w rap round each ot her t o resemble a t w ist ed ladder – t he f amous double helix. Each st rand of DNA is made up of a st ring of unit s called nucleot ides, or bases. There are f our diff erent bases: adenine (A), t hymine (T), guanine (G) and cyt osine (C). These bases pair t oget her – A w it h T, and C w it h G. Each base pair f orms a rung of t he ladder. The w ay t hese pair t oget her causes t he st rands t o coil up int o t he spiral t w ist ed ladder (see Figure 3.1). It also allow s t he DNA t o replicat e, or copy it self .

Figure 3.1: The st ruct ure of DNA. The base pairs, A-T and C-G, f orm t he rungs of t he ladder. A gene is a segment of DNA t hat cont ains t he inst ruct ions f or making a specif ic prot ein (or somet imes ribonucleic acid (RNA)). Each set of t hree base let t ers, f or example ACG, is a code providing t he inst ruct ions t o assemble a prot ein. A gene may cont ain anyt hing f rom a f ew hundred t o over a million base pairs. Genes are assembled int o chromosomes, long st rands of DNA large enough t o be seen dow n t he microscope. A chromosome cont ains bet w een a couple of hundred and several t housand genes, arranged in a specif ic order end-t o-end, w it h sect ions of spacer DNA, w hich does not code f or any genes, in bet w een. Humans have 22 pairs of chromosomes plus t he sex chromosomes (XX in t he f emale, XY in t he male). One set is f rom t he mot her and one f rom t he f at her. Toget her, t hese 23 pairs make up t he human genome. It is est imat ed t hat each human has about 30,000–40,000 genes, and around six billion base pairs of DNA. Prot eins carry out t he w ork of a cell. They are made of various combinat ions of 20 chemical building blocks, called amino acids. The sequence of t he gene det ermines t he order t hat t hese blocks assemble t oget her, and hence w hich prot ein is made (see Figure 3.2). Diff erent prot eins have diff erent specialised f unct ions, such as making muscle, binding oxygen f rom t he air, t ransmit t ing nerve impulses, and breaking dow n f ood subst ances. M any prot eins are enzymes, w it h t he specialised f unct ion of synt hesising, breaking dow n or alt ering ot her chemical molecules. Some of t he product s of genes, and some of t he subst ances made by t hese product s, are ‘messengers’ export ed by cells t o have eff ect s on ot her cell t ypes. For example, hormones are made in specialised endocrine glands, and can st imulat e or suppress t he f unct ions of ot her cells in dist ant organs.

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Gene 2

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Gene 1

Gene 3

3

Protein 2

Protein 3

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Protein 1

Figure 3.2: Genes make prot eins

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The human body consist s of many diff erent t ypes of cell, each w it h a specialised f unct ion, f or example skin cells and liver cells. These cells rely on diff erent prot eins t o perf orm t heir specialised jobs. Nearly every cell in t he body has t he same genet ic mat erial. But w hat makes cells diff er f rom each ot her is not w hich genes t hey have, but w hich genes are act ive in t hat cell. A prot ein, or part of a prot ein, is only produced w hen it s corresponding gene is act ive. The product ion of prot eins is also called gene expression. A gene is act ive w hen RNA, t he int ermediat e bet w een DNA and prot ein, is being synt hesised. It is not yet complet ely underst ood w hat det ermines w het her a gene is act ive or inact ive, t hough t he f unct ion of some genes is (t hrough t heir encoded prot eins) t o t urn ot her genes on and off . It is increasingly recognised t hat secondary modif icat ions t o t he chemical st ruct ure of t he original gene and it s associat ion w it h specif ic prot eins are import ant f act ors in t his process. The environment of t he cell may inf luence t hese so-called epigenet ic eff ect s, w hich can be st ably inherit ed t hrough cell divisions and even t hrough generat ions.* ,†

Pennisi, E. (2001). Behind t he scenes of gene expression. Science 293,1064–7. For an account of t he complex et ymology of t he t erm ‘epigenet ics’, see Wu, C.-T. & M orris, J. R. (2001). Genes, genet ics, and epigenet ics: a correspondence. Science 293,1103–5. Images in t his box are reprint ed w it h permission f rom Roche Genet ics. ht t p://w w w.roche.com/pages/rgg/science-gengencdrom% 5b2% 5d+jpg_page1.ht ml (11 June 2002).

What is genetic variation? 3.3

A comparison of t he DNA sequence of corresponding chromosomes bet w een t w o people chosen at random w ould show t hat t he DNA sequences w ere almost , but not precisely, ident ical. On average, one in every 1,300 posit ions along t he sequence w ill have diff erent bases present at t he corresponding posit ions. For example, some people might have an ‘A’ base w hereas ot hers have a ‘G’ base at a part icular posit ion. These t w o alt ernat ive possibilit ies are t ermed alleles. If t he rarer of t he t w o alleles is present in at least 1% of chromosomes in a populat ion, it is t ermed a polymorphism. The simplest t ype of variat ion, w here a single let t er is subst it ut ed f or anot her (as in t he example above), is called a single nucleot ide polymorphism (SNP). Cont inuing w it h t his example, an individual’s DNA sequence at a part icular point could be AA, GG or AG, because t he chromosomes occur in pairs. In t he f irst t w o sit uat ions, t he person is called a homozygot e because bot h let t ers in t he pair of chromosomes are t he same. In t he t hird, t he person is called het erozygot e because bot h t he let t ers at t his posit ion are diff erent . M ost people are het erozygous at 2 9

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over 20 million diff erent sit es in t heir genome. Included in t his t ot al w ould be a signif icant proport ion of SNPs, est imat ed t o number about 11 million.1 3.4

Much of this variation occurs in the stretches of DNA situated between the genes and probably has no important effect on the organism. However, variation occurring near to, or within, genes could affect either the amount of protein made in a particular cell, or the sequence of amino acids in the protein. If this variation is found to correlate with a particular behaviour, or other trait, it is termed a susceptibility allele. The difficulty for the researcher is in sifting out, from the millions of polymorphisms in the human genome, the smaller number, possibly thousands, that actually contribute to variation between individuals, and which are presumed to underlie the contribution of genetic factors to differences between people.

3.5

Such ’genet ic variat ion’ arises in t he f irst place because of damage t o DNA or mist akes in copying DNA during replicat ion. This process is called mut at ion. M ut at ion can occur in any cell, but is of part icular concern w hen it aff ect s eggs or sperm, as t his allow s t he variant alleles t o be passed on t o f ut ure generat ions. How ever, new alleles t hat have major adverse eff ect s w ill be eliminat ed rapidly f rom a populat ion, because individuals carrying t hose alleles are less likely t o reproduce. How, t hen, can part icular alleles become common in t he populat ion and yet inf luence genet ic suscept ibilit y? Combinat ions of t he f ollow ing processes inf luence t he f requency of alleles: ■ Age of onset of t he t rait . An allele w hose major eff ect occurs af t er t he age of reproduct ion w ill be subject t o very lit t le select ion because individuals carrying t he allele w ill already have had t he pot ent ial t o t ransmit it t o t heir off spring by t he t ime t hat t he eff ect becomes apparent . ■ Chance f act ors in t he cont ext of w eak select ion. The rapid grow t h of t he human populat ion f rom relat ively small numbers of individuals, and chance f act ors inf luencing reproduct ive success, could t oget her enable mildly harmf ul alleles t o reach a signif icant f requency in t he populat ion (t his is t ermed genet ic drif t ). ■ St rengt h of select ion in relat ion t o genot ype. Select ion of an allele at t he level of t he populat ion w ill be st rong if t he t rait manif est s in t he het erozygot e (dominance) but w eaker if it manif est s only in t he homozygot e (recessivit y). A special case is w hen t he het erozygous st at e has a survival benef it over eit her homozygot e (t his is t ermed het erozygot e advant age).2 ■ Diff erent select ion in diff erent environment s. Alleles may be benef icial in some environment al circumst ances and harmf ul in ot hers. For example, t hey may prot ect f rom st arvat ion but predispose t o obesit y. Environment al variat ion may t hen give rise t o a balanced polymorphism bet w een t w o alleles. Whet her an allele is considered benef icial or harmf ul w ill depend on t he cont ext .

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Kruglyak, L. & Nickerson, D. A. (2001). Variat ion is t he spice of lif e. Nat . Genet . 7, 234–6. The remainder consist s of single nucleot ide variat ions present on less t han 1% of chromosomes and ot her t ypes of variat ion such as simple sequence repeat s. The ident if icat ion of t hese SNPs has been a signif icant f ocus of t he Human Genome Project : already over 2.7 million are know n (f igure f rom dbSNP, available at : ht t p://w w w.ncbi.nlm.nih.gov/SNP/snp_summary.cgi (3 July 2002)) and it is likely t hat virt ually all t hese SNPs w ill be ident if ied w it hin t he next f ew years.

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A w ell-know n example is t he sickle cell mut at ion of ß globin. The homozygous st at e (ß A/ß A) causes t he blood disorder sickle cell anaemia, but t he het erozygous st at e ( ß S/ß A) prot ect s against malaria and has a survival advant age over t he normal (ß A/ß A) st at e in malaria-inf est ed count ries. The t w o alleles (ß A/ß S) are maint ained in t he populat ion because t heir net eff ect is quit e neut ral. The delet erious eff ect s become apparent in disease-based st udies and benef icial eff ect s may only be discovered lat er f rom populat ion-based st udies.

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■ Pleiot ropy. Suscept ibilit y alleles may aff ect diff erent t rait s, w hich are subject t o diff erent select ion pressures. For example, homozygosit y f or t he 2 allele of a blood prot ein called apolipoprot ein E predisposes an individual t o developing excessive f at levels in t he blood, but also seems t o prot ect t he brain against t he development of Alzheimer’s disease.3

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What is meant by normal variation in human behaviour? Many human traits are not viewed as either present or absent, but rather as continuously distributed measures which each individual in the population will show to a greater or lesser extent (for example, height, blood pressure, aggressiveness and intelligence, as measured by IQ t est scores). These characteristics vary from person t o person in a populat ion and t his variabilit y is know n as populat ion variat ion. When the frequency of t he eff ect is plot t ed against t he magnit ude, many of t hese cont inuously dist ribut ed charact erist ics show a bell-curve dist ribut ion Low and high scorers at t he ‘t ails’ of t he dist ribut ion t hat is know n as a normal dist ribut ion (see Figure 3.3: A normal dist ribut ion curve Figure 3.3).

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Scriver, C. R., Beaudet , A. L., Sly, W. S. & Valle, D. (2001). The M et abolic and M olecular Base of Inherit ed Disease. 8t h ed. New York: M cGraw -Hill. pp. 2835–62 and 5875–99.

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Recombinat ion is t he process by w hich chromosomes are broken and t he f ragment s rejoined in new combinat ions, and is a vit al aspect of reproduct ion and inherit ance.

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Some t rait s t hat are genet ically inf luenced may have bot h posit ive and negat ive aspect s in an individual. For example, it has been hypot hesised t hat people w it h manic depression are also more creat ive (f or an exposit ion of t his t heory see Jamison, K. R. (1996). Touched Wit h Fire: M anic-Depressive Illness and t he Art ist ic Temperament . New York: The Free Press). Alt ernat ively, t he desirabilit y of a t rait may be perceived diff erent ly in diff erent individuals. For example, high scores on t he Psychot icism dimension of personalit y t est s have been show n, in non-psychot ic individuals, t o be associat ed w it h high creat ivit y.

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3.7

BEH AV I O U RA L

It is import ant t o not e t hat genet ic variat ion in t he normal range is usually neit her good nor bad. Genet ic variat ion causes people t o have diff erent nat ural hair colours or diff erent blood groups, but t his is not t o say t hat a part icular hair colour or blood group is ‘bet t er’ t han anot her. In t he case of genet ic mut at ions t hat cause diseases such as cyst ic f ibrosis or Hunt ingt on’s disease, it might be reasonable t o say t hat t hese mut at ions are delet erious. Wit h most f orms of genet ic variat ion, all one can say is t hat diff erences exist , not t hat t hey are delet erious or advant ageous.5

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■ Genet ic hit ch-hiking. When select ion of an allele occurs, t he adjacent segment of DNA is passively select ed w it h it , only lat er becoming separat ed by rare recombinat ions.4 This, and ot her f act ors, such as t he mixing of populat ions, gives rise t o linkage disequilibrium, w hich means t hat alleles may appear t o be associat ed w it h variat ion in a phenot ype w it hout t hemselves causing t hat variat ion.

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3.8

M ost individuals score somew here in t he middle of t he populat ion dist ribut ion, but a cert ain percent age w ill f orm t he ‘t ails’ of t he dist ribut ion (i.e. very high or low scorers). St at ist icians can quant if y t he ‘spread’ of scores in t his dist ribut ion and t his st at ist ic is know n as variance. Ext remes of variat ion can be associat ed w it h an increased risk of adverse out comes, f or example high blood pressure is associat ed w it h an increased risk of a st roke, but t hey are not necessarily associat ed w it h illness. Such ext remes might have a number of diff erent explanat ions. In t he case of high blood pressure, t his could be due t o excessive int ake of salt in t he diet , a combinat ion of diet ary and w eak genet ic f act ors, or a single mut at ion causing f ailure of t he kidney t o eliminat e salt . In t he f ield of behavioural t rait s, ext reme scores f or t rait s such as neurot icism or aggression may be associat ed w it h an increased risk of adverse out comes such as ment al illness.

‘A gene for X’? 3.9

Having underst ood t hat t here are diff erences in bot h t he genot ypes and t he phenot ypes of individuals, t he next challenge is t o underst and how genet ic variant s might be relat ed t o t he variat ions in behavioural and personalit y t rait s. It is common t o hear of research t hat claims t o ident if y a ‘gene f or aggression’ or a ‘gene f or homosexualit y’. But how could our genes cause us t o act in a part icular w ay? What is really meant by saying ‘a gene f or X’?

3.10 We all have a w orking know ledge of t he syst em of causal relat ions t hat enables each of us t o f unct ion in our complex w orld. The accumulat ion of t his know ledge begins early in lif e. Once a child reaches a cert ain age he w ill push an object off t he t ray of his high chair and observe it f alling t o t he f loor. On discovering t he eff ect s of gravit y, he w ill repeat t he experiment over and over again t o t est t he discovery beyond all reasonable doubt . Unf ort unat ely, t he concept s of causat ion t hat are est ablished early in lif e are t oo rudiment ary t o serve w ell as t he basis f or scient if ic t heories. 3.11 A usef ul w ay t o underst and w hat is meant by a cause is t o t hink of it as a f act or t hat increases t he chance t hat an event occurs. So, w hen t he child pushes it s t oy of f it s highchair, various f act ors combine t o make t he t oy f all t o t he f loor, including t he movement and f orce of t he child’s hand, t he w eight of t he t oy and t he ef f ect of gravit y. Toget her, t hese f act ors make it ext remely likely t hat t he t oy w ill f all on t he f loor: t hey raise t he chance of t his happening t o a very high degree. It is easy t o assume t hat t here is a one-t o-one correspondence bet w een cause and ef f ect ; t hat one cause leads t o one ef f ect . How ever, as t he example of t he child’s t oy show s, t here are usually a number of causal f act ors t hat come t oget her t o make cert ain event s more likely. These t w o point s, t he exist ence of more t han one causal f act or in a part icular sit uat ion, and t he idea t hat causes raise t he chance of somet hing happening w it hout necessarily making t hat out come inevit able or 100% likely t o occur, are import ant in underst anding how genet ic f act ors can inf luence behaviour. 3.12 There are some genet ic mut at ions t hat do seem alw ays t o be present w hen disease occurs, such as t he genet ic mut at ions t hat are associat ed w it h cyst ic f ibrosis and Hunt ingt on’s disease. In t hese diseases, an alt erat ion in a part icular gene can be said t o have caused t he disorder. Wit hout t he genet ic mut at ion, t he individual w ould not have t he disorder, w hich means t hat t he genet ic mut at ion is a necessary condit ion f or t hat disorder. In addit ion, f or a very small subgroup of single-gene disorders, f or example Duchenne’s muscular dyst rophy, t he genet ic mut at ion is also a suff icient condit ion: just possessing t he mut at ion makes it cert ain t hat you w ill have t he disorder. How ever, it is w ort h not ing t hat even in apparent ly clear cases, t he connect ion bet w een t he gene alt erat ion and t he disorder is not

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■ These mult iple genet ic f act ors may int eract w it h each ot her and have diff erent eff ect s depending on w hich ot her f act ors are present in t he individual’s genot ype.

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■ M ore t han one genet ic f act or usually cont ribut es t o a part icular t rait .

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3.14 The connect ion bet w een genes and diseases is f ar f rom st raight f orw ard, and t he relat ionship bet w een genes and behaviour is even more complicat ed. It is of t en diff icult t o est ablish w hich genes cont ribut e t o a t rait and how t hey do so because:

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3.13 Diseases in w hich t here is a clear connect ion bet w een a part icular genet ic mut at ion and a disorder are comparat ively rare. M ost disorders, such as breast cancer, heart disease and diabet es, are much more complicat ed. Of t en, a genet ic mut at ion or suscept ibilit y allele w ill cause a disease only in t he presence of cert ain environment al f act ors, such as st ress or a part icular diet . The relat ionship bet w een genet ic and environment al f act ors in causing disease can be illust rat ed by a disorder called alpha-1 ant it rypsin def iciency. If an individual w it h t his genet ic disorder t akes up smoking, he or she is much more likely t o develop a f orm of a chronic lung disease called emphysema, because of a genet ic mut at ion w hich prevent s t he product ion of a normal f orm of a prot ein in t he lung t hat prot ect s against inf lammat ion. How ever, if t he individual never smokes, it is probable t hat he or she w ill never develop emphysema and may be able t o have a relat ively healt hy lif e.

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simple. Wit h Hunt ingt on’s disease, once t he mut at ed gene is ident if ied in an individual, all one can say is t hat t he disorder w ill appear. Know ledge of t he genet ic mut at ion does not enable one t o say how serious t he disease w ill be f or a part icular individual, t he precise sympt oms t hey w ill experience, or exact ly w hen it w ill arise in t heir lif et ime.

■ As w ell as genet ic f act ors, many non-genet ic (environment al) f act ors may cont ribut e t o t he manif est at ion of a t rait . ■ These environment al f act ors may also int eract w it h each ot her. ■ The genet ic f act ors may aff ect w hich environment al f act ors have an eff ect . (This is called gene–environment int eract ion: see Box 3.3). ■ Conversely, environment al f act ors may aff ect w hich genet ic f act ors have an eff ect . ■ Cert ain genet ic and environment al f act ors may go hand in hand. (This is called gene–environment correlat ion: see Box 3.3). ■ A prot ein may be modif ied af t er it has been produced f rom a gene, and t his can alt er it s f unct ion. ■ Genes do not have a cont inuous eff ect in our bodies. They may be t urned on and off , bot h during our overall development and w it hin t he lif et ime of an individual cell. So, w hile it might be correct t o say t hat a part icular genet ic variant is part of t he cause of a part icular t rait , or t hat it is one causal f act or, it w ill seldom be t he only cause, nor is it likely t o be eit her a necessary or suff icient condit ion f or t he t rait t o be manif est ed. Furt hermore, even if part icular genes t hat cont ribut e t o a t rait can be ident if ied, t his is only a small part of t he st ory. There is st ill a need t o underst and t he very indirect pat hw ay 3 3

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bet w een a gene, a part icular prot ein and an individual scoring highly on an IQ t est or having an aggressive personalit y. Our underst anding of t hese causal pat hw ays is at an even earlier st age t han our underst anding of w hich genes inf luence behavioural t rait s, w hich is it self ext remely limit ed.6 3.15 In an eff ort t o overcome t his diff icult y, some research f ocuses on ‘int ermediat e’ t rait s t hat are relat ed t o t he phenot ype in quest ion but are in some sense ‘nearer’ t he biological mechanisms and can be more object ively measured.7 For example, in research on cognit ive abilit y, such int ermediat e t rait s may include elect rophysiological measures of brain f unct ion, behavioural measures of t he speed at w hich inf ormat ion is processed or behavioural measures of t he capacit y of w orking memory in an individual (such as perf ormance on t asks of verbal and spat io-visual w orking memory).8

Box 3.3: The relationship betw een genes and the environment Gene–environment correlat ion It is somet imes assumed t hat genet ic and environment al inf luences act independent ly and addit ively: t hat separat e inf luences add up in a linear manner t o make a given out come more likely. How ever, genes and environment al f act ors can be correlat ed, or int erdependent . Children not only inherit genes f rom t heir parent s but are also exposed t o environment s t hat are inf luenced by t heir ow n and t heir parent s’ genet ic make-up. Thus, f or example, sociable parent s not only pass on genes t o t heir children but may also provide an environment t hat encourages t he development of sociabilit y in t heir children. This is know n as passive gene–environment correlat ion. A sociable child may act ively seek out sit uat ions t hat serve t o f urt her increase sociabilit y (act ive gene–environment correlat ion) or evoke responses f rom ot hers t hat increase sociabilit y. In bot h cases, t he exist ence of t he genet ic variant is linked t o t he presence of a part icular t ype of environment . Gene–environment int eract ion Genet ic and environment al f act ors may int eract non-addit ively t o inf luence charact erist ics. That is, t he impact of environment al f act ors may diff er depending on a person’s genet ic makeup. For f act ors t hat are correlat ed, det ect ing int eract ion using st at ist ical met hods can be diff icult . Large samples are needed. Nevert heless, st udies of t w ins have show n t hat t he impact of lif e event s on, f or example, depression varies depending on an individual’s genet ic suscept ibilit y.*

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Kendler, K. S. et al. (1995). St ressf ul lif e event s, genet ic liabilit y and onset of an episode of major depression in w omen. Am. J. Psychiat . 152, 833–42; Silberg, J., Rut t er, M ., Neale, M . & Eaves, L. (2001). Genet ic moderat ion of environment risk f or depression and anxiet y in adolescent girls. Brit . J. Psychiat . 179, 116–21. See also Kendler, K. S. (2001). Tw in st udies of psychiat ric illness: an updat e. Arch. Gen. Psychiat r 58, 1005–14 f or a review of gene–environment int eract ion in research in behavioural genet ics.

Rut t er, M . & Silberg, J. (2002). Gene–environment int erplay in relat ion t o emot ional and behavioural dist urbance. An. Rev. Psychol. 53, 463–90.

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These int ermediat e t rait s are somet imes called endophenot ypes.

8

See f or example, de Geus, E. J., Wright , M . J., M art in, N. G. & Boomsma, D.I. (2001). Genet ics of brain f unct ion and cognit ion. Behav. Genet . 31, 489–95.

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3.16 Any descript ion of a human act ion can be set at a level t hat includes inf ormat ion about t he biological charact erist ics of t he individual. For example, t he f ollow ing descript ions could all correct ly ref er t o t he same act :

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Describing human behaviour

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■ The man’s leg muscles cont ract ed and t hen relaxed. ■ The man moved his leg.

In t he example above, if one w ant s t o admonish t he man f or kicking t he dog, an explanat ion at t he neural or physiological level is unlikely t o be relevant . We ret urn t o t his import ant issue in t he last sect ion of t his Report , in t he cont ext of moral and legal responsibilit y.

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‘It is a w ell know n f act t hat w e describe as t he cause of an event t hat part icular condit ion by w hich w e hope t o cont rol it .’ 9

BEH AV I O U RA L

3.17 Thus, it could be said t hat t he movement of t he man’s muscles caused him t o kick t he dog, or t hat t he movement of his leg caused him t o kick t he dog. If one broadens a descript ion f ar enough, it w ill cert ainly include inf ormat ion about t he physiological charact erist ics of t he individual, since t hese w ill be involved in any human act ion. The import ant quest ion is: w hich w ay of describing or underst anding t he act is t he most usef ul? If genet ic f act ors are one aspect of causal explanat ions of human behaviour, w hat import ance should be accorded t o t hem? The answ er is likely t o depend on w hat use t he quest ioner w ant s t o make of t he inf ormat ion:

I N

■ The man kicked t he dog.

RESEA RCH

■ The man’s brain sent messages t o his leg muscles.

Predicting human behaviour from genetic information 3.18 Even if it is not know n precisely how a genet ic variant cont ribut es t o a behavioural t rait , it might be possible t o predict how likely it is t hat individuals w it h t hat genet ic variant w ill display t he t rait in quest ion. Here, it is import ant t o diff erent iat e bet w een predict ing t he f ut ure development of a phenot ypic t rait or specif ic behaviour, and measuring a phenot ypic t rait t hat is already est ablished in an individual and can be observed. For example, if t here w ere a genet ic variant , or group of genet ic variant s, know n t o be associat ed w it h low er or higher int elligence, it w ould be possible t o measure t he genot ype of a baby and t o make some predict ion of t he IQ t hat t he baby w ill have as an adult . Alt ernat ively, measuring t hat genot ype in an adult might enable t he current IQ of t he adult t o be est imat ed. A t hird scenario f or t he predict ive use of genet ic inf ormat ion w ould be t o predict t he likelihood of t he f ut ure occurrence of a specif ic act linked t o a behavioural t rait , f or example an act of aggression.10 3.19 How ever, in w hat ever cont ext t he t erm predict ion is being used, it is highly unlikely t hat individual genet ic variant s w ill of t en be accurat e predict ors of behavioural t rait s. It is not 9 10

Bart on Perry, R. (1926). General Theory of Value. Cambridge, M A: Harvard Universit y Press. p. 394. It is pert inent t o not e here t hat non-genet ic inf luences are of t en used in at t empt s t o predict behaviour, f or example correlat ions bet w een f amily environment and ant isocial behaviour. These are discussed f urt her in Chapt er 14.

3 5

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

know n how many genes w ill account f or t he genet ic inf luence on a t rait t hat is normally dist ribut ed, even if t hat genet ic inf luence appears t o be subst ant ial. Behavioural t rait s are complex, and are likely t o be t he result of t he expression of many diff erent genes, w hich int eract w it h each ot her and w it h t he environment . No single gene is likely t o account f or more t han a small proport ion of t he t ot al variance of a given t rait . Furt hermore, even if it w ere possible t o ident if y all t he genes t hat cont ribut e t o t he herit able component of t he t rait , t he predict ive pow er w ould st ill be very limit ed. In view of exist ing evidence f rom st udies of monozygot ic (M Z) t w ins, it appears t hat such genet ic predict ions of behavioural t rait s might be able t o account f or at most 50% of t he variance (see t he review s of t he evidence in Chapt ers 7–10 f or det ails of part icular st udies). This w ould st ill leave at least half t he variance in t rait scores unpredict able. Whet her t his environment al port ion of t he variance w ill become predict able depends upon f ut ure advances in underst anding w hich variables give rise t o environment al variance. This is as yet virt ually unexplored t errit ory.

Conclusion 3.20 The complexit y of human behaviour and t he diff icult ies in underst anding how genes are involved may seem overw helming. There is w ide agreement t hat genes do have an indirect eff ect on behaviour. How ever, some comment at ors have suggest ed t hat any at t empt t o underst and t he processes by w hich genes inf luence behaviour w ill cert ainly f ail. We disagree. We consider t hat it is neit her a t heoret ical nor a pract ical impossibilit y t o ident if y genes t hat cont ribut e t o behavioural t rait s and t o underst and some of t he mechanisms by w hich t hey do so. How ever, w e not e t hat t erminology such as ‘a gene f or X’ or ‘a set of genes f or X’ is very misleading because it f ails t o convey t he complexit y of t he role of genet ic f act ors in causal explanat ions of human behaviour. Genes det ermine w hich prot eins are made. They do not det ermine w hich behavioural or personalit y t rait s an individual possesses. Furt hermore, t he product of an individual gene w ill only very rarely be direct ly relat ed t o a complex behavioural charact erist ic. It w ill normally int eract w it h many ot her genes and w it h many non-genet ic f act ors, w hich means t hat t he predict ive capabilit ies of t est s f or any single or small number of genes w ill in general probably be quit e limit ed. Nonet heless, t he prot eins t hat genes make and t he w ay t hese aff ect our bodies and brains w ill be one part of an explanat ion of human behaviour.

3 6

Chapter Quant it at ive genet ics: measuring herit abilit y

4

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

The f ield of quant it at ive genet ics originat ed around 1920, f ollow ing st at ist ical demonst rat ions t hat t rait s w hich are normally dist ribut ed can arise f rom t he act ion of mult iple genes, each w it h relat ively small eff ect s (eit her increasing or decreasing t he value of t he t rait ).1 Various complex st at ist ical t echniques are employed in such research. In t his chapt er, w e explain t he concept of herit abilit y, but do not provide a det ailed account of t he st at ist ical met hods.2 We t hen go on t o describe t he t hree w ays in w hich dat a about human behaviour are obt ained in t his f ield of research, namely t w in, adopt ion and f amily st udies.

4.2

Inf luences on t he t ot al populat ion variat ion t hat is observed f or a part icular charact erist ic can be subdivided int o diff erent component s: Genet ic inf luences Environment al inf luences Gene–environment correlat ion (see Box 3.3) Gene–environment int eract ion (see Box 3.3)

The f ollow ing paragraphs 4.3 – 4.12 explain how t hese f act ors are account ed f or, st at ist ically, in quant it at ive research.

4.3

Quant it at ive research t echniques can be used t o est imat e t he inf luence of unspecif ied genet ic f act ors on behaviour. This is done by using a st at ist ical concept called ‘herit abilit y’, w hich w as f irst derived by plant breeders t o help t hem reproduce desirable charact erist ics in agricult ural product s such as corn and w heat . It is a complicat ed concept t hat can be used in various w ays. It is f requent ly misint erpret ed by scient ist s and ot her comment at ors on research in behavioural genet ics.3

4.4

There is a common sense not ion of herit abilit y or inherit ance t hat is concerned w it h t he ext ent t o w hich part icular charact erist ics in an individual are t he result of w hat one inherit s (nat ure), t he environment and w orld one grow s up in (nurt ure) or some combinat ion of t hese t w o (see paragraph 2.10). M ost development al psychologist s adopt a perspect ive of ‘int eract ionism’ – a process of development involving bot h f act ors. In t he cont ext of research in behavioural genet ics, how ever, herit abilit y has a more precise st at ist ical def init ion. This def ines herit abilit y as a st at ist ical rat io t hat , f or a given quant it at ive charact er and against a f ixed environment al background, est imat es t he proport ion of t he observat ional diff erences in t hat charact erist ic across a populat ion t hat can be at t ribut ed

1

See paragraphs 2.10-2.11

2

For f urt her inf ormat ion in t his area, see: Carey, G. (2002). Human Genet ics f or t he Social Sciences. London: Sage Publicat ions; Plomin, R., DeFries, J. C., M cClearn, G. E. & M cGuff in, P. (2000). Behavioral Genet ics. 4t h ed. New York: Wort h.

3

For a very clear discussion of concept s of herit abilit y, see Daniels, M ., Devlin, B. & Roeder, K. Of genes and IQ. In Devlin, B. et al. (1997). Int elligence, Genes and Success. New York: Copernicus.

H ERI TA BI LI TY

Genetic influences on variation

M EA SU RI N G

■ ■ ■ ■

GEN ETI CS:

How is population variation examined using genetic studies?

Q U A N TI TATI V E

4.1

4

Introduction

CH A PTER

Quant it at ive genet ics: measuring herit abilit y

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

t o genet ic inf luences. It is a st at ist ic t hat ref ers solely t o a group of individuals and does not concern t he process of development in t he individual. 4.5

Est imat es of herit abilit y may be divided int o t w o t ypes, w hich depend on t he w ay in w hich variat ion w it hin a populat ion is account ed f or. There are f our aspect s of variat ion: addit ive genet ic variance, variance due t o genet ic int eract ion (epist asis), variance due t o int eract ion bet w een alleles (dominance), and variance due t o environment al causes. Narrow -sense herit abilit y is def ined as t he proport ion of variance t hat can be at t ribut ed t o t ransmissible genet ic f act ors. Narrow -sense herit abilit y measures t he part of variance at t ribut able in a populat ion t o t he addit ive eff ect of genes, independent ly of int eract ion eff ect s bet w een alleles, bet w een loci and bet w een t he genet ic make-up and t he environment . This provides a st at ist ical est imat e t o answ er t he quest ion t hat an animal or plant breeder w ill ask: if select ive breeding is applied f or a part icular charact erist ic, w ill it w ork?

4.6

There is a diff erent concept of herit abilit y, w hich is also used in research in behavioural genet ics t hat examines human populat ions, know n as broad-sense herit abilit y. This deals w it h t he t ot al variance due t o genet ic diff erences, w hat ever t heir origin (addit ive or int eract ive). Herit abilit y in t he broad-sense does not yield a f igure t hat is predict ive and t heref ore helpf ul t o a breeder of plant s or animals. Nor, of course, does it answ er t he common sense quest ion about t he ext ent t o w hich genet ic f act ors and environment al f act ors inf luence t he development of charact erist ics in an individual. The est imat e of herit abilit y most commonly used in research st udies is narrow -sense herit abilit y, w hich account s only f or addit ive genet ic variance. (All f igures f or herit abilit y quot ed in t his Report are narrow -sense values, unless st at ed ot herw ise).

4.7

It is vit al t o underst and t hat neit her concept of herit abilit y allow s us t o conclude anyt hing about t he role of heredit y in t he development of a charact erist ic in an individual. Herit abilit y ref ers t o t he proport ion of variat ion in t he populat ion at t ribut able t o genet ic inf luences. Thus, f or example, an est imat e of herit abilit y of 0.60 does not mean t hat 60% of a part icular person’s t rait is explained by t heir genes. What it does mean, is t hat in a given populat ion t hat varies f or a part icular t rait , 60% of t hat variat ion across t he w hole populat ion is t he result of dif f erences in t heir genot ypes. As herit abilit y is a proport ion of t he t ot al variance, t he est imat e w ill vary depending on t he variat ion in t he populat ion of genet ic and environment al f act ors. For example, if t here is a populat ion of individuals w ho are genet ically ident ical f or all relevant genes cont ribut ing t o a given t rait (t hat is, t hey all carry t he same alleles f or t hose genes; clearly a hypot het ical sit uat ion), t he narrow -sense herit abilit y f or t he phenot ypic charact erist ic relat ed t o t hose genes w ould be zero, because any dif f erences must , by def init ion, be at t ribut ed t o environment al f act ors.

4.8

It is import ant t o dist inguish herit abilit y f rom genet ic det erminat ion. Novel environment al changes might have dramat ic consequences on a phenot ype. A st andard example is height . The herit abilit y of height in most populat ions is probably over 0.90, t hat is t o say, 90% of variat ion in height in most human populat ions can be at t ribut ed t o genet ic f act ors.4 But t he

4

4 0

See f or example, Phillips, K. & M at heny, A. P., Jr. (1990). Quant it at ive genet ic analysis of longit udinal t rends in height : preliminary result s f rom t he Louisville Tw in St udy. Act a Genet . M ed. Gemellol. (Roma) 39: 1,143–63; Carmichael, C. M . & M cGue, M . (1995). A cross-sect ional examinat ion of height , w eight , and body mass index in adult t w ins. J. Geront ol. A Biol. Sci. M ed. Sci. 50, 237–44; Preece, M . A. (1996). The genet ic cont ribut ion t o st at ure. Horm. Res. 45 Suppl 2, 56–8; Silvent oinen, K., Kaprio, J., Lahelma, E. & Koskenvuo, M . (2000). Relat ive eff ect of genet ic and environment al f act ors on body height : diff erences across birt h cohort s among Finnish men and w omen. Am. J. Public Healt h 90, 627–30.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

M EA SU RI N G H ERI TA BI LI TY

4.10 M any st udies in t his f ield have report ed t hat t he proport ion of variat ion in behavioural t rait s t hat can be at t ribut ed t o f act ors shared by f amily members is relat ively low. These f indings have been used t o claim t hat an individual’s shared environment , part icularly t he f amily, has lit t le eff ect on his or her behaviour.6 Int erest ingly, an except ion t o t his f inding is in t he case of ant isocial behaviour. Signif icant eff ect s of shared environment s are rout inely report ed in research in behavioural genet ics in t his area. M oreover, many researchers have now reject ed t he conclusion t hat t he role of t he f amily in aff ect ing behaviour is unimport ant .7

GEN ETI CS:

Environment al variance includes a proport ion of variance t hat can be explained by shared or common environment al inf luences and a remaining proport ion account ed f or by nonshared environment al f act ors, random eff ect s and error. The t erms ‘shared’ and ‘nonshared’ environment ref er t o t he eff ect s of t he environment al inf luence, not t heir origins (as previously assumed by many researchers); t hat is w het her t hey increase or decrease similarit y bet w een f amily members f or a given charact erist ic. For example, social disadvant age is an environment al f act or t o w hich all f amily members are exposed. How ever, it s eff ect s on a part icular behaviour may appear as ‘non-shared’ in genet ic analyses if social disadvant age has a diff erent eff ect on each individual w it hin t he f amily; t hat is, if it s eff ect is t o enhance diff erences bet w een f amily members. The cat egories of shared and non-shared environment al inf luences are st at ist ical not ions and each cat egory cont ains many unident if ied f act ors t hat are not necessarily specif ically invest igat ed in a quant it at ive research project .

Q U A N TI TATI V E

4.9

4

Environmental influences on variation

CH A PTER

average height of most West ern populat ions increased by 1.0 cm per decade bet w een 1920 and 1970, even t hough t he genes in t hose populat ions could not have changed subst ant ially. In large out bred populat ions, any not iceable change in t he f requency of part icular genes w ill t ake many cent uries. The example is apposit e, because a similar increase in IQ t est scores also occurred t hroughout most of t he t w ent iet h cent ury in most indust rialised count ries. At diff erent t imes and places, t his increase ranged f rom 0.3 t o 10 IQ point s per decade. How ever high t he herit abilit y of IQ might be, and it is cert ainly not as high as 0.90, environment al changes can pot ent ially have a subst ant ial impact .5 It is w ort h not ing t hat any societ y t hat succeeds in reducing diff erences in t he environment s experienced by diff erent members of t hat societ y, f or example, by improving educat ion services in deprived areas, w ill probably increase t he herit abilit y of t heir charact erist ics – in t his case, int elligence.

Gene–environment correlation and interaction 4.11 In most st udies in behavioural genet ics, t he eff ect s of gene–environment correlat ion and gene–environment int eract ion cannot be est imat ed separat ely and are included w it hin t he est imat e of herit abilit y. This means t hat even w hen a t rait is highly herit able, environment al inf luences may st ill be import ant in mediat ing t he eff ect s of t he genes on behaviour. For example, in t he case of gene–environment correlat ion, if exposure t o f riendly company w ere correlat ed w it h a person’s genot ype, sociabilit y could be f ound t o be herit able even t hough it may have arisen as a result of increased exposure t o company.

5

See Chapt er 7.

6

An inf luent ial book arguing t hat parent ing does not mat t er is Harris, J. R. (1998). The Nurt ure Assumpt ion. New York: The Free Press.

7

Rut t er, M . & Silberg, J. (2002). Gene-environment int erplay in relat ion t o emot ional and behavioral dist urbance. An. Rev. Psychol. 53, 463–90.

4 1

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

4.12 Since est imat es of herit abilit y in t radit ional st udies in quant it at ive genet ics might be due not just t o t he direct eff ect of genes, but also t o t he indirect eff ect s of environment al f act ors t hat correlat e w it h genes and t hat have an eff ect cont ingent on genot ype, t hey are likely t o overest imat e t he cont ribut ion of genet ic f act ors t o variat ion. Because of t he complex relat ionship bet w een genet ic and environment al f act ors, it can be diff icult f or st at ist ical approaches t o model t hem accurat ely, meaning t hat t he many complicat ed relat ionships t hat may exist bet w een genet ic and environment al f act ors are of t en over-simplif ied.

Family, tw in and adoption studies 4.13 Family, t w in and adopt ion st udies are used t o examine t he cont ribut ion of genet ic and environment al inf luences on t rait s and disorders. Each of t hese met hods has it s ow n merit s and disadvant ages, but as f or all research, consist ent f indings f rom diff erent t ypes of st udies allow f or great er conf idence in draw ing conclusions.

Family studies 4.14 Family st udies are designed t o examine w het her t he chance of having a part icular charact erist ic is increased in t he relat ives of t hose w ho are have t he charact erist ic, compared t o t he relat ives of t hose w ho do not . An increased incidence in relat ives of aff ect ed individuals indicat es t hat t he t rait is f amilial, t hat is, t hat it appears t o run in f amilies. For cont inuously dist ribut ed charact erist ics, rat her t han calculat ing relat ive risks, researchers est imat e t he similarit y of biological relat ives in f amilies f or t hese t rait s by calculat ing a correlat ion coeff icient . A correlat ion of zero indicat es no similarit y and a posit ive correlat ion indicat es similarit y bet w een relat ives. Tot al similarit y w ould result in a maximum correlat ion of 1. A signif icant posit ive correlat ion suggest s t hat t he t rait is f amilial (but not necessarily genet ic). 4.15 Family st udies of behavioural charact erist ics such as personalit y, IQ t est scores and childhood behaviours have consist ent ly show n t hat f amily members are more similar t o each ot her t han unrelat ed individuals. It is also clear f rom f amily st udies t hat t hese sort s of charact erist ics show a complex pat t ern of inherit ance (such t hat t hey are somet imes t ermed complex t rait s), w hich suggest s t hat t hey are inf luenced by a number of diff erent genes in combinat ion w it h environment al inf luences. That a charact erist ic is common t o f amily members could be due eit her t o genes t hat relat ives share, or t o environment al f act ors t hat impact on all f amily members in a w ay t hat makes t hem more similar. Thus, f indings f rom f amily st udies alone do not provide conclusive evidence of a genet ic cont ribut ion. Tw in and adopt ion st udies allow us t o disent angle, t o some ext ent , t he eff ect s of genes and shared environment al f act ors.

Studies of tw ins M et hods 4.16 M onozygot ic (M Z) t w ins come f rom t he same f ert ilised egg and are genet ically ident ical, t hat is, t hey have 100% of t heir genes in common. Non-ident ical or dizygot ic (DZ) t w ins, like ot her siblings, share, on average, 50% of t heir genes. A great er similarit y or correlat ion bet w een M Z t w ins t han DZ t w ins indicat es a genet ic inf luence. St udies of t w ins allow researchers t o examine w hat proport ion of t he t ot al phenot ypic variance is explained by genet ic f act ors, shared environment al f act ors and non-shared environment al f act ors.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Rut t er, M ., Pickles, A., M urray, R. & Eaves, L. (2001). Test ing hypot heses on specif ic environment al causal eff ect s on behavior. Psychol. Bull. 127, 291–324.

9

There is anot her pot ent ially import ant diff erence in t he prenat al environment s of t w ins. All DZ t w ins, and some M Z t w ins, are surrounded by diff erent sacs or chorions in t he ut erus. But some M Z t w ins are monochorionic: t hey share t he same chorion. If monochorionic M Z t w ins experience a more similar prenat al environment t han dichorionic t w ins, t his might explain w hy M Z t w ins as a group resemble one anot her more closely t han DZ t w ins. The possibilit y is open t o a simple t est : dichorionic M Z t w ins should resemble one anot her less t han monochorionic M Z t w ins, and no more t han DZ t w ins. How ever, st udies t hat have f ocused on t hese diff erent t ypes of t w in do not yet provide conclusive evidence eit her w ay.

H ERI TA BI LI TY

8

M EA SU RI N G

Int erpret at ion of t w in st udy f indings 4.21 St udies involving a large number of pairs of t w ins can be usef ul in providing basic inf ormat ion about w hat sort s of f act ors inf luence variat ion in a t rait , and in ref ining def init ions of charact erist ics. St udies of t w ins are increasingly being used t o assess t he cont ribut ion of environment al f act ors and t o examine t he pat hw ays mediat ing t he eff ect s of environment al f act ors on behavioural t rait s. This t ype of design has also been used t o examine t he overlap of diff erent t rait s (f or example, st udies of t w ins suggest t hat common genet ic f act ors inf luence bot h anxiet y and depressive sympt oms), and in examining t he underlying inf luences on normal variat ion compared w it h ext remes. Caut ion, how ever, is also needed t o avoid over-int erpret ing t he meaning of herit abilit y. There is a considerable lit erat ure discussing t hese concerns and w e highlight t w o key areas:

GEN ETI CS:

4.20 Overall, alt hough t here are crit icisms of t he t w in met hod, t hese are not suff icient t o cast doubt on t he usef ulness of t his st udy design. Nevert heless, t here are clearly good reasons t o use a variet y of research st rat egies in examining t he cont ribut ion of genet ic and environment al inf luences t o behaviour bef ore draw ing conclusions.

Q U A N TI TATI V E

4.19 Despit e t he f act t hat M Z t w ins share t he same genome, t hey are never t ruly ident ical. They diff er in behaviour and physique as w ell as in int ellect ual abilit ies and personalit y t rait s. Some of t hese diff erences w ill be due t o random or chance eff ect s, ot hers due t o environment al inf luences t hat are not shared by t he t w ins. How ever, alt hough t he assumpt ion is made t hat M Z t w ins are genet ically ident ical, t he process of M Z t w inning is complex and it is now know n t hat t here are various biological mechanisms t hat can lead t o genet ic diff erences bet w een t hem.

4

4.18 Anot her crit icism is t hat f indings in t w ins may not be so easily ext rapolat ed t o non-t w ins (singlet ons). Tw ins experience great er int raut erine and perinat al adversit y, and t he experience of being brought up as a t w in is unusual. How ever, t w ins do not appear t o diff er markedly f rom singlet ons f or most t ypes of charact erist ics, ot her t han in show ing delays in t he acquisit ion of language.

CH A PTER

4.17 St udies of t w ins are based on a number of assumpt ions. One is t hat pairs of M Z and DZ t w ins experience very similar environment s. This assumpt ion, called t he equal environment s assumpt ion, has been crit icised. Indeed, t here is evidence t hat M Z t w ins do experience a more similar environment t han DZ t w ins. In most st udies, it is assumed t hat t he equal environment s assumpt ion is correct w hen t he degree t o w hich t w ins share an environment has been measured by quest ionnaire, but t hese measures do not necessarily include t he relevant environment al f act ors. There is increasing evidence t hat many environment al f act ors t hat are relevant f or behaviour are more of t en shared by M Z t w ins t han DZ t w ins.8 St udies of t w ins also ignore t he possible role of prenat al environment . Whet her subsequent ly separat ed or not , t w ins, unlike ot her siblings, have shared t he same prenat al environment at t he same t ime.9

4 3

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

■ St udies of t w ins f ocus on populat ions, not individuals St udies of t w ins have revealed t hat variat ion in many diff erent charact erist ics is herit able. Est imat es of herit abilit y and t he proport ion of variance at t ribut able t o environment al f act ors only ref er t o t he populat ion st udied. Thus, f or example, many st udies of t w ins have used represent at ive t w ins born w it hin a def ined geographical area, in general a sound st rat egy. How ever, f indings w ill ref er t o t he populat ion st udied and may not generalise t o ot her groups, f or example, t o t hose exposed t o severe adversit y or f rom diff erent age and et hnic groups. ■ Ext remes versus normal variat ion In populat ion-based samples of t w ins, most part icipant s do not show ext reme scores. The origins of severe or ext reme behaviours may be dif f erent f rom t hose f or charact erist ics w it hin t he normal range and t hus t he est imat es of herit abilit y and environment al variance obt ained f rom t w in st udy samples may not necessarily apply t o groups of ext remely high or low scorers. How ever, a t ype of st at ist ical analysis know n as ‘ext remes analysis’ 10 allow s f or t he t est ing of w het her t he relat ive cont ribut ion of genes and environment f or ext remely high or ext remely low scores diff ers f rom t hat f or variat ion across t he normal range. For example, it may be t hat genet ic f act ors inf luence normal variat ion in a t rait , but t hat environment al f act ors are more import ant f or ext remes. This t ype of analysis has suggest ed t hat t he magnit ude of genet ic and environment al inf luences on high levels of overact ivit y and inat t ent ion in children appears t o be no diff erent f rom t hat on ‘normal variat ion’ in t hese t ypes of sympt oms.11 How ever, very large sample sizes are needed t o pick up diff erences bet w een normal variat ion and ext remes.

Adoption studies 4.22 Adopt ion st udies involve st udying t he biological and adopt ive relat ives of individuals w ho have been adopt ed. If individuals w ho are genet ically relat ed (biological relat ives) are more similar f or a part icular charact erist ic t han adopt ive relat ives, t his suggest s t hat genet ic f act ors inf luence t hat t rait . If relat ives w ho are genet ically unrelat ed are more similar f or t hat t rait , t his is suggest ive of a cont ribut ion f rom environment al f act ors. Adopt ion st udies provide a pow erf ul means of examining genet ic and environment al inf luences and invest igat ing gene–environment int eract ion. How ever, t w o dif f icult ies w it h such st udies are t hat adopt ees are not placed randomly int o adopt ive f amilies (t hey t end t o be chosen t o provide environment s t hat are low -risk), and adopt ion is an unusual event in it self . 4.23 For t rait s such as int elligence, personalit y and ant isocial behaviour, adopt ion st udies have added t o evidence f rom st udies of t w ins in demonst rat ing a genet ic cont ribut ion t o variat ion. Adopt ion st udies have also demonst rat ed import ant ef f ect s of gene–environment correlat ion. For example, adopt ion st udies have f ound t hat t he adopt ive parent s of children w ho are t hought t o be at increased risk of ant isocial behaviour because t heir biological parent s show similar behavioural t rait s, display

4 4

10

DeFries, J. C. & Fulker, D. W. (1988). M ult iple regression analysis of t w in dat a: et iology of deviant scores versus individual diff erences. Act a Genet . M ed. Gemellol. (Roma) 37, 205–16.

11

St evenson, J. (1992). Evidence f or a genet ic et iology in hyperact ivit y in children. Behav. Genet . 22, 337–44.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

■ Examining w hy t w o t rait s may go hand in hand. This t ype of analysis has show n t hat anxiet y and depression of t en occur t oget her and are inf luenced by t he same set of genes.

H ERI TA BI LI TY

■ Examining how psychosocial/environment al inf luences moderat e genet ic eff ect s. For example, as ment ioned earlier (Box 3.3), st udies of t w ins have show n t hat t he impact of lif e event s on depression varies depending on genet ic suscept ibilit y.

M EA SU RI N G

■ Examining t he cont ribut ion of psychosocial f act ors. For example, examining t o w hat ext ent parent ing f act ors might increase t he risk of behavioural problems, even w hen genet ic inf luences are t aken int o account .

GEN ETI CS:

4.25 Quant it at ive genet ic research is t radit ionally regarded as a w ay of examining w het her or not a part icular disorder or charact erist ic is genet ically inf luenced. Since virt ually every human charact erist ic is genet ically inf luenced t o some ext ent , at t ent ion is t urning t o using quant it at ive research t o answ er ot her quest ions. So w hy do researchers st ill conduct st udies t hat involve est imat es of herit abilit y? The object ive of f amily, t w in and adopt ion st udies is now much broader t han simply examining w het her genes inf luence a part icular t rait . These met hods are now used t o examine a much w ider range of issues t hat are clinically and scient if ically relevant , such as:

Q U A N TI TATI V E

Current uses of quantitative genetic studies

4

4.24 Adopt ion st udies have also show n t hat genes and environment can have an int eract ive inf luence; t hat is t he eff ect s of environment al adversit y are much more marked w hen t here is also genet ic suscept ibilit y. For example, analysis of dat a f rom t hree adopt ion st udies show ed signif icant increased adolescent ant isocial behaviour in adopt ees w hen t hey w ere bot h at increased genet ic risk and t hen exposed t o an adverse environment . This increased risk w as signif icant ly great er t han t he eff ect s of genet ic and environment al f act ors act ing alone.13

CH A PTER

increased negat ive parent ing.12 This is t hought t o provide a demonst rat ion of how an environment al f act or (negat ive parent response) may be inf luenced by t he charact erist ics of t he child and illust rat es t he complexit y of t he relat ionship bet w een genet ic and environment al f act ors.

■ Examining t he relat ionship bet w een sympt oms w it hin t he normal range and ext remes. This t ype of w ork has show n t hat some t rait s (f or example, At t ent ion Def icit Hyperact ivit y Disorder sympt oms) lie along a cont inuum, w it h similar genet ic eff ect s on high scores and on sympt oms w it hin t he normal range. Findings f or ot her t rait s have been diff erent . For example, t he relat ive cont ribut ion of genes and environment t o variat ion in IQ scores appears t o diff er f or very low IQ scores compared t o scores in t he normal range.

12

Ge, X. et al. (1996). The development al int erf ace bet w een nat ure and nurt ure: A mut ual inf luence model of child ant isocial behaviour and parent ing. Dev. Psychol. 32, 574–89; O’Connor, T. G., Deat er-Deckard, K., Fulker, D., Rut t er, M . & Plomin, R. (1998). Genot ype–environment correlat ions in lat e childhood and early adolescence: Ant isocial behavioural problems and coercive parent ing. Dev. Psychol. 34, 970–81.

13

Cadoret , R. J., Cain, C. A. & Crow e, R. R. (1983). Evidence f or gene-environment int eract ion in t he development of adolescent ant isocial behavior. Behav. Genet . 13, 301–10.

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Conclusion 4.26 In summary, f amily, t w in and adopt ion st udy designs each have diff erent st rengt hs and w eaknesses. It is import ant t o recognise t he limit at ions of any t ype of st udy design, t o maint ain a crit ical approach t o int erpret ing f indings and t o avoid over-int erpret at ion (see Box 4.1). Nevert heless, w hen f indings f rom diff erent st udies are consist ent , research in quant it at ive genet ics provides a usef ul met hod f or st udying t he f act ors t hat inf luence diff erent human charact erist ics.

Box 4.1: Central points regarding research in quantitative genetics ■ Quant it at ive genet ics involves st at ist ical met hods t hat at t empt t o dist inguish t he eff ect s of genet ic and environment al f act ors on variat ion in cert ain behavioural t rait s, w hich can be quant it at ively measured, bet w een groups of individuals. ■ The subject s of t he research are usually t w ins, siblings, adopt ed children, and f amilies. ■ The st at ist ics such as est imat es of herit abilit y generat ed by t he research ref er t o groups of people, not t o individuals. Nor do t hey ref er t o part icular genes or regions of DNA or t o specif ic environment al f act ors. This requires f urt her research and addit ional measurement . ■ Estimates of heritability and other statistical techniques are useful in understanding the relative contribution of different types of influence and their relation to each other. They are also useful for understanding why some types of behaviour often occur together. They do not, however, lead directly to predictive information regarding individuals, nor do they give reliable estimates of how strongly predictive a genetic test might be if it were developed.

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Chapter Ident if ying genet ic f act ors cont ribut ing t o individual diff erences in behaviour

5

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Est imat es of herit abilit y (see Chapt er 4) provide evidence t hat genet ic f act ors cont ribut e, t o a great er or lesser ext ent , t o variat ion in behavioural t rait s. A great deal of eff ort is current ly being made t o ident if y t hese f act ors using molecular genet ic approaches. This chapt er review s t hese met hodologies. Research in molecular genet ics is diff erent f rom research in quant it at ive genet ics in t hat it at t empt s t o ident if y t he f unct ion of part icular genes, w hereas research in quant it at ive genet ics examines unspecif ied genet ic inf luences.

5.2

Research f ocused on examining t he genet ic cont ribut ion t o normal variat ion in behavioural t rait s is a branch of neuroscience. It t hus represent s anot her met hod used t o seek underst anding of how t he brain w orks. Research in molecular genet ics can also play a role in psychosocial and epidemiological research, enabling conf ounding genet ic eff ect s t o be ident if ied and cont rolled f or, and t o allow f or f urt her st udy of t he non-genet ic f act ors t hat inf luence a charact erist ic. A f urt her reason f or undert aking research on normal variat ion is t hat it w ill provide inf ormat ion relevant t o disorders and diseases. As already observed, t here may be common genet ic inf luences on behaviour in t he normal range, such as anxiet y, and disorders, such as clinical depression. Furt her, a part icular genet ic inf luence may be linked bot h t o behaviour in t he normal range, as w ell as t o ext remes of t hat behaviour.

Approaches to identifying susceptibility alleles 5.3

At t empt s t o ident if y suscept ibilit y alleles t hat inf luence t rait s represent various blends of ‘bot t om-up’ and ‘t op-dow n’ approaches. The ‘bot t om-up’ approach st art s w it h know ledge of t he biochemist ry of t he syst em in quest ion, and invest igat es, in a logical f ashion, how t he syst em may be varied. Wit h behaviour, t he problem is t hat in most cases, t he biochemist ry is underst ood imperf ect ly, if at all.1

5.4

If t here is some background biochemist ry t o direct researchers, a ‘candidat e gene’ approach can be t aken, by st udying genet ic variat ion t hat is know n t o aff ect t he f unct ion of prot eins suspect ed of having a role in behaviour, f or example, t hose t hat act in t he brain. An example of t his approach is t he dopamine D4 recept or (DRD4), w hich is discussed in paragraphs 5.9 - 5.10.

5.5

The next level of approach is t o ident if y a variat ion in t he relevant gene t hat is speculat ed t o aff ect t he f unct ion of t he prot ein. The best candidat es f or polymorphisms t o st udy are t hose t hat involve amino acid subst it ut ions t hat are chemically signif icant , or are surmised

1

One except ion t o t his st at ement relat es t o alcoholism. Alcohol is rapidly broken dow n in t he body, or met abolised, t o f orm acet aldehyde, a highly t oxic chemical t hat causes nausea, f acial f lushing, dizziness, headaches and ot her unpleasant sympt oms. In most gene pools, individuals possess variant alleles of t he aldehyde dehydrogenase gene t hat enables acet aldehyde t o be easily broken dow n. How ever, t here is a part icular variant allele of t he ALDH gene, common in people f rom Sout h East Asia, t hat leads t o a slow -met abolising f orm of t he prot ein, ALDH2* 2. When t hese individuals (part icularly ALDH 2* 2 homozygot es) drink alcohol, t hey experience t oxic levels of acet aldehyde and t he accompanying sympt oms. Possession of one or t w o slow -ALDH alleles prot ect s against alcoholism. In f act , f rom hundreds of individuals screened, only a single Asian alcoholic w as report ed t o be an ALDH2* 2 homozygot e (Chen, C.-C. et al. (1999). Int eract ion bet w een t he f unct ional polymorphisms of t he alcohol-met abolism genes in prot ect ion against alcoholism. Am. J. Hum. Genet . 65, 795–807). Thus, t his single gene conf ers subst ant ial prot ect ion against alcoholism. This is a rare example of a single gene t hat is conclusively linked t o a behavioural t rait .

I D EN T I FY I N G G EN ET I C FA CT O RS CO N T RI BU T I N G T O I N D I V I D U A L D I FFEREN CES I N BEH A V I O U R

5.1

5

Introduction

CH A PTER

Ident if ying genet ic f act ors cont ribut ing t o individual diff erences in behaviour

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

t o aff ect t he levels of expression of prot eins t hat have a role in brain f unct ion. An indirect w ay t o det ermine an eff ect on f unct ion is t o t ry t o f ind an associat ion bet w een t he prot ein variat ion and behaviour; t hen, if a signif icant associat ion is f ound, t o t ry t o est ablish w hat t he f unct ional eff ect might be. 5.6

Finally, t he most ext reme ‘t op-dow n’ approach (t he hypot hesis-f ree met hod) examines t he relat ionship bet w een genet ic variat ion of unknow n f unct ion (usually in t he f orm of mult iallelic variant s, t ermed microsat ellit es,2 or SNPs) and t he behaviour under st udy. A signif icant associat ion might indicat e one of t hree t hings: (i) t he eff ect s of chance; (ii) t hat t he variat ion serves as a proxy signal f or a nearby variant t hat inf luences t he behaviour t hat occurs t hrough a process t ermed linkage disequilibrium, w hich describes t he t endency f or closely spaced markers t o be inherit ed t oget her, only becoming separat ed by rare recombinat ions; (iii) t hat t he variat ion might it self be inf luencing t he behaviour (f or example, t he variat ion might t urn out t o lie in a region out side a gene, inf luencing t he gene’s expression).

Linkage studies

5 0

5.7

Tw o general met hodologies are used t o f ind or t est f or suscept ibilit y alleles. These are linkage and associat ion st udies. Linkage st udies f ollow t he inherit ance of t rait s t hrough f amilies in comparison w it h polymorphic genet ic markers. The consist ent co-inherit ance of variat ion at a polymorphic locus w it h a t rait w ould support t he hypot hesis t hat t he t rait w as inf luenced, at least in part , by genet ic variat ion close t o t he polymorphism being st udied. Conversely, t he random inherit ance of t he polymorphism and t he t rait w ould be evidence against linkage. Linkage analysis in large f amilies has been very successf ul in t he ident if icat ion of single gene disorders, but is less applicable t o t he st udy of behaviour, w hich does not segregat e in a simple dominant or recessive f ashion.

5.8

Simplif ied t ypes of linkage analysis, f or example, using pairs of aff ect ed siblings, have t he advant age t hat t hey do not assume a part icular mode of inherit ance. Also t hey can bet t er accommodat e variat ion in t he t rait along a cont inuous scale (rat her t han as present /absent cat egories) in a so-called quant it at ive t rait locus (QTL) design. This approach has been used t o map suscept ibilit y alleles f or t rait s (including behaviour) in animals. In humans, relat ively large samples (several hundred pairs of siblings) are required, and even t hese only have t he pow er t o det ect quit e major eff ect sizes.3 Perhaps f or t his reason, linkage st udies have not been applied very w idely t o t he st udy of behaviour. A not able except ion, t hough, is t he early report ed linkage bet w een male homosexualit y and genet ic variat ion in t he Xq28 region of t he X chromosome,4 w hich remains cont roversial (see paragraphs 10.14 – 10.17).

2

M icrosat ellit es cont ain t andem repeat s of a simple sequence such as t he dinucleot ide CA, t hat vary in number and are usually of no f unct ional signif icance. At a part icular locus, one person might have (f or example) 10 CA repeat s on one chromosome and 14 on t he ot her. Anot her person might have 11 and 13 repeat s on t heir t w o chromosomes. Because t hese repeat lengt hs are usually st ably inherit ed f rom generat ion t o generat ion, diff erences in t he dist ribut ion of repeat lengt hs bet w een t w o populat ions may indicat e diff erences in t heir genet ic origins.

3

Risch, N. & M erikangas, K. (1996). The f ut ure of genet ic st udies of complex human diseases. Science 273, 1516–17.

4

Hamer, D. H., Hu, S., M agnuson, V. L., Hu, N. & Pat t at ucci, A. M . (1993). A linkage bet w een DNA markers on t he X chromosome and male sexual orient at ion. Science 261, 321–7.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Association studies

5.10 Tw o highly inf luent ial papers published in 1996 suggest ed t hat a part icular allele of DRD4 w as associat ed w it h novelt y-seeking behaviour.5 How ever, t he eff ect of t he allele w as modest : t he papers concluded t hat t his polymorphism account ed f or only 3–4% of overall variat ion in novelt y-seeking. Nevert heless, t his w ork sparked a deluge of st udies of possible associat ions of DRD4 w it h many aspect s of behaviour, including alcoholism, drug abuse and At t ent ion Def icit Hyperact ivit y Disorder (ADHD). A subsequent crit ique concluded t hat t he associat ions w it h novelt y-seeking t hat w ere originally report ed, as w ell as t hose w it h alcoholism and drug abuse, w ere not st at ist ically robust . How ever, a w eak associat ion might exist bet w een t he 7-repeat allele and ADHD,6 a conclusion also support ed by a recent met a-analysis.7 5.11 A f requent crit icism of associat ion st udies is t hat if t here are subt le, but undet ect ed diff erences in t he populat ions f rom w hich t he cases and mat ched cont rols w ere sampled, t hen diff erences in allele f requency might simply ref lect t he background evolut ionary diff erences bet w een t he t w o samples, rat her t han ref lect ing t rue t rait -specif ic diff erences. This problem is t ermed st rat if icat ion. One w ay t o avoid t his is t o incorporat e parent s or siblings int o t he design and examine diff erences in t he f requency w it h w hich t he t w o parent al alleles are passed dow n t o t he off spring (t ransmission disequilibrium t est s). This approach provides a ‘half w ay house’ bet w een linkage and associat ion.

5

The allele is called t he 7-repeat allele, because it cont ains seven repeat s of a part icular series of 48 base pairs f ound in t he gene. Ot her alleles have been ident if ied t hat cont ain bet w een t w o and eleven repeat s of t his sect ion. Ebst ein, R. P. et al. (1996). Dopamine D4 recept or (D4DR) exon III polymorphism associat ed w it h t he human personalit y t rait of Novelt y-seeking. Nat . Genet . 12, 78–80; Benjamin, J. et al. (1996). Populat ion and f amilial associat ion bet w een t he D4 dopamine recept or gene and measures of Novelt y-seeking. Nat . Genet . 12, 81–4.

6

Pat erson, A. D., Sunohara, G. A. & Kennedy, J. L. (1999). Dopamine D4 recept or gene: novelt y or nonsense? Neuropsychopharmacol. 21, 3–16. The aut hors st at e t hat ‘evidence f or t he role of DRD4 in novelt y-seeking is inconclusive, w it h a number of met hodological concerns’.

7

Faraone, S. V., Doyle, A. E., M ick, E. & Biederman, J. (2001). M et a-analysis of t he associat ion bet w een t he 7-repeat allele of t he dopamine D(4) recept or gene and at t ent ion def icit hyperact ivit y disorder. Am. J. Psychiat ry 158, 1052–7.

I D EN T I FY I N G G EN ET I C FA CT O RS CO N T RI BU T I N G T O I N D I V I D U A L D I FFEREN CES I N BEH A V I O U R

Associat ion st udies are more commonly used f or genet ic st udies of behaviour. In it s simplest f orm, an associat ion st udy compares t he f requency of a part icular genet ic variant in a cohort of cases (a group of people w it h a part icular behavioural charact erist ic) w it h a mat ched set of cont rols (a similar group of people not displaying t he charact erist ic). In t he st udy of behaviour, ‘cases’ as such may not exist , since behavioural t rait s are unlikely t o be easily cat egorised as present or absent ; QTL designs can accommodat e t his. Tw o major advant ages of associat ion over linkage st udies are, f irst , t hat t hey are more pow erf ul f or det ect ing suscept ibilit y alleles of small eff ect size, such as t hose ant icipat ed in genet ic inf luences on behaviour, and second, t hat t he samples are easier t o collect because only single aff ect ed individuals are needed in each f amily. An example of an associat ion st udy is t he occurrence of diff erent genet ic variant s of t he DRD4 gene in novelt y-seeking behaviour. As dopamine is a key neurot ransmit t er, t his DRD4 polymorphism is a plausible candidat e as a cont ribut or t o genet ic variat ion in behaviour.

5

5.9

CH A PTER

How ever, several f urt her linkage st udies are in progress, examining, f or example, anxiet y, depressive sympt oms and neurot icism.

5 1

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

5.12 Anot her major problem w it h associat ion st udies is t hat t he t est ing of very large numbers of loci w ill lead t o numerous spurious associat ions f or purely st at ist ical reasons, using normal crit eria f or signif icance. A common approach t o combat t his eff ect is t o carry out a replicat ion st udy, in w hich pot ent ial associat ions ident if ied in an init ial screen are reexamined in an independent group of individuals. 5.13 In pract ice, t w o approaches have been dominant in t he st udy of behaviour. The f irst are associat ion st udies employing variant s in candidat e genes of eit her know n or pot ent ial f unct ional signif icance. This has been t he most popular approach t o dat e.8 The second is t o use a w hole genome, hypot hesis-f ree approach t o st udy associat ion, in w hich all gene variant s are of int erest , not just select ed candidat es. Research by Plomin et al on t he at t empt ed ident if icat ion of QTLs f or general cognit ive abilit y (g) provides one of t he f irst examples of a f ully hypot hesis-f ree, genomic approach t o t he st udy of a behavioural t rait (see paragraphs 7.15 – 7.24).9 It also illust rat es many of t he diff icult ies w it h t his approach.

Identification of alleles that influence behaviour 5.14 The robust replicat ion of a linkage or associat ion ident if ies a small segment of t he genome t hat cont ains a suscept ibilit y allele, but does not necessarily ident if y t he allele t hat act ually inf luences t he behavioural t rait . This is inevit ably t he case f or linkage, w hich examines gene loci, not specif ic alleles. In t he case of associat ion, t he occurrence of linkage disequilibrium complicat es t he int erpret at ion as t he ident if ied allele might be a neut ral hit ch-hiker w it h anot her (unident if ied) allele close by. The next st ep in a linkage approach is t o reduce t he ext ent of t he chromosomal segment w hich needs t o be examined, by recruit ing addit ional f amilies and t est ing addit ional markers. The DNA sequence of t he def ined int erval is t hen scrut inised f or regions likely t o encode genes; a list of ‘candidat e genes’ is draw n up and t he DNA sequence of each is obt ained, looking f or sequence changes f rom normal. In t he case of associat ion, at t empt s are made t o ident if y all t he SNPs near t he sit e show ing t he init ial associat ion, t hen all t he SNPs are t est ed t o det ermine w het her any show a st ronger associat ion w it h t he t rait t han t he allele originally ident if ied. 5.15 As may be deduced f rom t his abbreviat ed account , t he ident if icat ion of alleles t hat have an inf luence on complex t rait s is by no means st raight f orw ard, even w hen a robust linkage or associat ion can be ident if ied. Whereas in research involving animals t his process is f acilit at ed by t he use of specif ic breeding st rat egies, t his is clearly impossible in humans. M oreover, in cont rast t o M endelian t rait s, it is unlikely t hat any specif ic allele w ill be bot h necessary and suff icient t o cause t he t rait , so t he genet ic evidence f or causat ion w ill be of a st at ist ical nat ure. Furt her evidence of a causal link must be sought t hrough f unct ional st udies. M ost of t en t hese w ill involve experiment s on animals, discussed in Chapt er 6.

Scaling up the analysis: new methods in genetics 5.16 The past few years have witnessed the move of genetics from small-scale science conducted in individual laboratories to a larger-scale approach similar to that employed for many years in substantial physics projects as well as in industry. This has been prompted by various factors, including the availability of the sequence of the human genome, the development of partially

5 2

8

An example is provided by t he w ork of Comings, D. E. et al. (2000). A mult ivariat e analysis of 59 candidat e genes in personalit y t rait s: t he t emperament and charact er invent ory. Clin. Genet . 58, 375–85.

9

Plomin, R. et al. (2001). A genome-w ide scan of 1842 DNA markers f or allelic associat ions w it h general cognit ive abilit y: a f ive-st age design using DNA pooling and ext reme select ed groups. Behav. Genet . 31, 497–509.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

5.18 It is likely t hat t here w ill be a signif icant increase in t he applicat ion of molecular genet ics t o t he st udy of behaviour. It can be ant icipat ed t hat very large amount s of dat a about t he f unct ion of part icular genes w ill be generat ed over t he coming years, and many claims w ill be made about t he signif icance of t hese dat a. Box 5.1 cont ains a number of point s t hat should be borne in mind w hen evaluat ing such claims.

Box 5.1: Central points about research in molecular genetics ■ Research in molecular genet ics t ries t o ident if y variat ion in part icular genes t hat inf luences behaviour, by examining t he DNA of individuals. ■ This is diff icult because t here are usually many genes involved, each of w hich may only have a small eff ect . M any associat ions bet w een a genet ic variant and a behavioural t rait have been report ed but have not been successf ully repeat ed by ot her researchers. ■ In most cases, t he research does not explain how t he gene inf luences t he behaviour. How ever, some researchers predict t hat t hey w ill overcome t hese diff icult ies and t hat genes t hat inf luence behaviour w ill be reliably ident if ied. ■ When associat ions are report ed by researchers, it is import ant t o consider t he f ollow ing quest ions: - How convincing is t he evidence, in t erms of bot h st at ist ical analysis and t he supposed pat hw ay of causat ion, t hat t he claim is correct ? M uch more credibilit y can be at t ached t o f indings t hat have been independent ly replicat ed by a diff erent research group, and f irst report s of gene–behaviour associat ions should be t reat ed w it h caut ion unt il t hey are replicat ed. - Over w hat range of populat ions and environment al condit ions has t he eff ect been t est ed? - If claims are made about t he pract ical applicat ion of t he f indings t o inf luence human behaviour, w hat is t he size of t he eff ect of t he genet ic variant ? Is it large enough t o have any relevance f or t he t est ing of individuals? - What are t he implicat ions f or t he pat hw ay of causat ion of t he behaviour?

I D EN T I FY I N G G EN ET I C FA CT O RS CO N T RI BU T I N G T O I N D I V I D U A L D I FFEREN CES I N BEH A V I O U R

Conclusion

5

5.17 Apart from the use of rapid methods of analysing genotypes involving large numbers of samples (essential for the approaches outlined above), another technology that promises to yield significant insights is the use of gene chips or microarrays. The best validated application of this technology is for simultaneous examination of the expression of thousands of different genes from a particular source of tissue. DNA sequences from these genes are arrayed onto a glass slide or synthesised chip, then RNA (the intermediate between DNA and protein) from the tissue of interest is prepared and matched by hybridisation to the array. This enables widespread changes in gene expression to be examined. Such methods are likely to come into widespread use in behavioural genetics. It is anticipated that they will lead to a more sophisticated view both of the biology of behavioural processes and to new ways of classifying these processes. Large-scale proteomics approaches, which examine changes in protein, rather than RNA, expression, are also being developed.

CH A PTER

automated high-throughput technologies for analysing DNA sequence and its variation, and the strategic move of the pharmaceutical industry into genetics, as well as the sheer complexity of human genetic variation. It can be anticipated that this trend will continue apace.

5 3

Chapter Research in behavioural genet ics involving animals

6

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Dobkin, C. et al. (1997). FM R1 knockout mouse has a dist inct ive st rain-specif ic learning impairment . Neurosci. 100, 423–9; Fisch, G. S., Hao, H. K., Bakker, C. & Oost ra, B. A. (1999). Learning and memory in t he FM R1 knockout mouse. Am. J. M ed. Genet . 84, 277–82; Tang, Y. et al. (1999). Genet ic enhancement of learning and memory in mice. Nat ure 401, 63–9.

2

Tang, Y. et al. (1999). Genet ic enhancement of learning and memory in mice. Nat ure 401, 63–9; Dulaw a, S. C., Grandy, D. K., Low, M . J., Paulus, M . P. & Geyer, M . A. (1999). Dopamine D4 recept or-knock-out mice exhibit reduced explorat ion of novel st imuli. J. Neurosci. 19, 9550–6.

3

König, M . et al. (1996). Pain responses, anxiet y and aggression in mice def icient in pre-proenkephalin. Nat ure 383, 535–8; Smit h, G. W. et al. (1998). Cort icot ropin releasing f act or recept or 1-def icient mice display decreased anxiet y, impaired st ress response, and aberrant neuroendocrine development . Neuron 20, 1093–102.

4

Cardinal, R. N. et al. (2001). Impulsive choice induced in rat s by lesions of t he nucleus accumbens core. Science 292, 2499–501.

5

De Felipe, C. et al. (1998). Alt ered nocicept ion, analgesia and aggression in mice lacking t he recept or f or subst ance P. Nat ure 392, 394–7; DeVries, A. C., Young, W. S. III & Nelson, R. J. (1997). Reduced aggressive behaviour in mice w it h t arget ed disrupt ion of t he oxyt ocin gene. J. Neuroendocrinol. 9, 363–8; Ledent , C. et al. (1997). Aggressiveness, hypoalgesia and high blood pressure in mice lacking t he adenosine A2a recept or. Nat ure 388, 674–8.

6

Accili, D. et al. (1996). A t arget ed mut at ion of t he D3 dopamine recept or gene is associat ed w it h hyperact ivit y in mice. Proc. Nat l. Acad. Sci. USA 93, 1945–9.

7

Crabbe, J. C. (1996). Elevat ed alcohol consumpt ion in null mut ant mice lacking 5-HT1B serot onin recept ors. Nat . Genet . 14, 98–101; Ledent , C. et al. (1999). Unresponsiveness t o cannabinoids and reduced addict ive eff ect s of opiat es in CB1 recept or knockout mice. Science 283, 401–4; M aldonado, R. et al. (1997). Absence of opiat e rew arding eff ect s in mice lacking dopamine D2 recept ors. Nat ure 388, 586–9; M cBride, W.J. & Li, T.K. (1998). Animal models of alcoholism: neurobiology of high alcohol-drinking behaviour in rodent s. Crit . Rev. Neurobiol. 12, 339–69; Nest ler, E. J. (2000). Genes and addict ion. Nat . Genet . 26, 277–81; Rocha, B.A. et al. (1998). Increased vulnerabilit y t o cocaine in mice lacking t he serot onin-1B recept or. Nat ure 393, 175–8.

8

Ferguson, J. N. et al. (2000). Social amnesia in mice lacking t he oxyt ocin gene. Nat . Genet . 25, 284–8; Gendreau, P. L., Pet it t o, J. M ., Pet rova, A., Gariepy, J. & Lew is, M . H. (2000). D(3) and D(2) dopamine recept or agonist s diff erent ially modulat e isolat ion-induced social-emot ional react ivit y in mice. Behav. Brain Res. 114, 107–17; Lijam, N. et al. (1997). Social int eract ion and sensorimot or gat ing abnormalit ies in mice lacking Dvl1. Cell 90, 895–905.

9

M cGraw, K. J. & Hill, G. E. (1999). Induced homosexual behaviour in male house f inches (Carpodacus maxicanus): t he ‘prisoner eff ect ’. Et hol. Ecol. Evol. 11, 197–201.

10

Flint , J. et al. (1995). A simple genet ic basis f or a complex psychological t rait in laborat ory mice. Science 269, 1432–5.

11

Flint , J. et al. (1995). A simple genet ic basis f or a complex psychological t rait in laborat ory mice. Science 269, 1432–5.

A NIM A LS

1

GEN ETI CS I N V O LV I N G

This chapt er set s out various t ypes of model t hat researchers use and point s t o possible advant ages and problems w it h t he use of animal models t hat should be borne in mind w hen evaluat ing t he result s of such research. The chapt er f ocuses predominant ly on research involving mice, since much research in behavioural genet ics uses mouse models of human behaviour. Alt hough primat es are much closer t o humans in t erms of t heir behaviour, t here are various reasons w hy non-human primat es have not been used as of t en t o st udy t he genet ics of human behaviour. Research involving primat es t ends t o pose

BEH A V I O U RA L

6.2

IN

One met hod of invest igat ing human behaviour is t o examine similar t rait s in animals. Alt hough t hey have obvious limit at ions, animal ‘models’ of human behaviour have f requent ly been an eff ect ive t ool f or scient ist s. Such models are usef ul in underst anding disease, but can also be inf ormat ive about t he cont ribut ion of genet ic f act ors t o some normal behavioural t rait s. M any species are used in bot h genet ic and psychological research int o behaviour, including primat es, mice, rat s, birds, f ish and f ruit f lies. The diff erent t rait s being st udied in t hese animals include: int elligence/learning,1 novelt y seeking,2 anxiet y,3 impulsivit y,4 aggression,5 hyperact ivit y,6 addict ion,7 social int eract ion,8 sexual orient at ion,9 emot ionalit y,10 depression and neurot icism.11

RESEA RCH

6.1

6

Introduction

CH A PTER

Research in behavioural genet ics involving animals

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great er et hical problems t han animal models using rodent s.12 M onkeys do not breed rapidly nor do t hey have large numbers of off spring. The t ime and cost s involved in producing and rearing t hem w ould be prohibit ive. M any st rains of mice already exist t hat have been bred select ively t o display part icular t rait s. For t hese reasons, t he mouse current ly remains t he most commonly used organism f or st udying t he genet ics of human behaviour. 6.3

M any genes involved in f undament al biological processes have been conserved as species have evolved. In ot her w ords, many genes are similar in diff erent species. Due t o t he f act t hat many genes t hat play an import ant role in development and t he prot eins t hey produce t end t o be very similar in mice and humans, considerable evidence has been gat hered f rom research involving mice as a guide t o t he human case. How ever, w hen considering t he f indings of various st udies, it is vit al t o remember t hat conservat ion of a gene across t he t w o species does not necessarily mean t hat t he gene it self , t he t iming of it s expression in t he organism or it s f unct ion w ill be exact ly equivalent in mice and humans.13

How are animal models created? 6.4

Bef ore it became possible t o manipulat e specif ic genes in animals, researchers examined t he eff ect on behaviour of prevent ing part icular part s of an animal’s brain f rom inf luencing it s behaviour in t he normal w ay. Today, changes in an animal’s genet ic make-up can be produced in several w ays, eit her by select ing animals w hich show nat ural variat ion or by inducing variat ion t hrough genet ic manipulat ion.14 The main met hods are: ■ variat ion induced in individual animals by surgery, condit ioning, diet and so on, w hich is not due t o t he animals’ genot ype; ■ select ive breeding (i) of nat urally-occurring t rait s, w here animals are specif ically chosen f or mat ing based on an observed behavioural t rait ; and (ii) of animals exposed t o pre- or post -nat al rearing environment s w hich are eit her enriched or impoverished; ■ variat ion induced in specif ic genes by (i) t he delet ion or ‘knocking out ’ of a gene; (ii) t he under- or over-expression of a gene; (iii) t ransf erring a gene t o creat e a t ransgenic animal; (iv) exposure t o radiat ion or drugs. Variat ion can be as subt le as changing just one base pair; t his somet imes has eff ect s as prof ound as t hose of knocking out t he w hole gene.

6.5

5 8

Select ive breeding capit alises on t he genet ic variat ion t hat is present eit her in unmodif ied mice or in t hose w hich have been produced by cross-breeding t w o or more inbred st rains. M easurement s of behavioural t rait s may be used t o divide groups of animals w hich do not have similar genot ypes int o sub-groups w it h, f or example, high or low aggression, or high or low levels of explorat ory act ivit y. Select ive breeding f rom animals w it h t he most ext reme manif est at ions of t he t rait in quest ion is t hen undert aken f or a number of generat ions.

12

Some of t hese issues w ere discussed in Animal t o human t ransplant s: t he et hics of xenot ransplant at ion, Nuff ield Council on Bioet hics (1996). The issue of t he et hics of research involving animals is out side t he scope of t his Report , but w ill be t he subject of a f ut ure Report by t he Council.

13

Fougerousse, F. et al. (2000). Human–mouse diff erences in t he embryonic expression pat t erns of development cont rol genes and disease genes. Hum. M ol. Genet . 9, 165–73.

14

See f or example Flint , J. (1996). Annot at ion: behavioural phenot ypes: a w indow on t he biology of behaviour. J. Child Psychol. Psyc. 37, 355–67; Heint z, N. (2000). Analysis of mammalian cent ral nervous syst em gene expression and f unct ion using bact erial art if icial chromosome-mediat ed t ransgenesis. Hum. M ol. Genet . 9, 937–43; Hunt er, A. J., Nolan, P. M . & Brow n, S. D. M . (2000). Tow ards new models of disease and physiology in t he neurosciences: t he role of induced and nat urally occurring mut at ions. Hum. M ol. Genet . 9, 893–900; Kempermann, G., Georg Kuhn, H. & Gage, F. H. (1997). M ore hippocampal neurons in adult mice living in an enriched environment . Nat ure 386, 493–5.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

GEN ETI CS I N V O LV I N G A NIM A LS

The mice w ere genet ically alt ered so t hat t hey over-expressed a gene t hat has an eff ect in t he brain and is t hought t o be involved in learning. The modif ied mice w ere t hen compared t o unmodif ied mice in various t asks. These t est ed t he abilit y of t he mice t o recognise object s t hey had previously seen, t o remember event s t hat had caused an emot ional response, t o learn relat ionships bet w een an elect ric shock and a part icular out come and t o succeed in spat ial learning. The genet ically modif ied mice w ere normal in all respect s, except f or learning and memory. They show ed normal grow t h, normal body w eight and normal mat ing behaviour, but appeared t o have enhanced learning capacit y. When t est ed t hree t o six mont hs af t er birt h, t he genet ically modif ied mice show ed a great er t endency f or explorat ory behaviour, a st ronger pref erence f or novel sit uat ions and superior abilit ies t o code and st ore inf ormat ion. The researchers concluded t hat over-expression of t he gene result ed in a bet t er long-t erm memory. How ever, it is very diff icult t o measure t he precise eff ect s of t he overexpression of t he gene in t he brain. M oreover, t he enhancement eff ect s in one experiment last ed only t hree days, and in ot hers f or merely a f ew hours, so t he claims should be t reat ed w it h great caut ion.

BEH A V I O U RA L

Here, w e provide a brief descript ion of a much-publicised research project invest igat ed memory and learning in genet ically modif ied mice.* The st udy w as undert aken t o invest igat e a pot ent ial t reat ment f or t he memory and learning problems of pat ient s w it h Alzheimer’s disease, but it s ext rapolat ion t o t he enhancement of normal variat ion in t hese t rait s, w hich are component s of int elligence, w as f ocused on bot h by scient ist s and t he popular press. The genet ically modif ied mice w ere nicknamed ‘Doogie’ af t er t he int ellect ually precocious st ar of a popular TV programme, Doogie How ser M D.

IN

Box 6.1: The ‘Doogie mice’

RESEA RCH

M ut at ions can be induced at random in t he genome t hrough irradiat ion using X-rays, or by t he use of mut agenic chemicals. Several large-scale project s are under w ay, in w hich t housands of mice are exposed t o mut agenic chemicals. Their off spring are t hen screened f or a w ide range of charact erist ics, including behavioural and neurobiological abnormalit ies. Af t er f inding such mut ant s, t hey can be bred t o creat e a line of animals w it h t he charact erist ics in quest ion. M ut agenesis is of relevance w hen it produces animals t hat have abnormal phenot ypes similar t o complex t rait s of int erest t o t he invest igat or (f or example, increased anxiet y). Once such a mut ant line is est ablished, f urt her research may be able t o ident if y t he mut at ion t hat causes t he t rait . It is not yet clear how f requent ly complex t rait s can be mimicked by induced mut at ions, nor how usef ul such experiment s w ill be in uncovering t he genet ic basis of t he complex t rait it self .

6

6.6

CH A PTER

Of t en, by t he end of a select ion experiment , animals may have become inbred. Groups of animals t hat have similar genot ypes but t hat diff er in t erms of a part icular phenot ype can also be creat ed by inbreeding animals t hat have lit t le genet ic ancest ry in common. These are pow erf ul met hods f or ident if ying genet ic diff erences bet w een st rains; how ever, t he genet ic diversit y t hat is present is limit ed, compared t o t hat w hich occurs nat urally, as a result of using inbred mice.

Nevert heless, t he scient if ic and popular press w as rapid in hailing t hese result s as point ing t o t he exist ence of a ‘gene f or learning’, a ‘gene f or int elligence’ or even simply ‘t he IQ gene’ † t hat might subsequent ly be enhanced in humans. Even t he original press release, issued by Princet on Universit y, t o w hich t he researchers w ere aff iliat ed, claimed t hat ‘t he f inding also

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show s t hat genet ic improvement of int elligence and memory in mammals is now f easible, t hus off ering a st riking example of how genet ic t echnology may aff ect mankind and societ y in t he next cent ury’. This w as based on t he hypot hesis t hat overexpression of t he gene might help t he brain t o ret ain t he ext ensive capacit y f or learning t hat young children possess nat urally early on but gradually lose w it h age. This example at t ract ed media coverage of increasing exaggerat ion t hroughout t he w orld and point s t o t he risks of generalising t he t ent at ive result s of a relat ively rest rict ed experiment on mice t o t he human case. M ore recent experiment s on t he same st rain of genet ically modif ied mice have suggest ed t hat t here is an addit ional, unint ended eff ect of t his manipulat ion, namely an increased suscept ibilit y t o persist ent pain. This illust rat es t hat at t empt s at genet ic enhancement may have unexpect ed side eff ect s.‡

*

Tang, Y. et al. (1999). Genet ic enhancement of learning and memory in mice. Nat ure 401, 63–9.

†

See, f or example, Lemonick, M . D. (1999). Smart Genes? Time M agazine 13 Sept .

‡

Wei, F. et al. (2001). Genetic enhancement of inflammatory pain by forebrain NR2B overexpression. Nat. Neurosci. 4, 164–9.

What are the benefits of using animals to study the genetics of human behaviour? 6.7

One of t he obvious advant ages of research involving mice is t hat t he human and mouse genomes are very similar, so t hat many human genes have count erpart s in mice. M ice breed very rapidly and plent if ully, so programmes of breeding can be more easily implement ed. M any organs in mice are also very similar t o t hose in humans. Thus, discovering t he part s of t he body and brain in w hich a know n or candidat e gene is expressed (called expression analysis) can be done in t he laborat ory w it h a reasonable expect at ion t hat t his w ill usually be similar in t he human case. A part icular advant age is t hat scient ist s can st udy gene expression t hroughout t he development of t he mouse bef ore birt h and in early post nat al lif e, w hich makes it possible t o chart w here and w hen genes are expressed. Some genes are expressed early in development and never again, w hereas ot hers are expressed lat er. The earlier in development t hat a gene is expressed, t he great er t he abilit y t o underst and it s f unct ion. This may enable t he planning of t imely int ervent ion during periods at w hich t he brain is most recept ive t o alt erat ion. New t reat ment s can be t ried out w hen t he f unct ion of genes and t heir product s are f ully ident if ied. For example, using mouse models in w hich genes relat ed t o t he human hearing syst em have been knocked out , researchers may be able t o est ablish t he best period of t ime f or insert ing cochlear implant s.

6.8

Fairly complex behaviours in mammals can be dependent on t he presence and f unct ioning of t he chemicals produced by specif ic genes. For example, st udies in prairie voles have suggest ed t hat t w o chemicals in t he brain, t he neuropept ides oxyt ocin and vasopressin, ‘play import ant roles in behaviours associat ed w it h monogamy, including aff iliat ion, pat ernal care and pair bonding’.15 Some prairie vole species are monogamous. They have been show n t o have a higher densit y of oxyt ocin recept ors in specif ic part s of t he brain t han do closely relat ed non-monogamous species. The specif ic behaviours relat ed t o t he

15

6 0

Young, L. J., Lim, M . M ., Gingrich, B. & Insel, T. R. (2001). Cellular mechanisms of social at t achment . Horm. Behav. 40, 133–8.

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Overeem, S., M ignot , E., Gert van Dijk, J. & Lammers, G. J. (2001). Narcolepsy: clinical f eat ures, new pat hophysiologic insight s, and f ut ure perspect ives. J. Clin. Neurophysiol. 18, 78–105.

18

Fougerousse, F. et al. (2000). Human–mouse diff erences in t he embryonic expression pat t erns of development cont rol genes and disease genes. Hum. M ol. Genet . 9, 165–73.

19

Doyle, J. L., DeSilva, U., M iller, W. & Green, E. D. (2000). Divergent human and mouse ort hologs of a novel gene (WBSCR15/Wbscr15) reside w it hin t he genomic int erval commonly delet ed in Williams syndrome. Cyt ogenet . Cell Genet . 90, 285–90.

20

Keverne, E. B. (1997). An evaluat ion of w hat t he mouse knockout experiment s are t elling us about mammalian behaviour. BioEssays 19, 1091–8.

21

Crabbe, J. C., Wahlst en, D. & Dudek, B. C. (1999). Genet ics of mouse behaviour. Science 284, 1670–2.

A NIM A LS

Insel, T. R. (1997). A neurobiological basis of social at t achment . Am. J. Psychiat . 154, 726–35.

GEN ETI CS I N V O LV I N G

16 17

BEH A V I O U RA L

6.10 In scient if ic experiment s, caut ion should alw ays be exercised in int erpret ing t he result s. Unless replicat ed, report ed f indings cannot be t aken at f ace value, because somet imes out comes diff er even in ost ensibly ident ical condit ions. For example, one group of researchers set up a comparison of result s f rom t hree diff erent laborat ories t hat st udied genet ically modif ied mice in w hich t he gene involved in regulat ing a chemical in t he brain (a neurot ransmit t er called serot onin), had been knocked out .21 Each of t he t hree laborat ories had ident ical st rains of mice and conduct ed t he experiment s st art ing at exact ly t he same t ime, on t he same day and under t he same laborat ory condit ions, using t he same mouse f eed and t he same behavioural t est s. The result s w ere, in some respect s, surprising. For example, in a simple t est of anxiet y (a maze in w hich animals could eit her st ay ‘saf e’, relat ively hidden in areas w it h high w alls, or else vent ure out int o ‘more dangerous’ open areas), t he diff erences bet w een genet ically modif ied mice and t he cont rols, varied as a

IN

While human genes have many homologues in mice, t heir pat t erns of expression are of t en dissimilar bot h spat ially and t emporally.18 Indeed, t ime-dependent processes dif f er signif icant ly bet w een t he t w o species.19 Alt hough specif ic genes may be similar, int eract ions bet w een genes, as w ell as w it h t he int ernal and ext ernal environment s, may be diff erent . Ident ical genes may have diff erent f unct ions w it hin t he development of t he brain in diff erent species and may be expressed at varying t imes and at diff erent development al st ages. It may be t hat haploinsuff iciency (having one inst ead of t he normal t w o copies of a gene) in mice t urns out t o be less det riment al t han in humans. Such pot ent ial diff erences must alw ays be t aken int o account .20 Generalisat ions f rom mouse t o human can somet imes, t heref ore, be premat ure and need t o be examined w it h caut ion.

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6.9

6

What are the problems w ith using animals to study the genetics of human behaviour?

CH A PTER

development of social bonds, but not ot her general behaviours, appear t o be alt ered w hen animals are t reat ed by inject ion of subst ances t hat block t he binding of t hese neuropept ides t o t he relevant cells in t he brain.16 What is much less clear, current ly, is t he ext ent t o w hich similar mechanisms may or may not exert some inf luence on human behaviour, even w it h regard t o disease, let alone w it hin t he normal range. It is import ant t o emphasise t hat t he absence of current evidence of t his nat ure is not evidence t hat such eff ect s could not exist . On t he cont rary, if animal evidence suggest s a neurobiological mechanism underlying cert ain complex behaviours, it is ent irely plausible t hat at least some residue of t hese mechanisms w ill event ually also be discovered in human beings. For example, t he sleep disorder narcolepsy has been f ound t o have t he same chemical basis in mice, dogs and humans.17

6 1

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f unct ion of t he laborat ory. One laborat ory’s modif ied mice show ed more act ivit y in t he open areas of t he maze, t he second laborat ory’s modif ied mice show ed less, and in t he t hird laborat ory t here w as no diff erence in act ivit y bet w een t he modif ied mice and t he cont rols. These result s presumably result f rom uncont rolled diff erences, f or example in handling, in t he odour of t he handlers or in t he composit ion of t he w at er supplied t o t he mice. Some of t hese kinds of diff erences, part icularly handling, might w ell be expect ed t o aff ect t he emot ional responses of t he mice and hence change t heir behaviour in t his simple anxiet y t est . Result s t hat have been replicat ed under diff erent condit ions or using several diff erent w ays of assessing anxiet y are t heref ore likely t o be more reliable t han t hose result ing f rom a single measurement .22 Of course t his caveat does not just apply t o genet ic st udies. The result s obt ained are alw ays likely t o depend in part on t he environment in w hich t he t est is conduct ed. Not e also t hat knocking out a gene t hat is expressed in t he brain, f or example, might have no consequences of behaviour in mice, w hile damage t o t he equivalent genes might by cont rast crit ically aff ect behaviour in t he human case. This is because t he eff ect s of t he expression of t he same gene across t w o species may diff er. 6.11 Genet ic eff ect s are usually very dependent on cont ext (bot h in t erms of ot her genes and of environment al f act ors), such t hat even af t er breeding f or a specif ic behavioural change, it may be signif icant ly alt ered by subsequent experience. In sum, environment al f act ors clearly int eract w it h an animal’s genot ype t o produce t he f inal phenot ype. Furt hermore, genet ic eff ect s can be benef icial in one environment , but damaging in anot her. For example, in t he f ruit f ly, a number of sit es on part icular chromosomes (QTLs) have been ident if ied t hat cont ribut e t o variat ions in lif espan. How ever, research has revealed t hat t he eff ect s of t hese QTLs vary as a f unct ion of sex and of larval environment . Some even have ant agonist ic eff ect s on lif e span in t he diff erent sexes and across diff erent environment s.23 6.12 Anot her f act or relevant t o t he problems of generalising f rom mouse t o human is t he f act t hat t he mouse repert oire of behaviour measurable in t he laborat ory is comparat ively limit ed. Of t en t he eff ect s of genet ically modif ying an animal are only st udied w it h respect t o a single hypot hesis about t he f unct ion of t he gene in quest ion, despit e t he f act t hat t he gene may be pleiot ropic (t hat is, have more t han one eff ect ) and be expressed in several part s of t he body and brain. 6.13 When invest igat ing int elligence in mice, most researchers f ocus on spat ial memory in a t ask called t he w at er maze, in w hich t he mice have t o remember w here a submerged plat f orm is locat ed in a t ank of w at er. How comparable is t he enhancement of t he mouse’s learning capacit y and t hus perf ormance in t he w at er maze t ask (w hich is by no means a nat ural environment f or mice) t o improvement s in, say, human memory in all it s mult iple f orms? Ot her measurement s less of t en used, but perhaps more analogous t o human behaviour, might be speed of processing or t he t ime one t akes t o react t o a novel st imulus.24 Researchers are now t ending t o use a w ider range of t est s in comparing mice t o humans.

6 2

22

For example, Turri, M . G., Henderson, N. D., DeFries, J. C. & Flint , J. (2001). Quant it at ive t rait locus mapping in laborat ory mice derived f rom a replicat ed select ion experiment f or open-f ield act ivit y. Genet ics 158, 1217–61.

23

Leips, J. & M ackay, T. F. C. (2000). Quant it at ive t rait loci f or lif e span in Drosophila melanogast er: int eract ions w it h genet ic background and larval densit y. Genet ics 155, 1773–88.

24

It is import ant t o not e t hat alt hough mouse models have been used t o make claims about enhanced perf ormance, f ast er is not alw ays bet t er in t he human case. One might , f or inst ance, be able t o speed up a mouse’s search f or hidden object s by alt ering one of it s genes. Should it t heref ore be concluded t hat such enhancement w ould be benef icial in t he human case? Not necessarily. People w it h aut ism, f or inst ance, are signif icant ly f ast er t han mat ched cont rols on a visual search t ask (O'Riordan, M . A., Plaist ed, K. C. & Baron-Cohen, S. (2001). Superior visual search in aut ism. J. Exp. Psychol. Hum. Percept . Perf orm. 27, 719–30), but t his enhanced speed is act ually det riment al t o cognit ion and cont ribut es t o t he t endency of people w it h aut ism t o f ocus on specif ic f eat ures at t he expense of cont ext and overall conf igurat ion.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Conclusion

■ It is diff icult t o equat e direct ly t he richness of complex human t rait s such as int elligence, personalit y and sexual orient at ion w it h t he behaviour of animals. This may limit t he pot ent ial value of t he research. ■ For t hese reasons, caut ion should be exert ed w hen hypot hesising t hat genes st udied in research involving animals w ill have t he same eff ect in humans.

GEN ETI CS I N V O LV I N G

■ Alt hough t here are many similarit ies w it h regard t o genet ics bet w een human and nonhuman animals, t here are also considerable diff erences in t he expression of t heir genes bot h w it hin t he organism and over t ime.

BEH A V I O U RA L

■ Animal models can be creat ed by various t echniques including select ive breeding and t he direct manipulat ion of specif ic genes.

IN

■ Animal models have great ly advanced our underst anding of how genes have an eff ect in t he organism and of how t he brain develops.

RESEA RCH

Box 6.2: Central points about animal models of human behaviour

6

6.14 In conclusion, w e have seen t hat research involving animals is one met hod of invest igat ing inf luences on behaviour. While t here are many similarit ies, in t erms of genet ics, bet w een some animals and humans, t he result s of st udies involving animals cannot be t aken t o apply in a st raight f orw ard w ay t o human behaviour. Box 6.2 summarises t he cent ral t hemes t hat have emerged in t his chapt er.

CH A PTER

Indeed, it is becoming increasingly clear t hat good genet ic research requires one t o def ine and measure t he t rait s under st udy eff ect ively.

A NIM A LS 6 3

Section Review s of t he evidence

3

Chapter Review of t he evidence: int elligence

7

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

1

Background 7.1

TH E EV I D EN CE: I N TELLI GEN CE

Psychologist s measure int elligence using a range of t est s called IQ (Int elligence Quot ient ) t est s. How ever, t here is considerable disagreement about w het her t hese t est s do in f act measure int elligence, and even w het her int elligence can be measured by a t est at all. M any crit ics have suggest ed t hat int elligence is t oo complex t o be measured by such t est s:

O F

7.2

REV I EW

Trait definition and measurement

7

The f irst t est s t hat aimed t o measure int elligence w ere developed at t he st art of t he t w ent iet h cent ury. The Simon–Binet t est w as commissioned by t he French government t o ident if y children w ho w ould not benef it f rom ordinary schooling because of low int elligence. It w as subsequent ly adapt ed by researchers in t he US t o measure average and above-average int elligence as w ell. Ot her t est s have been developed in diff erent cont ext s t han educat ion, f or example in milit ary recruit ment . The use of such t est s has of t en aroused cont roversy and crit icism, part icularly w hen combined w it h claims about t he biological basis of variat ion in t est scores. There have been several prominent examples of claims t hat diff erences in IQ bet w een racial groups are due t o genet ic f act ors rat her t han social or environment al ones and, f urt her, t hat t his ought t o inf orm social policy. While it is of t en claimed t hat on average, black individuals score slight ly low er on IQ t est s t han w hit e individuals, w ho in t urn score low er t han people f rom East Asia, t here are also st udies w hich show t hat , if black individuals and w hit e individuals are closely mat ched on socioeconomic st at us, t he diff erences in IQ are subst ant ially reduced.2 The pot ent ial abuse of inf ormat ion about genet ic inf luences on behaviour is discussed f urt her in Chapt ers 1315. Here, it suff ices t o observe t hat research int o genet ic inf luences on int elligence has been associat ed, hist orically, w it h signif icant concerns about misuse of t he inf ormat ion and unf air discriminat ion.

CH A PTER

Review of t he evidence: int elligence

‘IQ psychologist s … like t o t hink t hat int elligence can be measured as if it w ere … a simple scalar quant it y … Unf ort unat ely f or IQ psychologist s t his is not so … Int elligence … is a complicat ed and many-sided business. Among it s element s are speed and span of grasp, t he abilit y t o see implicat ions and conversely t o discern a non sequit ur and ot her f allacies, t o discern analogies and f ormal parallels bet w een out w ardly dissimilar phenomena or t hought st ruct ures, and much else besides. One number w ill not do f or all t hese.’ 3 7.3

How ever, IQ t est s come in a variet y of f orms. Some require an individual t o engage in reasoning in order t o solve novel problems, w hich may be present ed in verbal, numerical or diagrammat ical f orm. Ot hers t est general know ledge or t he ext ent of an individual’s

1

The mat erial in t his chapt er is t aken f rom a paper commissioned by t he Nuff ield Council on Bioet hics f rom Prof essor N. J. M ackint osh, Depart ment of Experiment al Psychology, Universit y of Cambridge. The paper is available on t he Council’s w ebsit e: w w w.nuff ieldbioet hics.org.

2

See, f or example, Nichols, P. L. & Anderson, V. E. (1973). Int ellect ual perf ormance, race and socioeconomic st at us. Soc. Biol. 20, 367–74. The aut hors conclude t hat ‘socioeconomic diff erences are largely responsible f or t he usually report ed diff erences in int ellect ual perf ormance’.

3

M edaw ar, P. (1982). Plut o’s Republic. Oxf ord: Oxf ord Universit y Press. Anot her common crit icism of IQ t est s arises f rom t he ‘Flynn eff ect ’, f irst not ed by Prof essor James Flynn in 1987 (Psychol. Bull. 101, 171) t hat t he average IQ of individuals has been rising st eadily since t he measurement w as f irst int roduced. In January 2002 he report ed t hat t he Flynn Eff ect is part icularly great in Brit ain, w hich has seen a 27 point increase in average IQ since World War II, compared t o a 24 point rise in t he US.

6 9

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

vocabulary. Yet ot hers measure how quickly an individual can solve a series of very simple problems, as w ell as w het her he or she is capable of solving seriously diff icult problems regardless of t ime pressure. The very diversit y of quest ions asked in t he various IQ t est s makes it hard t o accept t hat none of t hem succeeds in measuring any aspect of int elligence. But t he import ant observat ion is t hat scores on all t hese diff erent kinds of t est are posit ively correlat ed. In general, people w ho score highly on t est s of general know ledge or vocabulary w ill also t end t o obt ain high scores on t est s of abst ract reasoning or numerical series-complet ion t asks. Similarly, t hose w ho are poor at memorising a series of rapidly present ed numbers w ill also be poor at seeing w het her t w o t hree-dimensional diagrams are really view s of t he same object view ed f rom diff erent angles and slow t o delet e all t he ‘X’s in a list of random let t ers of t he alphabet . 7.4

There are t w o implicat ions of t his observat ion. One, f irst not ed by Spearman 4 but now accept ed by most t est ers of IQ, is t hat t he st at ist ical t echnique of f act or analysis,5 w hen applied t o people’s scores on a variet y of IQ t est s, w ill alw ays yield a subst ant ial general f act or, w hich account s f or much of t he variat ion in t heir scores.6 Spearman labelled t his f act or ‘g’, f or general int elligence, and argued t hat t he reason w hy diff erent IQ t est s correlat e w it h one anot her is because t hey all measure, t o a great er or lesser ext ent , a single underlying psychological or even neurological, process. The second implicat ion is t hat if IQ t est s f ail complet ely t o measure int elligence, it should be possible t o produce a diff erent t est , or set of t est s, t hat does measure int elligence, but does not correlat e w it h exist ing IQ t est s. Given t he diversit y of exist ing t est s t hat do correlat e w it h one anot her, t he challenge is not a t rivial one, and has not yet been met .

7.5

If perf ormance on every kind of IQ t est correlat es w it h perf ormance on every ot her kind of t est , it clearly f ollow s t hat t he score a person obt ains on one t est w ill be similar, but not ident ical, t o t he score t hey obt ain on anot her. Correlat ions bet w een diff erent kinds of t est range f rom about 0.35 t o about 0.85. It must equally f ollow, t heref ore, t hat a single, short t est w ill not t ell us all t hat w e might w ant t o know about a person’s IQ.

7.6

Diff erent t ypes of IQ t est may all be part ly measuring a f act or of general int elligence. But t hey are also measuring part ially dist inct cognit ive abilit ies. Fact or analysis of scores on a large range of t est s invariably reveals not only a general f act or, but also a number of more specif ic ‘group f act ors’, caused by t he f act t hat clust ers of sub-t est s show high correlat ions w it hin t he clust er, but low er correlat ions w it h sub-t est s in ot her clust ers. The general consensus is t hat one can dist inguish bet w een at least t he f ollow ing kinds of t est : ■ measures of abst ract reasoning or ‘f luid’ int elligence (Gf ) ■ vocabulary and general know ledge, or ‘cryst allised int elligence’ (Gc)

7 0

4

Spearman, C. (1927). The Abilit ies of M an. London: M acmillan.

5

Fact or analysis ref ers t o a group of st at ist ical procedures, based on correlat ion, w hich at t empt t o reduce a large amount of dat a t o t he smallest number of f act ors w hich can adequat ely account f or t he variance bet w een individuals on t he measures in quest ion. Fact or analysis is an import ant t ool f or areas of behavioural genet ics w here t he underlying component s are diff icult t o discern (e.g. personalit y assessment ). St rict ly speaking, f act ors are not t rait s as t hey merely represent regularit y in t he available dat a. The est ablishment of a valid t rait f rom f act or analysis requires addit ional inf erences t o be made.

6

See paragraphs 4.5 - 4.8 f or a def init ion of herit abilit y. Carroll, J. B. (1993). Human Cognit ive Abilit ies. Cambridge: Cambridge Universit y Press; Gould, S. J. (1996). The M ismeasure of M an. New York: Nort on.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

■ ret rieval or memory (Gr) ■ speed of processing (Gs).

CH A PTER

■ visuo-spat ial abilit y (Gv)

7 EV I D EN CE: I N TELLI GEN CE

The claim of t hose w ho support IQ t est s must be, how ever, t hat t he t est s do measure some import ant aspect s of int elligence. They have at t empt ed t o prove t his by show ing t hat people’s IQ scores are correlat ed w it h, or predict , many ot her t hings about t hem: how w ell t hey are now doing and w ill do lat er at school, how long t hey w ill st ay in f ull-t ime educat ion, t he kind of job t hey w ill obt ain and how w ell t hey w ill perf orm t hat job. Schoolchildren’s IQ scores correlat e in t he range 0.50 t o 0.70 w it h t heir current and subsequent educat ional at t ainment : f or example, t he correlat ion bet w een 11-year-olds’ IQ scores and t heir GCSE grades at age 16 is over 0.50.7 St udies in t he US have show n t hat t he correlat ion bet w een children’s IQ scores and t heir occupat ional st at us as adult s is also about 0.50. M oreover, t hese correlat ions cannot simply be at t ribut ed t o t he pervasive inf luence of f amily background. Alt hough t here is a correlat ion of around 0.30 bet w een IQ scores and socioeconomic st at us, Herrnst ein and M urray show ed t hat children’s IQ scores w ere subst ant ially more pow erf ul predict ors of t heir subsequent educat ional and occupat ional at t ainment s t han w as t heir f amily background.8 Their analyses have been vehement ly crit icised, and some of t hese crit icisms require some qualif icat ion of t heir argument s.9 But t heir cent ral conclusion st ands: IQ scores do predict , independent of f amily background, signif icant t hings about people’s lives. The predict ion is f ar f rom perf ect : even correlat ions of 0.50 leave much unexplained. M oreover, many of t hese correlat ions, f or example, bet w een IQ and measures of act ual perf ormance of a job are usually subst ant ially low er t han t his. This is hardly surprising. No one could sensibly doubt t hat success, w het her at school or in t he adult w orld, depends on many ot her t hings besides int elligence, including hard w ork, ambit ion, social skills and plain luck. But IQ is also a signif icant f act or.

TH E

7.8

O F

It has been argued t hat t here are import ant aspect s of human int elligence t hat IQ t est s f ail t o measure, such as creat ivit y, pract ical int elligence, social int elligence and emot ional int elligence. Some of t hese const ruct s are more securely grounded t han ot hers, and not all of t hem are w holly independent of IQ. How ever, t hose w ho support IQ t est s require only t hat t heir t est s should measure some reasonably import ant aspect s of int elligence. They can readily allow t hat t heir t est s leave some aspect s unmeasured.

REV I EW

7.7

Current findings: quantitative genetics 7.9

Bot h t est ers of IQ and researchers in behavioural genet ics agree t hat t he herit abilit y of IQ is relat ively high.10 That t here is a genet ic inf luence on IQ is suggest ed by t w o f indings: (i) M onozygot ic (M Z) t w ins resemble one anot her more closely t han dizygot ic (DZ) t w ins or siblings, and f ull siblings resemble one anot her more closely t han half siblings.

7

Brody, N. (1992). Int elligence. New York: Academic Press; Jensen, A. R. (1998). The g Fact or. West port , CT: Praeger.

8

Herrnst ein, R. J. & M urray, C. (1994). The Bell Curve. New York: Free Press.

9

Devlin, B. et al., edit ors. (1997). Int elligence, Genes and Success. New York: Springer-Verlag.

10

See t he f ollow ing f or summaries of research in t his f ield: Devlin, B., Daniels, M . & Roeder, K. (1997). The herit abilit y of IQ. Nat ure 388, 468–71; Plomin, R., DeFries, J. C., M cClearn, G. E. & M cGuff in, P. (2000). Behavioral Genet ics. 4t h ed. New York: Wort h; St ernberg, R. J., edit or. (2000). Handbook of Int elligence. Cambridge: Cambridge Universit y Press; Chipuer, H. M ., RoVine, M . & Plomin, R. (1990). LISREL modeling: Genet ic and environment al inf luences on IQ revisit ed. Int elligence 14, 11–29.

7 1

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

(ii) Individuals w ho are genet ically-relat ed cont inue t o resemble one anot her even w hen living apart . Tw o ot her observat ions suggest t hat environment al f act ors have an eff ect : (i) For all kinship cat egories, t hose living t oget her resemble one anot her more closely t han t hose living apart . (ii) Unrelat ed people living t oget her, adopt ive parent s and t heir adopt ed children or t w o adopt ed children living in t he same f amily, show a modest correlat ion in IQ. The dat a suggest , t heref ore, t hat bot h genet ic and environment al sources of variat ion cont ribut e t o variat ions in IQ. This may not seem a st art ling conclusion, but it is st ill disput ed by some crit ics, including t hose w ho quest ion t he validit y of est imat es of herit abilit y and t he met hodologies of quant it at ive genet ics.11 7.10 Adopt ion st udies have also provided evidence f or genet ic inf luences on IQ. Children given up f or adopt ion bef ore t he age of 6 mont hs cont inue t o resemble t heir biological mot her in IQ. Crit ics have appealed t o ‘select ive placement ’ t o explain t his, arguing t hat such children live in adopt ive homes caref ully select ed by adopt ion agencies t o mat ch t heir biological parent s’ circumst ances. If t his w ere a suff icient explanat ion, it w ould f ollow t hat t he resemblance bet w een adopt ed children and t heir adopt ive parent s in IQ should be at least as high as t hat bet w een t hese children and t heir biological parent s. How ever, research suggest s t hat t his is not t rue, and in t w o recent American st udies, t he correlat ion w it h t he biological parent s has been considerably higher t han w it h t he adopt ive parent s.12 7.11 DZ t w ins resemble one anot her in IQ somew hat more t han ot her siblings. An obvious explanat ion is t hat , being t he same age, t hey spend more t ime t oget her and share more experiences t han siblings of diff erent ages. In one small st udy, separat ed DZ t w ins w ere f ound t o resemble one anot her more closely t han separat ed siblings. This suggest s t hat t he shared prenat al environment may also be import ant .13 An alt ernat ive explanat ion is t hat some children classif ied as f ull siblings may in f act have diff erent biological f at hers. Bot h blood group and DNA t est s suggest t hat not all put at ive f at hers are t he act ual biological f at hers of t heir children. 7.12 The evidence f rom research in quant it at ive genet ics st rongly suggest s t hat a signif icant part of t he observed variat ion in IQ is genet ic in origin: t he herit abilit y of IQ is subst ant ially great er t han zero. How much great er? A suff icient ly accurat e answ er is t hat in modern West ern societ ies it is probably about 0.50, w it h a range of possible values f rom, say, 0.35 t o 0.75. For some t ime, t his has been t he consensus of virt ually all researchers in behavioural genet ics.14 How ever, t his f inding does not provide any inf ormat ion about

7 2

11

See Chapt er 4 (paragraphs 4.7-4.8). How, M . J. A. (1997). IQ in Quest ion. London: Sage; Wahlst en, D. & Got t lieb, G. The invalid separat ion of eff ect s of nat ure and nurt ure: Lessons f rom animal experiment at ion. In St ernberg, R. J. & Grigorenko, E. L., edit ors. (1997). Int elligence, Heredit y and Environment . Cambridge: Cambridge Universit y Press. pp. 163–92.

12

Loehlin, J. C. et al. Heredit y, environment , and IQ in t he Texas Adopt ion Project . In St ernberg, R. J. & Grigorenko, E. L., edit ors. (1997). Int elligence, Heredit y and Environment . Cambridge: Cambridge Universit y Press. pp. 163–92; Plomin, R., Fulker, D. W., Corley, R. & DeFries, J. C. (1997). Nat ure, nurt ure, and cognit ive development f rom 1 t o 6 years: A parent –off spring adopt ion st udy. Psychol Sci 8, 442–7.

13

Devlin, B., Daniels, M . & Roeder, K. (1997). The herit abilit y of IQ. Nat ure 388, 468–71

14

Plomin, R., DeFries, J. C., M cClearn, G. E. & M cGuff in, P. (2000). Behavioral Genet ics. 4t h ed. New York: Wort h.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

TH E EV I D EN CE: I N TELLI GEN CE

7.15 If t his is t rue, it w ill be necessary t o search specif ically f or individual genes associat ed w it h normal variat ion in IQ. The behavioural genet icist Robert Plomin and his colleagues have been engaged in just such a search f or t he past t en years. The diff icult ies should not be underest imat ed. Normal variat ions in IQ are expect ed t o be inf luenced by t he combined act ion of a number of genes, rat her t han by any one ‘major’ gene.16 As w e have already not ed, alt hough f act or analysis yields a general f act or g, IQ is not a unit ary const ruct , and must t heref ore be inf luenced by many diff erent genes. Suppose, f or t he sake of argument , t hat t he herit abilit y of IQ is 0.50 in t oday’s West ern populat ions. This means t hat half t he observed phenot ypic variat ion in IQ can be ascribed t o genet ic diff erences bet w een members of t hose populat ions. Suppose also t hat t here are 25 genes associat ed w it h t his variat ion in IQ, and t hat each has an equal, addit ive eff ect . Then each w ill be associat ed w it h 2% of t he observed variat ion in IQ. That is a small eff ect , not easily dist inguished f rom chance f luct uat ion.

O F

7.14 Some progress has been made in ident if ying genes linked t o inst ances of ment al ret ardat ion. One example is Fragile X syndrome, a disease caused by a small sect ion of base pairs on t he X chromosome being repeat ed t oo many t imes. How ever, as one comment at or has not ed: ‘Not a single gene involved in t he development of ment al ret ardat ion has been show n t o be associat ed w it h normal variat ion in IQ’.15 This is consist ent w it h t he general belief t hat mild ‘f amilial’ ret ardat ion is t he low er end of normal variat ion in IQ, but serious ret ardat ion is usually due t o quit e specif ic, relat ively rare causes – w het her genet ic or environment al in origin.

REV I EW

Current findings: molecular genetics

7

7.13 Int erest ingly, t here is some evidence t hat t he herit abilit y of IQ increases w it h age. Alt hough it might seem more plausible t o suppose t hat an inf ant ’s or young child’s int elligence is aff ect ed by t heir genet ic make-up, and t hat t he cumulat ive eff ect of environment al experience should become more import ant as children grow older, it is possible t hat some of t he genes associat ed w it h variat ions in IQ are not ‘sw it ched on’ unt il adolescence. Anot her possibilit y is t hat t he genet ic eff ect s on IQ are mediat ed by t he environment as w e develop, in ot her w ords, t hat w e act ively select environment s t hat complement our genot ypes, and t hat t he environment responds t o us diff erent ly depending on our genot ypes. If t his is t rue, it could mean t hat t he eff ect s of our genes are reinf orced over t ime and t hus appear t o be more import ant as w e get older.

CH A PTER

w hich genes inf luence int elligence, how many genes might be involved, or how t he genes have t heir eff ect .

7.16 The hist ory of t he search f or genes t hat inf luence such charact erist ics as schizophrenia or manic depression provides ample w arning of some likely problems. It is all t oo easy t o f ind some genet ic dif f erences bet w een t w o groups of people select ed f or t heir dif f erence in some phenot ypic t rait . Chance alone is almost bound t o produce some small dif f erences. They are not w ort hy of serious considerat ion unless replicat ed in f urt her independent samples. Wit h some f alse st art s, Plomin’s group does appear t o have

15

Grigorenko, E. Herit abilit y and int elligence. In St ernberg, R. J., edit or. (2000). Handbook of Int elligence. Cambridge: Cambridge Universit y Press.

16

Weiss, V. (1992). M ajor genes of general int elligence. Pers. Individ. Dif . 13, 1115–34, has argued f or a ‘major gene’ account of variat ion in IQ, but does not suppose t hat only one gene is involved.

7 3

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sat isf ied t his minimum requirement . One st udy compared t w o groups of about 50 children, bet w een 6 and 15 years old, one of average IQ (a mean of 103), a second of high IQ (a mean of 136).17 A syst emat ic search of t he long arm of chromosome 6 f ound a signif icant dif f erence bet w een t hem in t he f requency of dif f erent alleles of t he IGF2R gene.18 This dif f erence w as replicat ed in a second sample of 12-year-old children, 50 w it h an average IQ (a mean of 101) and anot her 50 w it h an est imat ed IQ of at least 160. The probabilit y of t he dif f erence arising by chance in bot h groups w as less t han 1 in 1,000. The same f our groups of children w ere also used in a second st udy t hat employed a dif f erent t echnique (DNA pooling across part icipant s) t o perf orm a syst emat ic search of chromosome 4.19 Eleven dif f erences w ere f ound bet w een t he init ial pair of high and average groups, and t hree of t hese w ere conf irmed in t he second pair of groups. A more recent and perhaps more st ringent st udy, how ever, has been less successf ul. The init ial pair of high and average IQ groups w as f ormed by combining t he t w o pairs of groups f rom t he earlier st udies. A large number of dif f erences in t he f requency dist ribut ion of microsat ellit e alleles w ere f ound bet w een t hese t w o groups (each comprising 101 individuals). How ever, very f ew of t hese dif f erences w ere replicat ed in a second pair of groups, and none in a t hird sample.20 7.17 At present , t he most one can say is t hat some dif f erences in t he f requencies of part icular alleles at part icular loci have been f ound bet w een high and average IQ groups, and t hat some of t hese dif f erences have been replicat ed in new samples. It w ill be import ant t o see if independent groups of researchers, st udying quit e dif f erent populat ions (all t he part icipant s in t hese st udies w ere w hit e, non-Hispanic Americans, most of t hem living in t he M idw est ), can replicat e t hese dif f erences. It is, moreover, import ant t o not e t hat t he ef f ect s observed, even if st at ist ically signif icant , are very small. The crit ical allele 5 w as f ound in less t han half of t he high-IQ children in t he init ial st udy, and in nearly one quart er of t he average IQ group. As t he aut hors properly acknow ledge: ‘IGF2R is not t he gene f or g but may be one of many genes responsible f or t he high IQ herit abilit y of g.’ 7.18 Finding genes associat ed w it h variat ions in IQ is not really surprising. If t he herit abilit y of IQ is approximat ely 0.50, t here must be such genes. The import ance of t he research is t hat it may make it possible t o w ork out how genet ic diff erences lead t o diff erences in IQ. That endeavour has barely st art ed. IGF2R is an insulin grow t h f act or gene. There is some, rat her cont ent ious, evidence implicat ing def ect ive glucose met abolism in Alzheimer’s disease, and some equally cont ent ious animal st udies have suggest ed t hat insulin may be involved in learning and memory.21 How ever, t his is a great dist ance f rom ascert aining t he w ay in w hich variat ion in t he IGF2R gene inf luences variat ion in IQ. 7.19 It is ext remely unlikely t hat researchers w ill f ind one or t w o genes t hat have a sizeable impact on variat ion in IQ w it hin t he normal range. The discovery of genes w it h small eff ect s w ill be very much harder t han t he discovery of mut at ions associat ed w it h serious ment al

17 18 19

20

21

7 4

Chorney, M . J. et al. (1998). A qualit at ive t rait locus associat ed w it h cognit ive abilit y in children. Psychol. Sci. 9, 159–66. IGF2R (insulin-like grow t h f act or II recept or). Fisher, P. J. et al. (1999). DNA pooling ident if ies QTLs on chromosome 4 f or general cognit ive abilit y in children. Hum. M ol. Genet . 8, 915–22. Plomin, R. et al. (2001). A genome-w ide scan of 1842 DNA markers f or allelic associat ions w it h general cognit ive abilit y: a f ive-st age design using DNA pooling and ext reme select ed groups. Behav. Genet . 31, 497–509. Wickelgren, I. (1998). Tracking insulin t o t he mind. Science 280, 517–19.

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REV I EW O F TH E EV I D EN CE: I N TELLI GEN CE

7.21 The search f or genes associat ed w it h variat ion in IQ w ill be made more diff icult , t o t he ext ent t hat genet ic eff ect s on IQ are not addit ive. We used earlier t he illust rat ive possibilit y t hat IQ w as aff ect ed by 25 genes, each w it h an equal, addit ive eff ect (paragraph 7.15). But some genet ic eff ect s, dominance and epist asis, are not addit ive. A recessive allele at a part icular locus w ill have one eff ect on t he phenot ype if it is accompanied by a dominant allele at t hat locus, and a quit e diff erent eff ect if accompanied by t he same recessive allele. M any harmf ul recessive genes are maint ained in t he populat ion because, alt hough harmf ul or even let hal w hen t w o copies are present , t hey may be benef icial if t hey are accompanied by a dominant allele w hich blocks t he harmf ul consequence. Epist asis ref ers t o t he possibilit y t hat phenot ypic charact erist ics are aff ect ed by part icular combinat ions of alleles at diff erent loci. For example, it might be t he case t hat allele 5 of t he IGF2R gene is associat ed w it h high IQ only if it is accompanied by part icular alleles at ot her loci. In t heir absence, it is accompanied by normal or even low IQ. If t hat w ere t rue, it w ould clearly be diff icult t o det ect , and replicat e, subst ant ial eff ect s.

7

7.20 The only securely replicat ed correlat ion is t hat bet w een IQ and t he overall volume of t he brain – w here t he correlat ion is about 0.40.22 But w e do not know w het her t hat eff ect is genet ic: improved nut rit ion and a more st imulat ing environment w ill bot h cause a signif icant increase in t he volume of rat s’ brains and improve t heir learning abilit y, and it is ent irely possible t hat t hese and ot her environment al variables have a similar impact on t he human brain.23 One recent st udy assessed t he herit abilit y of brain st ruct ure rat her t han cognit ive abilit y.24 The researchers compared t he densit y of grey mat t er (brain cell bodies) at specif ic regions in t he brains of t w ins and ot her individuals. Their f indings suggest t hat grey mat t er densit y is much more clearly correlat ed w it h int elligence at some cort ical sit es t han at ot hers. This area of genet ic research requires considerably more det ailed st udies bef ore f irm conclusions can be draw n.

CH A PTER

ret ardat ion. It may also be very much more diff icult t o uncover t heir mode of act ion. It seems reasonable t o suggest t hat t here may be some readily det ect able diff erences bet w een t he brains of t hose w it h an IQ below 50 and t hose w it h an IQ of 100 or more. Indeed, some such diff erences have already been observed. It seems rat her less likely t hat a gene associat ed w it h a 1% t o 2% variat ion in IQ in t he normal range w ill have such easily discernible eff ect s on brain f unct ion. Indeed, t he search f or correlat ions bet w een any measure of t he brain and variat ions in IQ in t he normal range has been long and remarkably unproduct ive.

7.22 Is t he genet ic variance underlying variat ion in IQ most ly addit ive? We not ed in Chapt er 4 t hat much research in behavioural genet ics assumes t his t o be t he case. But t w o relat ively sophist icat ed at t empt s t o model IQ variat ion, w hile bot h concluding t hat t he overall broadsense herit abilit y of IQ is about 0.50, also argue t hat addit ive genet ic variance account ed f or no more t han about 30% of t he overall variat ion in IQ, w hile non-addit ive eff ect s account ed f or some 20% .25

22

Vernon, P. A. et al. The neuropsychology and psychophysiology of human int elligence. In St ernberg, R. J., edit or. (2000). Handbook of Int elligence. Cambridge: Cambridge Universit y Press; Deary, I. J. (2000). Looking Dow n on Human Int elligence. Oxf ord: Oxf ord Universit y Press.

23

Renna, J. M . & Rosenzw eig, M . R. (1987). Enriched and Impoverished Environment s. New York: Springer-Verlag.

24

Thompson, P. M . et al. (2001). Genet ic inf luences on brain st ruct ure. Nat . Neurosci. 4, 1253–8.

25

Devlin, B., Daniels, M . & Roeder, K. (1997). The herit abilit y of IQ. Nat ure 388, 468–71; Chipuer, H. M ., RoVine, M ., & Plomin, R. (1990). LISREL modeling: Genet ic and environment al inf luences on IQ revisit ed. Int elligence 14, 11–29.

7 5

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

7.23 Alt hough w e observed in paragraph 7.3 t hat perf ormance on one kind of IQ t est is of t en posit ively correlat ed w it h perf ormance on ot hers, t hus ensuring t hat f act or analysis w ill f ind a sizeable general f act or, t his g is cert ainly not t he ent ire answ er t o t he quest ion of IQ. The cognit ive abilit ies measured by t est s of Gf , Gc, Gv and so on are part ially independent of one anot her. This is part icularly t rue at higher levels of IQ: scores on diff erent t ypes of IQ t est are more st rongly correlat ed in people of below average IQ, t han in t hose of above average IQ.26 Thus a high-IQ group may cont ain some people w it h much higher scores on one kind of t est , and ot her people w it h higher scores on anot her kind of t est . If t he genes associat ed w it h variat ions in scores on t hese diff erent t est s are diff erent , t here w ill be t hat much less chance of f inding genes consist ent ly associat ed w it h a high IQ score. To t hat ext ent , t he st rat egy of comparing a high-IQ group w it h an average-IQ group may be problemat ic. 7.24 There is evidence f or t he herit abilit y of diff erent cognit ive abilit ies, independent of any general f act or.27 How ever, Plomin and ot hers have argued t hat mult ivariat e genet ic analysis28 est ablishes t hat , t o a signif icant ext ent , t he same genes aff ect diff erent cognit ive abilit ies.29 To t he ext ent t hat scores on t est s of diff erent cognit ive abilit ies are all posit ively correlat ed, it is indeed possible t hat all cognit ive abilit ies depend on a common underlying process – t he subst rat e of g, and t hat genet ic eff ect s on g are common t o all t est s. But t hat is cert ainly not a necessary conclusion. It is t rue t hat t est s of diff erent cognit ive abilit ies are all correlat ed: but t he reason f or t he correlat ions bet w een various pairs of t est s may be diff erent . The general f act or ext ract ed by f act or analysis is no more t han a mat hemat ical represent at ion of t he f act t hat all t hese t est s correlat e w it h one anot her: it does not prove t hat t here is a single reason w hy t hey should do so, in ot her w ords, t hat t here is any process or processes common t o all t est s. It is ent irely possible t hat t he genes associat ed w it h w hat one pair of t est s shares in common are diff erent f rom t hose genes associat ed w it h w hat is common t o ot her pairs of t est s.

Directions for future research 7.25 The st rat egy of t he research programme of Plomin and his colleagues has been t o ident if y alleles associat ed w it h high, as opposed t o average, IQ. A diff erent st rat egy might be able t o locat e genes associat ed w it h below average IQ, in t he range 80 t o 100. As not ed earlier, since scores on t est s of diff erent cognit ive abilit ies are more highly correlat ed in t hose of below -average, rat her t han above-average, IQ, t here w ould seem t o be more chance of such research f inding genes associat ed w it h variat ions in g or any general f act or of int elligence. There is, how ever, a grow ing belief t hat t he genet ic variance in IQ in t he low er range of scores may be due t o mildly delet erious mut at ions rat her t han genes t hat are associat ed w it h variat ion in IQ scores in t he normal range.30 Recent evidence suggest s t hat t he number of such mut at ions w hich all people carry and t he rat e at w hich new mut at ions

7 6

26

Det t erman, D. K. & Daniel, M . H. (1989). Correlat ions of ment al t est s w it h each ot her and w it h cognit ive variables are highest f or low IQ groups. Int elligence 13, 349–59.

27

Alarcon, M . et al. (1998). M ult ivariat e pat h analysis of specif ic cognit ive abilit ies dat a at 12 years of age in t he Colorado Adopt ion Project . Behav. Genet . 28, 255–64.

28

M ult ivariat e genet ic analysis involves t he simult aneous analysis of a number of phenot ypes, w hich allow s f or t he covariance bet w een phenot ypes t o be broken dow n int o genet ic and environment al sources. This at t empt s t o est ablish how w ell t he genet ic or environment al values of one phenot ype predict t he genet ic or environment al values of anot her phenot ype.

29

Pet rill S. A. (1997). Current Direct ions in Psychological Science 6, 96–9.

30

Alarcon, M . et al. (1998). M ult ivariat e pat h analysis of specif ic cognit ive abilit ies dat a at 12 years of age in t he Colorado Adopt ion Project . Behav. Genet . 28, 255–64.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

CH A PTER 7 REV I EW

occur in each generat ion are much higher t han previously supposed.31 If such mut at ions act t o increase suscept ibilit y t o pat hogens or ot her environment al f act ors, or decrease in any w ay t he overall eff iciency of t he individual, one w ould expect t hem t o cont ribut e t o a below -average IQ, and t hat variat ion in IQ in t his range may be caused by variat ion in t he number and nat ure of such mut at ions. This w ould help t o explain w hy t here is a signif icant correlat ion, af t er cont rolling f or social class, bet w een IQ and such physical f act ors as overall healt h and bodily symmet ry.32 If all t his is t rue, it w ill be very diff icult t o ident if y part icular alleles associat ed w it h below -average IQ in t he populat ion as a w hole: a w hole range of diff erent genot ypes, w it h quit e diff erent mildly delet erious mut at ions, may be implicat ed.

O F TH E EV I D EN CE: I N TELLI GEN CE

31

See Kondrashov, A. S. (1995). Cont aminat ion of t he genome by very slight ly delet erious mut at ions: w hy have w e not died 100 t imes over? J. Theor. Biol. 175, 583–94 and Sunyzev, S. et al. (2001). Predict ion of delet erious human alleles. Hum. M ol. Genet . 10, 591–7. The lat t er comes t o t he conclusion t hat ‘t he average human genot ype carries approximat ely 103 damaging non-synonymous SNPs t hat t oget her cause a subst ant ial reduct ion in f it ness’. In ot her w ords, every one of us is genet ically def ect ive t o some ext ent .

32

Lubinski, D. & Humphreys, L. G. (1992). Some bodily and medical correlat es of mat hemat ical gif t edness and commensurat e levels of socioeconomic st at us. Int elligence 16, 99–115; Furlow, B. F., Armijo-Prew it t , T., Gangest ad, S. W. & Thornhill, R. (1997). Fluct uat ing asymmet ry and psychomet ric int elligence. Proceedings of t he Royal Societ y of London B. 264, 823–9.

7 7

Chapter Review of t he evidence: personalit y

8

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Background 8.1

PERSO N A LI TY

The dominant view at present put s t he number of independent personalit y t rait s at f ive; t his is called t he ‘Big Five’ model of personalit y. The ‘Big Five’ t rait s are: Neurot icism, Ext raversion, Agreeableness, Conscient iousness and Openness t o Experience (see Table 8.1).2 Each t rait has a normal dist ribut ion of scores. These f ive t rait s, or f act ors, are commonly ref erred t o as ‘dimensions of personalit y’. There is disagreement among psychologist s about t he number of core personalit y t rait s; alt ernat ive view s range f rom t hree t o seven. The Brit ish psychologist Hans Eysenck originally suggest ed t hree – Neurot icism, Int roversion and Psychot icism. How ever, in t he Big Five M odel, Psychot icism is broken dow n int o t hree separat e f act ors (Agreeableness, Conscient iousness and Openness t o Experience). Impulsivit y (sensat ion-seeking) is also somet imes separat ed out . It is import ant t o not e t hat t hese t rait s are used f or descript ive convenience, rat her t han because t here is evidence t hat t hey have dist inct biological causes or pat hw ays t hat aff ect personalit y.

EV I D EN CE:

8.3

TH E

Diff erent aspect s of personalit y can be described at diff erent levels. One can eit her choose t he highest level, at w hich all t he t rait s are independent of one anot her, or a variet y of low er levels, at w hich t he t rait s are t o varying degrees correlat ed w it h each ot her. Genet ic research int o personalit y has largely concent rat ed on t he f irst , highest level; w hat might be t ermed ‘global’ t rait s.

O F

8.2

REV I EW

Trait definition and measurement

8

Personalit y has long been a f ocus of research in various disciplines. M any measures of personalit y originat ed out side psychiat ry. For example, t he f irst personalit y measure, devised in 1919, w as used in det ermining ment al f it ness f or milit ary service. Since t hen many measures of personalit y, of diff ering qualit y, have been developed, such as t he M innesot a M ult iphasic Personalit y Invent ory (M M PI). How ever, it should be not ed t hat t he prime purpose of psychological t est s of personalit y w as not f or use in psychiat ry but rat her t o build a t heory of personalit y.

CH A PTER

Review of t he evidence: personalit y

1

Table 8.1: The ‘Big Five’ Personality Traits Trait

Descript ors at

M anif est at ion of t rait

high end of scale Neurot icism

Anxious Depressed Feeling guilt y Having low self -est eem Tense Shy

Individuals w it h high scores on t his t rait are likely t o develop one of a range of neurot ic psychiat ric disorders, including generalised anxiet y disorder, agoraphobia, major depression and obsessive-compulsive disorder. There is

1

The mat erial in t his chapt er is t aken f rom a paper commissioned by t he Nuff ield Council on Bioet hics f rom Prof essor Jeff rey Gray, Emerit us Prof essor at t he Inst it ut e of Psychiat ry, Kings College London. The paper is available on t he Council’s w ebsit e: w w w.nuff ieldbioet hics.org.

2

Since t erms such as Neurot icism are also in common usage, w e adopt t he pract ice of psychologist s of capit alising t he f irst let t er of each t rait in order t o indicat e t hat w e are ref erring t o t hese t rait s as t hey are def ined and st udied by psychologist s.

8 1

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8 2

M oody Agit at ed Suspicious Host ile Emot ional

considerable comorbidit y bet w een t hese neurot ic disorders (but not bet w een t hem and t he psychot ic disorders, such as schizophrenia or mania).3

Int roversion– Ext raversion 4

Sociable Lively Act ive Assert ive Caref ree Dominant Vent uresome Opt imist ic Impulsive Sensat ion-seeking

Individuals w it h high scores f or Int roversion t end t o be quiet and reserved, int rospect ive, dist ant except w it h int imat e f riends, reliable, non-impulsive, serious, liking order, emot ionally rest rained, non-aggressive, moral and somew hat pessimist ic. High scorers on Ext raversion in cont rast t end t o be sociable, impulsive, sensat ion seekers, liking of change, easy going, opt imist ic, aggressive and can be unreliable.

Agreeableness

Trust ing St raight f orw ard Alt ruist ic Compliant M odest Tender-minded

Individuals w it h high scores on t his t rait are st raight f orw ard and f rank, co-operat ive, yielding rat her t han aggressive in conf lict , modest and unpret ent ious, caring, nurt uring, and support ive and t end t o see ot hers as honest and t rust w ort hy.

Conscient iousness

Product ive Orderly Dependable Having a high level of aspirat ion Consist ent Rat ional

Highly conscient ious people are goalorient ed and eff icient . They are dependable, w ell-organised, met hodical and f ocused. Being rule-orient ed, t hey avoid disorder and impulsive behaviour.

Openness t o Experience

Given t o f ant asy Aest het ically react ive Sensit ive t o int erpersonal cues Concerned w it h philosophical problems M oralist ic Socially poised

High scorers are f lexible and broad-minded individuals w ho are creat ive, imaginat ive and int ellect ual. They like t o t ry new opt ions, seek out variet y and f ind rew ard in learning and developing new ideas. They avoid sit uat ions t hat are highly , st ruct ured, rigid or cont rolled.

3

Quant it at ive genet ics research has show n t hat t he genet ic inf luences on Neurot icism aff ect almost exclusively it s comorbidit y w it h ot her t rait s as dist inct f rom t he liabilit y t o any one part icular disorder. The st udies show also t hat scores on self -report scales of Neurot icism provide a good measure of t he herit able component of t he comorbidit y of neurot ic disorders. Thus, t his t rait is best regarded as one of suscept ibilit y t o t he ent ire gamut of neurot ic disorders, w it h t he act ual nat ure and occurrence of such a disorder depending upon lif e event s.

4

This is the best established of all personality traits. Like Neuroticism, Extraversion has been embedded in several, experimentally testable, neurobiological theories and progress is being made towards identifying the underlying brain mechanisms.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

8.5

Using f act or analysis, it is possible t o det ermine how many independent f act ors or t rait s exist w it hin a given body of dat a, but not how t hese f act ors are relat ed. Thus, f rom t he result s of descript ive st udies alone, w e are unable t o t ell w het her a given dimension of personalit y merely provides us w it h a convenient set of coordinat es w it hin w hich t o locat e an individual’s personalit y (as, say, East –West and Nort h–Sout h are used as convenient set s of coordinat es w it hin w hich t o f ix spat ial locat ion), or w het her it has a basis in underlying causal realit y (as, say, up–dow n has a basis in t he f orce of gravit y). Because of t his ambiguit y, many of t he t rait t erms used in personalit y research (even w hen t hey all operat e at t he highest , dimensional, level) do not ref lect ent irely diff erent t rait s, but rat her rot at ions of one anot her. For example, t he t rait of novelt y-seeking blends some low er-order t rait s t hat , in alt ernat ive descript ive syst ems, make up Ext raversion w it h ot hers t hat make up Psychot icism.

8.6

A f urt her problem is t hat dif f erent invest igat ors may ref er t o w hat is essent ially t he same dimension by dif f erent names (of t en ref lect ing dif f erent t heories int o w hich t he dimension has been embedded). There are no clear pre-exist ing signpost s t o suggest f or w hich personalit y t rait s researchers w ill most likely f ind genet ic inf luences. How ever, if t here is a subst ant ial herit able component t o a given personalit y t rait , t hen t his can it self provide bot h an ext ernal crit erion by w hich t o validat e t he f act or purport ing t o represent t he t rait as w ell as a t heoret ical f ramew ork f or predict ion and experiment t o est ablish it s causal realit y. For example, if research in quant it at ive genet ics show s a subst ant ial genet ic inf luence on variat ion in Neurot icism, t his simult aneously provides support f or t he realit y of t he underlying t rait of Neurot icism, f or t he t est s by w hich it is measured, and f or t he f act or-analyt ic solut ion t hat has yielded t he f act or of Neurot icism.

8

M ost research indicat es t hat t he t w o most robust t rait s are t hose of Neurot icism and Int roversion–Ext raversion. These are highly replicable, t hey account f or a considerable port ion of t he variance across a very w ide range of measures, and t hey can each be reliably measured by relat ively short self -report scales ideally suit ed t o large-scale genet ic st udies.

CH A PTER

8.4

REV I EW O F TH E EV I D EN CE: PERSO N A LI TY

Current findings: quantitative genetics 8.7

The t w o most import ant conclusions t o emerge t o dat e f rom quant it at ive genet ic st udies of personalit y are of broad generalit y. First , across a range of t rait s, herit abilit y est imat es f rom t w in st udies lie in t he range 0.30–0.50 5 (t hough est imat es f rom adopt ion st udies are consist ent ly low er, suggest ing t hat non-addit ive genet ic variance may have an import ant role in personalit y). 6 This is t he result obt ained f or Neurot icism, Ext raversion, Conscient iousness, Openness t o Experience and Agreeableness (t hough in t he lat t er case, herit abilit y in one st udy w as est imat ed at only 0.12). Sensat ion-seeking has been report ed t o have somew hat higher herit abilit y, about 0.60. This consist ency in t he pat t ern of result s is surprising. Bet w een t hem, t hese f indings, ext ending as t hey do over t he ent ire Big Five model, cover all know n personalit y t rait s. Thus, t he genet ic cont ribut ion t o personalit y is t hought t o be subst ant ial and appears t o be roughly equal across all aspect s of personalit y.

5

Plomin, R., DeFries, J. C., M cClearn, G. E. & M cGuff in, P. (2001). Behavioral Genet ics. 4t h ed. New York: Wort h.

6

Bouchard, T. J. Jr. & Loehlin, J. C. (2001). Genes, Evolut ion, and Personalit y. Behav. Genet . 31, 243–73. Anot her int erest ing f eat ure of herit abilit y calculat ions t hat t he aut hors discuss is t he variat ion bet w een sexes.

8 3

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8.8

There is no a priori reason t o expect all personalit y t rait s t o be inf luenced equally by genet ic causes. How ever, t he result s obt ained t o dat e are mut ually consist ent and apparent ly robust . It is possible t hat t he unif ormit y of genet ic inf luence is an art ef act due t o t he imperf ect alignment of personalit y t rait s derived f rom descript ive, f act or-analyt ic st udies. Fut ure research combining genet ic and f act or-analyt ic met hods may be able t o improve t his alignment . In t hat case, t rait s w ould emerge w it h great er est imat es of herit abilit y t han t he 0.30–0.50 t hat have emerged so f ar, but t hese w ould be balanced by ot hers w it h lesser est imat es of herit abilit y (w it h t he t ot al genet ic cont ribut ion across t he w hole of personalit y space necessarily being conserved).

8.9

Secondly, quant it at ive genet ics research has show n t hat w hen considering t he environment al eff ect s on personalit y, non-shared environment al f act ors have t he largest eff ect (see paragraphs 4.9–4.10 w hich explain t he diff erence bet w een shared and nonshared environment ).7 How ever, unless specif ic measures of environment al risk f act ors are included in t hese st udies, lit t le can be surmised as t o w hat t hese inf luences might be, or even t he degree t o w hich t hey are likely t o yield t o syst emat ic analysis.

Current findings: molecular genetics 8.10 A large number of genes are know n t o inf luence brain f unct ion. M oreover, in t he present st at e of know ledge, a plausible hypot hesis can be const ruct ed t o link almost any of t he know n genes w it h virt ually any aspect of personalit y. And many ot her genes w it h inf luence on t he brain remain t o be discovered and so cannot yet serve as candidat es. 8.11 There are many grounds f or believing t hat levels of anxiet y, psychot icism or impulsivit y may in part ref lect dif f ering levels of f unct ioning of part icular neurot ransmit t ers in t he brain. Prominent in t his respect are t he monoamine t ransmit t ers: dopamine, serot onin and noradrenaline. Thus, an experiment er may invest igat e w het her t rait scores dif f er as a f unct ion of a polymorphism in a gene t hat det ermines, f or example, t he rat e of synt hesis or t ransport of one of t hese neurot ransmit t ers or t he st ruct ure of t he recept ors upon w hich t he neurot ransmit t er act s. 8.12 There has recent ly been a f lurry of st udies t hat claim t o ident if y part icular genet ic inf luences on personalit y t rait s. Associat ions have been report ed bet w een: (i) novelt yseeking and a polymorphism in t he gene f or t he D4 recept or (one of several dif f erent t ypes of recept or) f or dopamine;8 and (ii) anxiet y and a polymorphism in t he gene f or t he serot onin t ransport er.9 (The serot onin t ransport er t erminat es t he act ion of serot onin by t ransport ing it f rom t he synapt ic junct ion back int o t he cell t hat has just released it .) There have since been numerous at t empt s t o replicat e t hese f indings, w it h very mixed result s. Several of t hese experiment s, especially t hose report ing negat ive out comes, have used samples t oo small t o yield conclusive result s. How ever, t here have now been a suf f icient number of posit ive replicat ions of t he init ial report concerning

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7

Riemann, R., Angleit ner, A. & St relau, J. (1997). Genet ic and environment al inf luences on personalit y: a st udy of t w ins reared t oget her using t he self - and peer-report NEO-FFI scales. J. Pers. 65, 449–76.

8

Ebst ein, R. P. et al. (1995). Dopamine D4 recept or exon III polymorphism associat ed w it h t he human personalit y t rait of novelt y-seeking. Nat . Genet . 12, 78–80; Benjamin, J. et al. (1996). Populat ion and f amilial associat ion bet w een t he D4 dopamine recept or gene and measures of novelt y-seeking. Nat . Genet . 12, 81–4. See also paragraphs 5.9-5.10.

9

Lesch, K. P. et al. (1996). Associat ion of anxiet y relat ed t rait s w it h a polymorphism in t he serot onin t ransport er gene regulat ory region. Science 274, 1527–31.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

TH E EV I D EN CE: PERSO N A LI TY

8.14 Numerous animals have been t est ed in genet ic st udies of personalit y, including primat es, rat s, mice and even f ish. The most developed animal model is t hat of Emot ionalit y, w hich is used as an analogue of t he human t rait of Neurot icism. Neurot icism has been embedded w it hin several neurobiological t heories w hich can be t est ed experiment ally; and t here has been good progress in underst anding t he nat ure of t he syst ems in t he brain w hose f unct ioning most likely underlies scores on t he t rait . Across a w ide range of behavioural t est s w it h good credent ials as put at ive measures of anxiet y, rodent s w hich obt ain high scores on one t est are likely also t o get high scores on t he ot hers. Furt hermore, it has proved possible t o inbreed and select ively breed st rains of mice or rat s such t hat t hey reliably obt ain high (or low ) scores on such t est s, generat ion af t er generat ion. It remains t o be demonst rat ed, how ever, t hat t he genes w hich inf luence Emot ionalit y in rodent s are similar t o t hose t hat det ermine human Neurot icism.

O F

Current findings: research involving animals

REV I EW

8.13 Several st udies of QTLs f or Neurot icism are in progress around t he w orld. QTL st udies in humans, t hat use sibling pairs and linkage st rat egies, require very large numbers; around 20,000 pairs of siblings w ho eit her bot h score high (or low ) on t he t rait (concordant pairs), or one of w hom scores high and t he ot her low (discordant pairs).11 Result s f rom t hese st udies are likely t o become available in t he next year. In t he light of t he result s f rom rodent st udies (see paragraphs 8.14 – 8.16) it is likely t hat at least some of t hese result s w ill be posit ive. How ever, t o move beyond t he ident if icat ion of a QTL t o t he act ual gene w it h w hich it is associat ed remains a very diff icult t echnical problem t hat has not so f ar been achieved f or any QTL t hought t o aff ect human behaviour.

8

Quantitative trait loci (QTL) research

CH A PTER

t he serot onin t ransport er gene t hat t his f inding is reliable.10 These st udies concur in show ing t hat alleles of t he serot onin t ransport er gene w hich result in reduced serot onin re-upt ake are associat ed w it h higher anxiet y. These result s are, how ever, unexpect ed, given t hat drugs w hich reduce serot onin re-upt ake, such as Prozac, are used t o alleviat e bot h depression and anxiet y. As not ed in paragraph 5.10, t he evidence f or a link bet w een t he DRD4 gene and novelt y-seeking does not seem convincing, despit e t he init ial f indings.

8.15 The f irst QTL st udy of a behavioural t rait , report ed by Flint et al,12 invest igat ed Emot ionalit y in mice. This st udy w as an import ant demonst rat ion of principle. Nearly 1,000 mice w ere derived f rom int ercrossing t w o highly inbred, select ively bred st rains w it h very high and very low scores on behavioural t est s of Emot ionalit y. The int ercrossing mixes t he genes f rom t hese t w o parent al st rains; and t he DNA markers can t hen be used t o det ermine w hich genes

10

Greenberg, B. D. et al. (2000). Associat ion bet w een t he serot onin t ransport er promot er polymorphism and personalit y t rait s in a primarily f emale populat ion sample. Am. J. M ed. Genet . (Neuropsychiat ric. Genet .) 96, 202–16; Sher, L. et al. (2000). Pleiot ropy of t he serot onin t ransport er gene f or seasonalit y and neurot icism. Psychiat r. Genet . 10, 125–30; Osher, Y. et al. (2000). Associat ion and linkage of anxiet y-relat ed t rait s w it h a f unct ional polymorphism of t he serot onin t ransport er gene regulat ory region in Israeli sibling pairs. M ol. Psychiat ry 5, 216–19; M elke, J. et al. (2001). Serot onin t ransport er gene polymorphisms are associat ed w it h anxiet y-relat ed personalit y t rait s in w omen. Am. J. M ed. Genet . (Neuropsychiat ric. Genet .) 105, 458–63; Jang, K. J. et al. (2001). Covariance st ruct ure of neurot icism and agreeableness: a t w in and molecular genet ic analysis of t he role of t he serot onin t ransport er gene. J. Pers. Soc. Psychol. 81, 295–304; Du, L., Bakish, D. & Hrdina, P. D. Gender diff erences in associat ion bet w een serot onin t ransport er gene polymorphism and personalit y t rait s. Psychiat r. Genet . 10, 159–64.

11

Risch, N. & M erikangas, K. (1996). The f ut ure of genet ic st udies of complex human diseases. Science 273, 1516–17.

12

Flint , J. et al. (1995). A simple genet ic basis f or a complex psychological t rait in laborat ory mice. Science 269, 1432–5.

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in t he off spring have been inherit ed f rom each st rain. QTLs w ere ident if ied by correlat ions bet w een t hese markers and scores on various behavioural t est s f or Emot ionalit y. Three QTLs w ere ident if ied, having t he import ant propert y of pleiot ropy: t hat is, each w as associat ed w it h several diff erent behavioural measures, rat her t han w it h any single it em of behaviour. The QTL w it h t he great est eff ect w as sit uat ed on chromosome 1. This f inding has since been replicat ed several t imes. Addit ional analysis using quant it at ive genet ics t echniques assessed t he amount of t he variance in scores on t he t est s t hat could be at t ribut ed t o genet ic f act ors t o be, at most (depending on t he part icular behavioural measure), about 30% . Import ant ly, t he addit ive eff ect s of t he ident if ied QTLs, t aken t oget her, w ere able t o account f or nearly all of t his genet ic variance. Finally, t he st udy conf irmed t he conclusion, derived f rom mat hemat ical simulat ions, t hat (given a large enough sample size) t he QTL approach is able t o ident if y QTLs t hat account f or a very small port ion of t he phenot ypic variance – as lit t le as about 3% in t he Flint et al st udy. 8.16 Even f or t he w ell-replicat ed research on t he QTL on chromosome 1, how ever, it has not yet been possible t o ident if y t he gene involved; alt hough subsequent w ork has narrow ed dow n t he relevant chromosomal region. Unt il t he gene in quest ion has been ident if ied, it is not possible t o t est it s eff ect s in humans. If t he gene w ere ident if ied in bot h animals and humans, t his w ould permit invest igat ion of t he causal chain by w hich t he gene cont ribut es t o t he specif icat ion of values on t he t rait . In t his respect , t he rat is pref erred t o t he mouse, since much more is know n about t he behavioural f unct ions of t he brain in rat s. Flint ’s group have now ident if ied a QTL in t he rat w hich appears t o be relat ed t o Neurot icism, since it has pleiot ropic eff ect s across a large bat t ery of behavioural t est s t hat are sensit ive t o t he eff ect s of drugs used in human beings t o reduce anxiet y.13

Future directions for research 8.17 Fut ure research in behavioural genet ics in t he f ield of personalit y t rait s is likely t o f ocus on t he use of molecular genet ic research t echniques t o ident if y candidat e genes and regions of DNA t hat have an eff ect . If such genes are ident if ied, t hey could provide t he basis f or experiment s aimed at det ermining t he neurobiological pat hw ays by w hich genet ic inf luences are brought t o bear. Det ailed know ledge of t he genes t hat aff ect personalit y w ould t hen, in t urn, provide t he basis f or invest igat ion of non-genet ic inf luences on personalit y.

13

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Fernandez-Teruel, A. et al. (2002). A quant it at ive t rait locus inf luencing anxiet y in t he laborat ory rat . Genome Res. 12, 618–26.

Chapter Review of t he evidence: ant isocial behaviour

9

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

1

M ent al healt h clinicians int erest ed in pat hological behaviour concept ualise ant isocial behaviour as a ment al disorder. As a result , t heir def init ions require t hat t he behaviour is seriously harmf ul t o ot hers, involves a number of diff erent t ypes of ant isocial act s, or has persist ed over a long t ime period. The primary labels assigned t o ant isocial pat hology are: conduct disorder, in young people under 18; ant isocial personalit y disorder, in adult s; and psychopat hy, also in adult s. These clinical def init ions t end t o apply t o f ew er t han 5–10% of t he populat ion, depending on age. Such ment al disorders are t ypically measured as diagnost ic cat egories (eit her t he individual meet s t he crit eria f or t he disorder, or not ). How ever, t here are inst rument s t hat measure t hese disorders as cont inuous dist ribut ions, in w hich t he number of diff erent sympt oms exhibit ed is count ed. Examples of dimensional inst rument s t hat have been used in research in behavioural genet ics w it h children include t he Achenbach Child Behaviour Checklist f or ext ernalising behaviours and t he Rut t er ant isocial scale. An example of a dimensional measure used in research w it h adult s is t he M innesot a M ult iphasic Personalit y Invent ory (M M PI) psychopat hy scale, w hich w as discussed brief ly in paragraph 8.1 in relat ion t o personalit y t est s. Inf ormat ion about t he presence or absence of sympt oms is usually gat hered about young children t hrough report s f rom parent s and t eachers, about older children and adolescent s t hrough parent s, t eachers and self -report s, or about adult s t hrough self -report s or clinical records.

9.4

Criminologist s concept ualise ant isocial behaviour as behaviour t hat is against t he law. As a result , t heir def init ions do not require t here t o be serious harm, a variet y of act s or persist ence. Nonet heless, in pract ice most criminologist s discriminat e bet w een t he minor off ender w ho commit s a one-off off ence and t he more ext reme alt ernat ives, namely

1

BEH AV I O U R

9.3

A N TI SO CI A L

Ant isocial behaviour is st udied by diff erent disciplines, each of w hich has it s ow n perspect ive on t he def init ion and measurement of w hat is ant isocial. M ent al healt h clinicians, criminologist s and personalit y psychologist s concept ualise and measure ant isocial behaviour somew hat diff erent ly, but all t hree f ields share in common t he underlying assumpt ion t hat ant isocial behaviour is behaviour t hat violat es t he right s and saf et y of ot hers.

EV I D EN CE:

9.2

TH E

Trait definition and measurement

O F

Various biological explanat ions of ant isocial and criminal behaviour have been off ered hist orically but none have st ood up t o rigorous analysis or off ered successf ul or accept able solut ions t o t he cont inuing problems caused by such behaviour. It is w idely accept ed t hat crime and ant isocial behaviour are t he result s of many diff erent inf luences, some of w hich, such as deprivat ion and povert y, are already t he t arget of exist ing int ervent ions. This chapt er explores at t empt s by researchers in behavioural genet ics t o examine a pot ent ial genet ic cont ribut ion t ow ards such behaviour.

REV I EW

9.1

9

Background

CH A PTER

Review of t he evidence: ant isocial behaviour

The mat erial in t his Chapt er is t aken f rom a paper by Prof essor Terrie M off it t , Inst it ut e of Psychiat ry, King’s College London. The paper is available on t he Council’s w ebsit e: w w w.nuff ieldbioet hics.org.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

violent , prof icient or persist ent recidivist ic off enders, because t he lat t er are of great er concern in policy t erms. The primary labels assigned are: delinquency, in juveniles, w hose age is legally def ined; and crime, in adult s. These legal def init ions t end t o apply t o bet w een 20–30% of t he populat ion, depending on age. These const ruct s are somet imes measured as legal cat egories (eit her t he individual has been convict ed at court , or not ). How ever, t hey are more commonly measured as cont inuous dist ribut ions, in w hich t he number of diff erent illegal behaviours commit t ed and t he f requency w it h w hich t hey have been commit t ed are count ed. Inf ormat ion about t he presence or absence of illegal act s is usually gat hered t hrough self -report s or police records (about older children and adolescent s), or t hrough self -report s or court convict ion records (about adult s).

9 0

9.5

Personalit y psychologist s concept ualise ant isocial t rait s in t erms of at t it udes, belief s, int erest s and pref erences t hat indicat e an inclinat ion t o t ake advant age of or harm ot hers, or a w illingness t o break t he law. As a result , t heir def init ions do not require t hat any ant isocial act has occurred. Personalit y psychologist s t hink of t he ‘aggressiveness’ of humans as a charact erist ic analogous t o t he ‘brit t leness’ of glass; alw ays t here, but not necessarily expressed. Alt hough older personalit y measures t hat w ere labelled ‘aggression’ somet imes included it ems asking about act ual physical act s, it has been show n t hat such act s are not int egral t o t he measures. The primary labels assigned are host ilit y, w hich ref ers t o t emper, socialisat ion, w hich includes such t rait s as conscient iousness and honest y, or aggression. Def init ions of personalit y t rait s t end t o apply t o t he ent ire populat ion; t he high end of an ‘aggression’ scale may indicat e ent husiasm f or aggression w hereas t he low end may indicat e t imidit y. These personalit y const ruct s are virt ually never measured as discret e cat egories, because a f undament al assumpt ion about personalit y t rait s is t hat t hey are cont inuously dist ribut ed in t he populat ion. They are generally measured using checklist s w hich count t he number of diff erent ant isocial at t it udes endorsed by t he respondent . Examples of dimensional inst rument s t hat have been used in research in behavioural genet ics include t he M ult idimensional Personalit y Quest ionnaire (M PQ) aggression scale, t he Buss–Durkee host ilit y scales, and t he Calif ornia Psychological Invent ory (CPI) socialisat ion scale. Inf ormat ion about ant isocial personalit y t rait s is usually gat hered t hrough self -report s about older adolescent s and adult s.

9.6

Alt hough t he discussion above highlight s dif f erences bet w een t he t hree w ays of concept ualising and measuring ant isocial behaviour, research t hat has crossed disciplines has repeat edly show n t hat clinical, legal and personalit y measures are moderat ely t o st rongly relat ed t o each ot her. For example, aggressiveness measured in adolescence is st rongly correlat ed w it h lat er court convict ion f or violent criminal off ending in adult hood, as w ell as w it h psychiat ric diagnosis of ant isocial personalit y disorder.2,3 M oreover, as w e shall see, est imat es of genet ic and environment al inf luences on t he t hree t ypes of measure are more similar t han diff erent .

9.7

Classif ying individuals int o dichot omous cat egories based on t heir ant isocial behaviour is f raught w it h diff icult y and generally classif icat ion is not st rongly reliable. Is an individual a psychopat h, or not ? Is an individual a criminal, or not ? Does he or she have a diagnosis

2

M off it t , T. E., Krueger, R. F., Caspi, A. & Fagan, R. W. (2000). Part ner abuse and general crime: How are t hey t he same? How are t hey diff erent ? Criminology 38, 201–35.

3

Krueger, R. F., Caspi, A., M off it t , T. E., Silva, P. A. & M cGee, R. (1996). Personalit y t rait s are diff erent ially linked t o ment al disorders: A mult i-t rait /mult i-diagnosis st udy of an adolescent birt h cohort . J. Abnorm. Psychol. 105, 299–312.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

A N TI SO CI A L BEH AV I O U R

Est imat es of herit abilit y f or ant isocial behaviour f rom recent research in quant it at ive genet ics clust er around 0.50. The most reliable est imat es come f rom cont emporary st udies in t he Net herlands, Brit ain, Norw ay, Sw eden, Aust ralia and t he US, because t hese st udies examine large, represent at ive samples using sophist icat ed quant it at ive modelling t echniques. A complement ary met a-analysis of 51 t w in and adopt ion st udies yielded an est imat e of herit abilit y of 0.41 f or t he genet ic inf luence on ant isocial behaviour.5 Est imat es of herit abilit y below 0.20 t end t o emerge f rom st udies w it h unusual design f eat ures; f or example, observat ional measures, small sample sizes, very w ide age ranges, small groups of girls, or adult s being asked t o report childhood sympt oms ret rospect ively. Similarly, some, but not all, st udies yielding est imat es above 0.70 have non-opt imal designs, such as small sample sizes or adult s being asked t o report t heir childhood sympt oms ret rospect ively.

EV I D EN CE:

9.9

TH E

Antisocial behaviour

O F

Current findings: quantitative genetics

REV I EW

The advant ages of t he principle of cont inuous dimensional measures do not apply only t o research in behavioural genet ics. Rat her, measures of ant isocial behaviour t hat sample a variet y of behaviours are more usef ul in ot her t ypes of research as w ell. For example, longit udinal research show s t hat t he variet y of diff erent ant isocial act s a child has exhibit ed is t he single best predict or of his or her adult out come.4 There is t heref ore a grow ing consensus t hat measures of ant isocial behaviour should gat her dat a about a large number of diff erent behaviours covering a w ide range of ant isocial severit y, and should include a period of observat ion t hat allow s enough t ime f or research part icipant s t o exhibit t he behaviours.

9

9.8

CH A PTER

of conduct disorder, or not ? Does he or she have a diagnosis of ant isocial personalit y disorder, or not ? Assigning a person t o such cat egories is a mat t er of deciding t hat his or her behaviour has surpassed some cut -off point along a cont inuous measure of ant isocial behaviours. The cut -off point s are more arbit rary t han based on evidence. Unreliable assignment arises f requent ly because individuals’ scores f all just above or below cut -off point s. Quant it at ive genet ic t heory, psychomet ric t heory and accumulat ed research f indings suggest t hat a t ruer, and more reliable, measure of individual diff erences in ant isocial behaviour is obt ained w hen t he nat ural cont inuum is not arbit rarily cut int o cat egories. For t his reason, w e consider ant isocial behaviour in t his Report as a t rait t hat is normally dist ribut ed and t heref ore able t o be measured as part of variat ion in t he normal range.

9.10 The sizes of est imat es of herit abilit y vary somew hat across diff erent t ypes of measures of ant isocial involvement . Overall, t his variat ion appears t o be syst emat ic. It ref lect s t he f act t hat (all ot her aspect s of met hodology being equal) higher est imat es of herit abilit y are obt ained f rom st udies using measures t hat sample t he most diff erent t ypes of ant isocial behaviours. M easures t hat sample many behaviours yield more accurat e est imat es because t heir scores are less cont aminat ed w it h error, and also because t hey are more sensit ive t o

4

Robins, L. N. (1978). St urdy childhood predict ors of ant isocial behaviour: replicat ions f rom longit udinal st udies. Psychol. M ed. 8, 611–22.

5

Rhee, S. H. & Waldman, I. D. (2002). Genet ic and environment al inf luences on ant isocial behavior: a met a-analysis of t w in and adopt ion st udies. Psychol. Bull. 128, 490–529.

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t he f ull range of behaviour in t he populat ion. The low est est imat es of herit abilit y emerge f rom observat ional measures, w hich sample only a narrow t ype of behaviour such as hit t ing a doll or arguing w it h a parent , over brief spans of t ime, usually minut es. The next low est est imat es emerge f rom measures of off icial off ending in juveniles, w hich also sample a narrow range of behaviour, namely illegal behaviour, w hich is seldom det ect ed. Few er t han half of juveniles w ho off end are arrest ed, and of t hose arrest ed 75% are arrest ed only once or t w ice. M edium est imat es of herit abilit y t end t o emerge f rom measures of self -report ed off ending, sympt oms of conduct disorder and off icial off ending in adult s, all of w hich t end t o aggregat e across a moderat ely w ide sample of behaviours and moderat ely long periods of ascert ainment . 9.11 The largest est imat es of herit abilit y t end t o emerge f rom st udies using measures able t o array individuals along a cont inuum f rom non-ant isocial t o severely and persist ent ly ant isocial. These are st udies using ot her-report ed delinquent or aggressive behaviours (such as t he Child Behaviour Check List (CBCL) ext ernalising scale), and self -report ed personalit y t rait s (such as t he M PQ aggression scale). These st udies t end t o include a very large number of it ems inquiring about a variet y of ant isocial at t it udes and behaviours. Some of t hese it ems, such as robbery, are exhibit ed rarely by people, but ot hers, such as enjoying violent f ilms, are exhibit ed commonly. As a result , t he inst rument s are sensit ive t o populat ion variat ion in t he severit y of ant isocial behaviour.6 Overall, t he dist ribut ion of more t han 100 est imat es of herit abilit y f rom recent papers approximat es a bell-shaped normal curve. This dist ribut ion is t o be expect ed f rom a sample of more t han 100 imperf ect est imat es of a t rue eff ect t hat equals 50% in nat ure. 9.12 As w ell as t he possibilit y t hat genes inf luence ant isocial behaviour, it is also possible t hat ant isocial experience can inf luence how genes are dist ribut ed in t he populat ion. This is an implicat ion of t he f inding t hat men and w omen mat e on t he basis of similarit y bet w een t he part ners’ ant isocial behaviour (t his is called assort at ive mat ing), and t hat couples in w hich bot h people exhibit ant isocial behaviour t end t o have more children t han t he norm.7 Assort at ive mat ing on a genet ically-inf luenced phenot ype, such as ant isocial behaviour has consequences f or genet ic variat ion in t he populat ion. Because people f orm unions w it h ot her people like t hemselves, t he result is t hat f amilies diff er more f rom each ot her on average t han t hey w ould if people mat ed randomly. If successive generat ions mat e assort at ively, genes relevant t o t he phenot ype w ill become concent rat ed w it hin f amilies. Consider height as an example. Whole f amilies clearly diff er f rom ot her f amilies in t erms of height , yet f amilies are made up of persons w ho are similar in height . Part of t he explanat ion f or t his phenomenon is likely t o lie in t he posit ive assort at ive mat ing t hat occurs f or t his t rait .

9 2

6

A st udy of 14,500 Danish adopt ee f amilies provides a good example of t he import ance of measures t hat sample diff erent act s along a dimension t o improve sensit ivit y t o f eat ures of ant isocial behaviour such as severit y, f requency and persist ence (M ednick, S. A., Gabrielli, W. F. & Hut chings, B. (1984). Genet ic f act ors in criminal behaviour: evidence f rom an adopt ion cohort . Science 224, 891–3). When adopt ee f amily members w ere classif ied simply as ‘not convict ed’ or ‘convict ed’ (a legal st at us applying t o nearly one quart er of Danish males), t he est imat e of herit abilit y w as modest . How ever, w hen t he number of convict ions in an individual’s lif e-t ime f rom age 15 t o 50 w as considered, st ronger est imat es of herit abilit y emerged f or individuals w ho had repeat edly been convict ed on many successive court dat es, presumably ref lect ing w hat criminologist s call a ‘crime career’.

7

See f or example Farringt on, D. P., Barnes, G. C. & Lambert , S. (1996). The concent rat ion of off ending in f amilies. Leg. Criminol. Psychol. 1, 47–63; Row e, D. C. & Farringt on. D. P. (1997). The f amilial t ransmission of criminal convict ions. Criminology 35, 177–201; Farringt on, D. P., Jolliff e, D., Loeber, R., St out hamer-Loeber, M . & Kalb, L. (2001). The concent rat ion of off enders in f amilies, and f amily criminalit y in t he predict ion of boys’ delinquency. J. Adolescence 24, 579–96; Kreuger, R. F., M off it t , T. E., Caspi, A., Bleske, A. & Silva, P. A. (1998). Assort at ive mat ing f or ant isocial behaviour: development and met hodological implicat ions. Behav. Genet . 28, 173–86.

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TH E EV I D EN CE: A N TI SO CI A L BEH AV I O U R

9.16 The ant idot e t o st udying convict ions is t o use measures of violence t hat inquire about violent behaviours t hat have physical diff erences and cover a range of severit y (f ight ing, hurt ing animals, robbery, hit t ing, aggravat ed assault using a w eapon, gang-f ight ing, rape and domest ic abuse). It is also helpf ul t o use a report ing period long enough f or research part icipant s w ho are violent ly inclined t o exhibit t hese relat ively rare behaviours. This approach w as used in t w o st udies of self -report ed violence in t w ins and siblings, w hich yielded signif icant est imat es of herit abilit y.10

O F

9.15 Tw o main diff icult ies arise in t he st udy of individual diff erences in off icial records of convict ion f or violent crime. First , even in t he largest samples, off icial convict ions f or violent crime occur at very low rat es. Inconsist ent f indings arise f rom such low indicat ors, because t hey cannot be reliably aggregat ed. Secondly, cont rary t o popular assumpt ion, off enders designat ed ‘violent ’ by virt ue of court convict ion are not necessarily t he most serious, persist ent criminals at t he ant isocial ext reme. To illust rat e, st udies of murderers reveal t hat approximat ely half have lengt hy hist ories of repeat ed assault s, rapes, robberies and ot her off ence t ypes, but t he ot her half have commit t ed a single ext reme act af t er a lif et ime f ree f rom crime. This indicat es t hat t he most serious of violent off ences, homicide, as a legally const ruct ed st at us, capt ures individuals likely t o be quit e het erogeneous in t heir genet ic disposit ions. Low base rat es and het erogeneous part icipant s may explain w hy st udies using convict ion dat a have f ound no herit abilit y f or violence.

REV I EW

9.14 Public debat e about t he implicat ions of herit abilit y f or criminal responsibilit y of t en f ocuses on violent crime. Findings about genet ic eff ect s on violence are rare and inconsist ent . Three st udies report evidence of a value of zero f or t he herit abilit y f or violence,8 w hereas t hree st udies report evidence t hat herit abilit y f or violence is about t he same as f or non-violent ant isocial behaviour (0.50).9

9

Violence

CH A PTER

9.13 Anot her import ant insight f rom research in behavioural genet ics is t hat w hile genes inf luence t endencies t ow ards ant isocial personalit y and ant isocial behaviour, t hey have relat ively lit t le inf luence on t he probabilit y of becoming off icially designat ed as a delinquent at any part icular court appearance. The designat ion of ‘delinquent ’ is a charact erist ic inf luenced by t he behaviour of co-off enders, police, parent s, law yers and judges, not merely by t he behaviour of t he young person.

9.17 Researchers in behavioural genet ics usually do not single out violence f or separat e analysis. Researchers are dissuaded f rom doing so by t he st rong psychomet ric evidence t hat ant isocial behaviour is a unif ied const ruct and t heref ore a separat e research f ocus on violence is not w arrant ed. M ost st udies of t he st ruct ure of ant isocial behaviour have

8

Bohman, M ., Cloninger, R., Sigvardsson, S. & von Knoring, A. L. (1982). Predisposit ion t o pet t y criminalit y in Sw edish adopt ees. I. Genet ic and environment al het erogeneit y. Arch. Gen. Psychiat r. 39, 1233–41; M ednick, S. A., Gabrielli, W. F. & Hut chings, B. (1984). Genet ic f act ors in criminal behaviour: evidence f rom an adopt ion cohort . Science 224, 891–3; Sigvardsson, S., Cloninger, C. R., Bohman, M . & von Korring, A. (1982). Predisposit ion t o pet t y criminalit y in Sw edish adopt ees. III. Sex diff erences and validat ion of t he male t ypology. Arch. Gen. Psychiat r. 39, 1248–53.

9

Herit abilit y is report ed as 50% in Cloninger, C. R. & Got t esman, I. I. Genet ic and environment al f act ors in ant isocial behaviour disorders. In M ednick, S. A., M off it t , T. E. & St ack, S. A., edit ors. (1987). The Causes of Crime: New Biological Approaches. Cambridge: Cambridge Universit y Press. pp. 92–109; 32% in Row e, D. C., Almeida, D. M . Jacobson, K. C. (1999). School cont ext and genet ic inf luences on aggression in adolescence. Psychol. Sci. 10, 277–80; 55% in Rusht on, J. P. (1996). Self -report delinquency and violence in adult t w ins. Psychiat r. Genet . 6, 87–9.

10

Row e, D. C., Almeida, D. M . & Jacobson, K. C. (1999). School cont ext and genet ic inf luences on aggression in adolescence. Psychol. Sci. 10, 277–80; Rusht on, J. P. (1996). Self -report delinquency and violence in adult t w ins. Psychiat r. Genet . 6, 87–9.

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suggest ed t hat it ems measuring physical aggression belong t oget her w it h it ems assessing st ealing, lying, f raud, vice, reckless irresponsibilit y and ot her f orms of ant isocial behaviour.11 9.19 M any st udies in behavioural genet ics have examined measures know n t o be st rong, specif ic predict ors of physical violence. For example, many have used t he M PQ aggression scale and have report ed st rong est imat es of herit abilit y. The M PQ aggression scale measures at t it udes, values, and belief s t hat are consist ent w it h approval of t he use of physical violence.12 Longit udinal research show s t hat t he M PQ aggression scale empirically predict s f ut ure convict ion f or violent crime.13 9.20 Overall, t he quest ion of genet ic inf luences f or violent crime has not int erest ed researchers in behavioural genet ics as much as it has t he general public. As a result , t he evidence base is not suff icient t o answ er t he quest ion decisively. How ever, t here is good evidence of herit abilit y f or ant isocial t rait s and behaviours associat ed w it h risk f or engaging in violent crime, and t his suggest s t hat herit able liabilit y f or violence is a reasonable hypot hesis. An area overlooked by research in behavioural genet ics is violence w it hin relat ionships, a t ype of violence f or w hich t here are reliable aggregat e measurement t ools.

Sex differences 9.21 Dif f erences bet w een t he sexes in herit abilit y of ant isocial behaviour may exist , but are small. It is unclear as yet w het her t hese small dif f erences should be int erpret ed as subst ant ive, or as art ef act s of sex dif f erences in measurement . On balance, t he result s of model t est s in large samples suggest t hat est imat es of herit abilit y may be slight ly higher among males t han f emales, but t hat sex-specif ic models of herit abilit y cannot be just if ied.14 9.22 Est imat es of herit abilit y may be slight ly smaller f or f emales because measurement s of ant isocial behaviour among f emales represent less of t he f ull range of ant isocial severit y, relat ive t o measurement s among males. The ant isocial behaviour perf ormed by f emales is less serious and less f requent t han t hat of males, and f emales part icipat e in ant isocial act ivit ies f or a much short er period of t he lif e course t han males.15 The relat ive rarit y and brevit y of f emales’ ant isocial behaviour makes it dif f icult t o obt ain st rong aggregat e measures of it , and t his may inf luence est imat es of herit abilit y dow nw ards f or f emales.

9 4

11

M off it t , T. E., Krueger, R. F., Caspi, A. & Fagan, R. W. (2000). Part ner abuse and general crime: How are t hey t he same? How are t hey diff erent ? Criminology 38, 201–35; Blumst ein, A., Cohen, J., Das, S. & M oit ra, S. (1988). Specializat ion and seriousness during adult criminal careers. J. Quan. Criminol. 4, 303–45; Farringt on, D., Snyder, H. & Finnegan, T. (1988). Specializat ion in juvenile court careers. Criminology 26, 461–85.

12

Do not be misled by t he names of measures; most scales labelled ‘aggression’, including t he M PQ, do not measure physical aggression.

13

M off it t , T. E., Krueger, R. F., Caspi, A. & Fagan, R. W. (2000). Part ner abuse and general crime: How are t hey t he same? How are t hey diff erent ? Criminology 38, 201–35.

14

Gjone, H. & St evenson, J. (1997). The associat ion bet w een int ernalizing and ext ernalizing behaviour in childhood and early adolescence: Genet ic or environment al common inf luences? J. Abnorm. Child Psychol. 25, 277–86; Eaves, L. et al. (1997). Genet ics and development al psychopat hology: 2. The main eff ect s of genes and environment on behavioural problems in t he Virginia st udy of adolescent behavioural development . J. Child Psychol. Psychiat r. 38, 965–80; Taylor, J., M cGue, M ., Iacono, W. G. & Lykken, D. T. (2000). A behavioural genet ic analysis of t he relat ionship bet w een t he socializat ion scale and self -report ed delinquency. J. Pers. 68, 29–50; Finkle, D. & M cGue, M . (1997). Sex diff erences and nonaddit ivit y in t he herit abilit y on t he M ult idimensional Personalit y Quest ionnaire scales. J. Pers. Soc. Psychol. 72, 929–38.

15

M off it t , T. E., Caspi, A., Rut t er, M . & Silva, P. A. (2001). Sex Diff erences in Ant isocial Behaviour: Conduct Disorder, Delinquency, and Violence in t he Dunedin Longit udinal St udy. Cambridge: Cambridge Universit y Press.

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O F TH E EV I D EN CE: A N TI SO CI A L BEH AV I O U R

9.25 In August 2002, a st udy w as published w hich invest igat ed t he link bet w een M AOA and ant isocial behaviour in a group of 500 male children.17 The st udy examined t he genot ypes of t he boys and ident if ied a variant in t he M AOA gene t hat w as associat ed w it h high levels of M AOA act ivit y in t he brain, and anot her t hat w as associat ed w it h low levels. The researchers f ound t hat children w it h t he genot ype conf erring low levels of M AOA act ivit y w ere signif icant ly more likely t o grow up t o exhibit ant isocial behaviour t han t hose w it h high levels, but only if t hey w ere also malt reat ed and abused as children. In ot her w ords, it w as t he int eract ion bet w een t he genet ic variant and t he environment t o w hich t he children w ere exposed t hat w as import ant . Children w it h low levels of M AOA act ivit y w ho w ere not malt reat ed did not display ant isocial behaviour. Nor did children w it h high levels of M AOA act ivit y w ho w ere malt reat ed. The researchers st at ed t hat t heir f indings ‘may part ly explain w hy some vict ims of malt reat ment grow up t o vict imise ot hers’. This research is part icularly int erest ing because it demonst rat es t he connect ion bet w een genet ic and environment al inf luences on behaviour. We discuss it s implicat ions f urt her in paragraphs 14.34 – 14.44 in t he cont ext of predict ing f ut ure criminal and ant isocial behaviour.

REV I EW

9.24 There is one st udy t hat has claimed t o f ind an associat ion bet w een a genet ic variant and f orms of ant isocial behaviour. In t he 1980s, researchers became int erest ed in a part icular f amily in t he Net herlands. M any of t he male members of t he f amily behaved in a not ably violent and aggressive manner, and a considerable number had been involved in serious crime including rape and arson. Analysis of t he f amily pedigree led researchers t o look f or a gene on t he X chromosome t hat might be linked t o t his t endency in t he men. They f ocused on a gene responsible f or producing a prot ein called monoamine oxidase A (M AOA), involved in regulat ing t he met abolism of serot onin in t he brain. The male members of t he f amily w ho engaged in aggressive behaviour w ere f ound t o have abnormally low levels of M AOA in t heir bodies, and a def ect in t he gene w as ident if ied in t hese men in 1993.16 They w ere also f ound t o have low er t han average IQs of around 80.

9

9.23 St rong est imat es of herit abilit y f or a behavioural t rait are generally t aken t o recommend f urt her genet ic research at t he molecular level, t o ident if y specif ic genes associat ed w it h t he t rait , and t o ascert ain t heir f unct ions in relat ion t o t he brain. Ant isocial behaviour is not current ly a high priorit y f or research in molecular genet ics, because it is not as st rongly herit able as disorders such as aut ism or schizophrenia. Nonet heless, molecular genet ic research int o ant isocial behaviour w ill be pursued because ant isocial behaviour f orms part of a syndrome alongside t w o disorders t hat are current ly of great int erest in molecular genet ics: At t ent ion Def icit Hyperact ivit y Disorder and subst ance-dependence. Ant isocial behaviour is a complex disorder, quant it at ively dist ribut ed in t he populat ion, and as a result , ant isocial behaviour must be inf luenced by many genes of small eff ect .

CH A PTER

Current findings: molecular genetics

Current findings: research involving animals 9.26 The relevance of animal models of aggression f or human ant isocial behaviour has not yet been f ully est ablished. How ever, rodent s off er t he clear advant age of experiment al manipulat ion t o t est eff ect s of specif ic genes on aggression. Genet ic research int o

16

Brunner, H. G., Nelen, M ., Breakef ield, X. O., Ropers, H. H. & van Oost , B. A. (1993). Abnormal behavior associat ed w it h a point mut at ion in t he st ruct ural gene f or monoamine oxidase A. Science 262, 578–80.

17

Caspi, A. et al. (2002). Role of genot ype in t he cycle of violence in malt reat ed children. Science 297, 851-4.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

aggression in animals (such as select ive breeding of highly aggressive mouse st rains, or st udies of enhanced aggression in mice w it h ‘knockout ’ manipulat ions of t he genome) is proceeding rapidly, w hich should lead t o f indings in molecular genet ics in t he relat ed area of human ant isocial behaviour.18 9.27 One example of such a st udy w as report ed in M ay 2002, w hich claimed t o have ident if ied a genet ic mut at ion t hat caused violent behaviour in mice.19 The mut at ion, nicknamed ‘f ierce’, has a range of eff ect s in mice including ext remely violent behaviour t ow ards ot her mice, signif icant brain def ect s and physical diff erences such as decreased size, body f at and eye abnormalit ies.20 A count erpart of t he gene does exist in humans, but it s precise f unct ion is not know n.

Future directions for research 9.28 Quant it at ive research t echniques are usef ul f or revealing t he cont ribut ion of environment al f act ors t o ant isocial out comes in humans. This is a priorit y f or f ut ure research because it may indicat e t he possibilit y of st rat egies f or prevent ion. Researchers in behavioural genet ics are beginning t o include in t heir research, measures of t he environment al f act ors t hat are t hought t o cont ribut e t o ant isocial behaviour, such as t he malt reat ment of children, povert y and inconsist ent discipline. St udies w ill hope t o ascert ain how t he environment s of young people int eract w it h t heir genet ic vulnerabilit ies, t o exacerbat e or prot ect against t heir risk f or ant isocial behaviour. Longit udinal research w ill f ollow samples of t w ins and adopt ees as t hey age, t o explore t he changing balance bet w een genet ic and environment al f act ors t hat inf luence ant isocial behaviour over t he course of an individual’s lif e. Because ‘crime’ it self is not inherit ed, researchers are w orking t o invest igat e w hich f eat ures of personalit y and cognit ive f unct ion may be associat ed w it h ant isocial behaviour. Wit h regard t o molecular research t echniques, research int o M AOArelat ed genot ypes is likely t o cont inue (see paragraphs 9.24–9.25), along w it h research int o ot her genes ident if ied in research involving animals, and genes know n t o have f unct ional signif icance in t he brain. Import ant ly, quant it at ive and molecular w ork is converging on t he possibilit y t hat genes act t o augment t he resist ance of young people t o environment al f act ors t hat w ould ot herw ise increase t he likelihood of ant isocial behaviour.

9 6

18

For a review see M axson, S. C. Genet ic inf luences on aggressive behavior. In Pf aff , D. W., Berret t ini, W. H., Toh. H. J. & M axson, S. C., edit ors. (2000). Genet ic Inf luences on Neural Behavioural Funct ions. New York: CRC Press. pp. 405–15.

19

Young, K. A. et al. (2002). Fierce: a new mouse delet ion of Nr2e1; violent behaviour and ocular abnormalit ies are background-dependent . Behav. Brain Res. 132, 145–58.

20

An int erest ing observat ion about t his st udy is t hat t he researchers did not set out t o ident if y genes t hat inf luenced violent behaviour – t hey w ere st udying reproduct ion. This illust rat es t he point made in Chapt ers 3 and 4 t hat f indings relat ed t o behavioural t rait s are likely t o emerge as a result of genet ic research int o disorders, making it diff icult t o prevent t his kind of know ledge f rom being discovered.

Chapter Review of the evidence: sexual orientation

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O F TH E EV I D EN CE: SEX U A L O RI EN TATI O N

10.2 There remains considerable cont roversy about w het her sexual orient at ion is a mat t er of choice and w het her it is possible t o change one’s sexual orient at ion. A recent Gallup poll conduct ed in June 2001 on Americans’ at t it udes t ow ards homosexualit y asked ‘In your view, is homosexualit y somet hing a person is born w it h or is homosexualit y due t o ot her f act ors such as upbringing or environment ?’ 40% of respondent s said t hat it w as somet hing a person w as born w it h, w hile 39% f elt t hat it w as t he result of environment al f act ors. This w as t he f irst t ime t hat opinion had been equally split since t he f irst poll in 1977, at w hich t ime t he respect ive f igures w ere 13% and 56% . During t he period 1977–2001, t here w as also a gradual increase in adherence t o t he belief t hat homosexualit y is an accept able alt ernat ive lif est yle, t hough approximat ely half of t hose quest ioned in 2001 st ill t hought it w as not . Various polls have show n t hat people w ho believe homosexual orient at ion cannot be changed, is biologically based or is not a choice are more likely also t o believe t hat t here should not be social or criminal sanct ions against homosexual behaviour.3

REV I EW

10.1 There has alw ays been considerable int erest in biological explanat ions of homosexualit y, as in ot her aspect s of human behaviour. Unt il t he 1970s, homosexualit y w as classif ied as a ment al disorder in many West ern count ries, w hich meant t hat much research w as aimed at developing ‘cures’ f or t he ‘disease’.1 Today, t he vast majorit y of count ries do not classif y homosexualit y as a disease. Nevert heless, at t it udes t ow ards homosexuals are of t en negat ive, host ile and discriminat ory. Homosexual behaviour remains illegal in over 40 count ries across Af rica, Asia, Europe, t he M iddle East and t he Americas, and in some, it is punishable by deat h.2 Even in t hose count ries in w hich homosexualit y is not illegal, it is of t en t he case t hat homosexual couples are not aw arded t he same legal right s and recognit ion as het erosexual couples.

1 0

Background

CH A PTER

Review of t he evidence: sexual orient at ion

Trait measurement and definition 10.3 The scale most commonly used t o measure sexual orient at ion is t he Kinsey Scale, w hich w as developed in 1948. This measures sexual behaviour and f ant asies on a cont inuum f rom ‘exclusively het erosexual’ t o ‘exclusively homosexual’ (see Box 10.1). Individuals obt ain scores of bet w een zero and six, w it h zero and one usually classed as het erosexual and f ive and six classed as homosexual, f or t he purposes of t he research. There is an addit ional cat egory f or individuals w it h no sexual cont act s or react ions. Ot her measures, such as t he

1

M ost count ries use one of t w o classif icat ion and diagnost ic syst ems f or psychiat ric illness: t he Diagnost ic St at ist ical M anual f or M ent al Disorders (DSM ), published by t he American Psychiat ric Associat ion, or t he Int ernat ional Classif icat ions of Diseases, M ent al Disorders Sect ion (ICD). Homosexualit y w as removed f rom t he DSM in 1973. A new ‘disorder’ of ego-dyst onic homosexualit y w as included in t he 3rd edit ion in 1980 but w as removed six years lat er af t er considerable crit icism. Homosexualit y w as included as a psychiat ric disorder in t he ICD unt il t he publicat ion of it s 10t h edit ion in 1993.

2

The Int ernat ional Lesbian and Gay Associat ion. (Sept ember 1999). Int ernat ional Lesbian and Gay Associat ion World Legal Survey 1999. ht t p://w w w.ilga.org/Inf ormat ion/Legal_survey/ilga_w orld_legal_survey% 20int roduct ion.ht m. (9 August 2002).

3

See, f or example, Whit ley, B. E., Jr. (1990). The relat ionship of het erosexuals' at t ribut ions f or t he causes of homosexualit y t o at t it udes t ow ard lesbians and gay men. Pers. Soc. Psychol. B. 16, 369–77; Piskur, J. & Degelman, D. (1992). Eff ect of reading a summary of research about biological bases of homosexual orient at ion on at t it udes t ow ard homosexuals. Psychol. Report . 71, 1219–25.

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Klein Sexual Orient at ion Grid, include a w ider range of variables such as sexual at t ract ion, self -ident if icat ion, emot ional pref erences, social pref erences and lif est yle. How ever, t hese more det ailed measures complicat e t he analysis of dat a and are t hus used less commonly.

Box 10.1: The Kinsey scale of sexual orientation 0 1 2 3 4 5 6

Exclusively het erosexual Predominant ly het erosexual/only incident ally homosexual Predominant ly het erosexual but more t han incident ally homosexual Equally het erosexual and homosexual Predominant ly homosexual but more t han incident ally het erosexual Predominant ly homosexual/only incident ally het erosexual Exclusively homosexual

10.4 Scales such as t he Kinsey Scale are designed f or self -report ing. In many st udies of t he biological basis of sexual orient at ion, dat a about f amily members and relat ives are also collect ed. Of t en t his is done by administ ering quest ionnaires or int erview s, but in some cases, research part icipant s are asked t o est imat e t he sexual orient at ion of t heir relat ives based on t heir ow n experience of t hem. The correlat ion of self -report s by relat ives and report s about t heir relat ives by research part icipant s is usually high, but does leave open t he possibilit y t hat some individuals w ill be assigned t o t he w rong group. 10.5 There are numerous w ays in w hich biological f eat ures could, in t heory, inf luence sexual orient at ion. For example, t hey could aff ect sexual orient at ion direct ly by inf luencing t he physical development of t he brain. Alt ernat ively, t hey could operat e indirect ly by aff ect ing personalit y and t emperament , w hich in t urn could aff ect an individual’s development and int eract ion w it h environment al f act ors. These biological inf luences need not be genet ic; t hey could, f or example, be chemical or hormonal. How ever, it should be remembered t hat t he cont rol of hormones is largely mediat ed t hrough genet ic f act ors. This sect ion summarises t he result s of key research int o genet ic and ot her biological inf luences on human sexual orient at ion.

Current findings: quantitative genetics

Families 10.6 The rat e of homosexual orient at ion in t he general populat ion has been variously est imat ed bet w een 2% and 10% depending on t he crit eria used, w it h 4–5% being t he most common est imat e f or males, and around 2–4% f or f emales.4 Calculat ions of t he rat e of homosexualit y are made diff icult by t he f act t hat some individuals may not w ish t o divulge t heir sexual orient at ion t o a t hird part y, and because of t he various w ays in w hich sexual orient at ion can be def ined and measured. 10.7 A number of st udies have calculat ed t he rat e of homosexual orient at ion among siblings w here one sibling is homosexual.5 M ost st udies show t hat t he rat e of homosexualit y among

1 0 0

4

See f or example Le Vay, S. (1993). The Sexual Brain. Cambridge, M A: M IT. p.108. The Brit ish Nat ional Survey of Sexual At t it udes and Lif est yles (2000) f ound rat es of up t o 8.5% in males aged 26–44.

5

Bailey, J. M . & Pillard, R.C. (1995). Genet ics of human sexual orient at ion. An. Rev. Sex Res. 6, 126–50.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

O F TH E EV I D EN CE: SEX U A L O RI EN TATI O N

M ale homosexualit y 10.9 Bailey and Pillard f ound t hat 52% of t he M Z co-t w ins of male homosexual t w ins w ere also homosexual or bisexual.7 For DZ male t w ins, t his f ell t o 22% , w hich suggest s t hat genet ic f act ors may be inf luent ial. The researchers est imat ed t he herit abilit y of male homosexualit y and bisexualit y t o be bet w een 0.31 and 0.74. Analysis of t he various models of t he possible inf luences on sexual orient at ion developed by t he researchers show ed t hat genet ic inf luences w ere alw ays st at ist ically signif icant , w hile non-shared environment al inf luences w ere somet imes signif icant , and shared environment al inf luences w ere never signif icant .

REV I EW

10.8 In recent years, t hree st udies have examined t he concordance rat es f or sexual orient at ion among monozygot ic (M Z) and dizygot ic (DZ) t w ins and t heir biological and adopt ive siblings. These st udies show t hat t here is a signif icant genet ic inf luence on sexual orient at ion. How ever, alt hough all t he st udies show t he same general t rend, t here is considerable variat ion in t he levels of concordance ident if ied. This may be explained by t he sampling met hods used. The st udies t hat f ound t he highest concordance rat es w ere t hose obt ained in samples recruit ed t hrough homophile publicat ions rat her t han select ing part icipant s f rom t he general populat ion, w hich may have led t o biased samples. Furt her, an obvious point , but one w ort h making, is t hat even t he highest concordance rat es f ound f or ident ical t w ins are in t he region of 50% , w hich indicat es t hat environment al f act ors are at least as import ant as genet ic f act ors in explaining variat ion in sexual orient at ion.

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Tw ins and adopted siblings

CH A PTER

t he brot hers of a male homosexual appears t o be around 9% , t hough one st udy f ound a much higher rat e of 22% . The rat e of homosexualit y among t he sist ers of a male homosexual appears t o be around 5% . Findings of t he rat e of homosexualit y among t he sist ers of a homosexual f emale range f rom 6% t o 25% .6 The rat e of homosexualit y among t he brot hers of a homosexual f emale appears t o be around 10% . These result s indicat e t hat homosexual males may be more likely t o have homosexual brot hers t han homosexual sist ers. Homosexual f emales may be more likely t o have homosexual sist ers t han homosexual brot hers. This suggest s t hat t he f act ors inf luencing homosexual orient at ion may be diff erent f or males t han f or f emales.

10.10 The st udy also f ound t hat 11% of t he adopt ed brot hers of homosexual or bisexual male t w ins w ere also homosexual or bisexual, and t hat 9% of non-t w in biologically-relat ed brot hers of homosexual or bisexual male t w ins w ere homosexual or bisexual. If t he rat e of homosexualit y in t he general populat ion is est imat ed at around 4% ,8 t he higher rat e of concordance f or homosexualit y in adopt ed siblings t han in t he general populat ion point s t o a subst ant ial environment al cont ribut ion. How ever, since t here is no agreed rat e of homosexual orient at ion in t he populat ion, and since t his research assessed rat es of homosexualit y and bisexualit y t oget her, t his conclusion must be t reat ed w it h caut ion.

6

Pillard, R. C. & Weinrich, J. D. (1986). Evidence of f amilial nat ure of male homosexualit y. Arch. Gen. Psychiat . 43, 808–12.

7

Bailey, J. M . & Pillard, R. C. (1991). A genet ic st udy of male sexual orient at ion. Arch. Gen. Psychiat . 48, 1089–96. The researchers def ined a score of great er t han 1 on t he Kinsey scale as homosexual or bisexual, t reat ing homosexualit y and bisexualit y as one group f or t heir research.

8

Gebhard, P. H. Incidence of overt homosexualit y in t he Unit ed St at es and West ern Europe. In Livingood, J. M ., edit or. (1972). NIM H Task Force on Homosexualit y: Final Report and Background Papers. Rockville, M D: Nat ional Inst it ut e of M ent al Healt h. Ot her est imat es range f rom 2 t o 10% . Female homosexualit y is less prevalent , perhaps about half as common as male homosexualit y.

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10.11 It is int erest ing t o not e t he discrepancy bet w een concordance rat es bet w een DZ t w ins (22% ), and t hose f or DZ t w ins compared t o t heir non-t w in brot hers (9% ). Since DZ t w ins and t heir non-t w in siblings are genet ically similar t o t he same degree, t he diff erence in concordance point s t o an import ant environment al f act or t hat makes non-ident ical t w ins more similar t han siblings. Bailey and Pillard acknow ledge t his possibilit y but observe t hat anot her st udy f ound t he concordance rat es t o be more similar and not e t hat t heir result s could be explained by sampling f luct uat ions. Anot her int erest ing f eat ure of t heir st udy is t hat non-t w in biological brot hers show t he low est rat es of concordance, low er even t han adopt ed siblings, w hich seems, at f irst impression, t o cont radict a biological explanat ion. It is possible t hat t his f inding is t he result of ascert ainment bias, or some ot her f eat ure of t he research: in any case, it st rongly suggest s t hat f urt her st udies are needed bef ore f irm conclusions can be made. 10.12 M ore recent ly, Kendler et al conduct ed a st udy t hat used a random sample of approximat ely 3,000 people. The researchers f ound a concordance rat e of 32% f or nonhet erosexual orient at ion in M Z t w ins.9 For DZ t w ins of t he same sex, t he chance of t he second t w in also being homosexual or bisexual f ell t o 13% . The researchers est imat ed t hat t he herit abilit y of male sexual orient at ion w as bet w een 0.28 and 0.65. Female homosexualit y 10.13 Bailey et al f ound t hat 48% of M Z co-t w ins of f emale homosexual t w ins w ere also homosexual.10 For DZ f emale t w ins, t he chance of t he second t w in also being homosexual f ell t o 16% ; 6% of adopt ive sist ers of f emale homosexual t w ins w ere also homosexual. The homosexual f emale t w ins st udied report ed concordance rat es of 14% w it h t heir non-t w in sist ers. The researchers calculat ed t he herit abilit y of sexual orient at ion t o be bet w een 0.27 and 0.76.

Current findings: molecular genetics 10.14 In t he light of t he evidence f rom f amily, t w in and adopt ive st udies w hich suggest s t hat genet ic f act ors, along w it h environment al f act ors, may inf luence sexual orient at ion t o some degree, at t empt s have been made t o ident if y t he part icular genes involved. The most w ell-know n research is t hat of Dean Hamer, w ho received considerable publicit y in t he early 1990s and w as w idely report ed as having discovered t he ‘gay gene’. Hamer st udied 40 pairs of homosexual brot hers w ho all had f amily hist ories t hat indicat ed a high rat e of homosexualit y on t he mot her’s side.11 He int erpret ed t his t o mean t hat a genet ic inf luence on sexual orient at ion might be f ound on t he X chromosome in t hese f amilies. In 33 of t he 40 sibling pairs, he ident if ied signif icant similarit ies in t he genet ic markers in a part icular region of t he X chromosome called Xq28, w hich cont ains 4 million base pairs and approximat ely one hundred genes. Since male children only inherit one X chromosome f rom t heir mot hers, w ho have t w o X chromosomes, t he probabilit y of bot h brot hers in a sibling pair having inherit ed t he same part of t he X chromosome is only 50% . Thus, t he f inding of 82% of sibling pairs w it h shared DNA in t his region w as f ound t o be signif icant .

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9

Kendler, K. S., Thornt on, L. M ., Gilman, S. E. & Kessler, R. C. (2000). Sexual Orient at ion in a US Nat ional Sample of Tw in and Nont w in sibling pairs. Am. J. Psychiat . 157, 1843–6.

10

Bailey, J. M ., Pillard, R. C., Neale, M . C. & Agyei, Y. (1993). Herit able f act ors inf luence f emale sexual orient at ion. Arch. Gen. Psychiat . 50, 217–23.

11

Hamer, D. H., Hu, S., M agnuson, V. L., Hu, N. & Pat t at ucci, A. M . L. (1993). A linkage bet w een DNA markers on t he X chromosome and male sexual orient at ion. Science 261, 321–7.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

TH E EV I D EN CE: SEX U A L O RI EN TATI O N

10.18 Homosexual behaviour in animals has been w idely report ed,14 but research int o t he genet ic basis of such behaviour is less common. One st udy involving f ruit f lies show ed t hat by manipulat ing an individual gene, male f ruit f lies could be made t o init iat e homosexual court ship.15 It is int erest ing t o not e t hat t he male f ruit f lies t hat had not been genet ically modif ied nevert heless also engaged in court ship and sexual behaviour w it h t he ‘homosexual’ f ruit f lies. How ever, t he issue of t he ext ent t o w hich human t rait s can be meaningf ully compared t o animal behaviour seems part icularly pert inent in t he cont ext of sexual orient at ion, in view of t he many f acet s of t his t rait in humans, beyond overt , observable behaviours:

O F

Current findings: research involving animals

REV I EW

10.17 In 1999, Hamer combined t he dat a f rom t hese f our st udies and est imat ed t he percent age of brot hers w ho shared t he Xq28 region at 64% . While t his result is less signif icant t han his init ial result , Hamer’s met a-analysis of DNA linkage dat a cont inues t o support t he hypot hesis t hat Xq28 may cont ain genes t hat have a role in sexual orient at ion in males, but indicat es t hat t he associat ion is not as st rong as w as f irst suggest ed.

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10.16 In 1998, Sanders et al replicat ed t he w ork in a st udy involving 54 homosexual sibling pairs. They f ound t hat 66% of t he pairs of brot hers shared t he Xq28 region. Their w ork w as present ed at t he American Psychiat ric Associat ion Annual M eet ing in Toront o in 1998 but has not yet been f ormally published. In a similar-sized sample t o t he Sanders et al st udy, Ebers and Rice f ound no indicat ion t hat Xq28 cont ained a gene t hat inf luenced sexual orient at ion.13 They examined 52 pairs of homosexual brot hers and f ound t hat only 46% shared t he Xq28 region, w hich w as not st at ist ically signif icant . Their st udy dif f ered f rom t he original w ork in t hat it did not select part icipant s on t he basis of evidence of mat ernal t ransmission. How ever, t he researchers argued t hat even if t his met hodology w ere applied, t heir dat a w ould st ill f ail t o yield signif icant result s.

CH A PTER

10.15 Tw o years af t er Hamer’s original st udy, his group of researchers replicat ed t he Xq28 f inding, but w it h less signif icant result s, and using a smaller number of f amilies.12 They f ound t hat 67% of homosexual brot hers had inherit ed t he same Xq28 region as each ot her. The researchers also f ound t hat t here w as no signif icant linkage f or homosexual f emale siblings.

‘f lies do not have belief s and desires. This is a quit e serious object ion t o t he view t hat f lies have sexual orient at ions in anyt hing like t he sense t hat humans do and, t hereby, t he view s t hat f lies can be usef ul models of human sexual desire’.16

12

Hu, S. et al. (1995). Linkage bet w een sexual orient at ion and chromosome Xq28 in males but not in f emales. Nat . Genet . 11, 248–56.

13

Rice, G., Anderson, C., Risch, N. & Ebers, G. (1999). M ale homosexualit y: absence of linkage t o microsat ellit e markers at Xq28. Science 23, 665–7.

14

See, f or example, Vines, G. (1999). Queer Creat ures [edit orial]. New Scient ist 7 August .

15

Zhang, S.-D. & Osw ald, W. F. (1995). M isexpression of t he w hit e (w ) gene t riggers male–male court ship in Drosophila. Proc. Nat l. Acad. Sci. USA 92, 5525–9.

16

St ein, E. (1999). The M ismeasure of Desire: t he Science, Theory and Et hics of Sexual Orient at ion. Oxf ord: Oxf ord Universit y Press. pp. 167–9.

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Current findings: other biological influences 10.19 The research int o genet ic inf luences on sexual orient at ion does not provide any inf ormat ion about t he mechanisms by w hich genes might inf luence behaviour. How ever, a number of st udies have examined physiological f eat ures t hat may be correlat ed w it h sexual orient at ion. In 1991, LeVay conduct ed research int o an area of t he brain called t he ant erior hypot halamus, w hich cont ains f our cell groups called t he int erst it ial nuclei of t he ant erior hypot halamus (INAH).17 The INAH neurons had already been show n t o be larger in men t han in w omen, and LeVay hypot hesised t hat t hey could be relevant in sexual behaviour. His research f ound t hat a part icular group of neurons called INAH3 w as signif icant ly larger in het erosexual men t han in homosexual men. How ever, his research w as crit icised f or using as it s sample t he brains of men w ho had died of AIDS, since it w as possible t hat t he disease may have af f ect ed t heir brains, and f or having a small sample of only 41 people. Le Vay not ed t hat his research lef t open t he quest ion of w het her ‘t he st ruct ural dif f erences w ere present at birt h and lat er inf luenced t he men t o become gay or st raight , or w het her t hey arose in adult lif e, perhaps as a result of t he men’s sexual behaviour’.18 10.20 The same year, ot her researchers show ed t hat a bundle of nerves t hat connect s a small region of t he right and lef t sides of t he brain, t he ant erior commissure, is bigger in homosexual men t han in het erosexual men.19 How ever, evidence of a correlat ion bet w een aspect s of brain st ruct ure and a behavioural t rait does not by it self provide any guidance on w hich came f irst , or w het her bot h are inf luenced by an ent irely separat e variable. The idea of neuroplast icit y – t hat experience it self changes t he w ay t he brain is f ormed – is an import ant concept . 10.21 Ot her researchers have examined t he possibilit y t hat exposure t o part icular hormones and chemicals bef ore birt h may be linked t o sexual orient at ion lat er in lif e. In 1994, it w as report ed t hat homosexual men have a lef t w ard asymmet ry in t he number of ridges on t heir f ingerprint s.20 Fingerprint ridge development t akes place bef ore birt h and is inf luenced by androgens released f rom t he mot her t o t he f et us. Androgens are also t hought t o be responsible f or f inger lengt h, and a recent st udy show ed t hat t he rat io of second f inger lengt h t o f ourt h f inger lengt h is great er in w omen t han in men; w omen’s f ingers are on average more similar in lengt h.21 Homosexual w omen had a signif icant ly smaller rat io t han het erosexual w omen (in ot her w ords, t heir hands w ere more like men’s hands) but no signif icant diff erence w as f ound bet w een homosexual men and het erosexual men. How ever, as t he researchers not ed, t here is considerable overlap and it is not possible t o use f inger rat ios t o predict sexual orient at ion w it h any accuracy. 10.22 In 1998, Ellis report ed t hat very high levels of st ress during t he second t rimest er of

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17

Le Vay, S. (1991). A diff erence in hypot halamic st ruct ure bet w een het erosexual and homosexual men. Science 253, 1034–7.

18

Le Vay, S. (1993). The Sexual Brain. Cambridge, M A: M IT. p.122.

19

Allen, L. S. & Gorski, R. A. (1992) Sexual orient at ion and t he size of t he ant erior commissure in t he human brain. Proc. Nat l. Acad. Sci. USA 89, 7199–202.

20

Hall, J. A. Y. & Kimura, D. Dermat oglyphic asymmet ry and sexual orient at ion in men. Behav. Neurosci. 108, 1203–6.

21

Williams, T. J. et al. (2000). Finger-lengt h rat ios and sexual orient at ion. Nat ure 404, 455–6.

22

Ellis, L., Ames, M . A., Peckham, W. & Burke, D. (1988). Sexual orient at ion of human off spring may be alt ered by severe mat ernal st ress during pregnancy. J. Sex Res. 25, 152–7. See also Ridley, M (1993). The Red Queen. London: Penguin. pp. 264–5.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

EV I D EN CE: SEX U A L O RI EN TATI O N

23

TH E

10.25 Thirdly, it is not clear w het her researchers in behavioural genet ics are able t o def ine and measure sexual orient at ion adequat ely or comprehensively. One st udy has demonst rat ed t hat report ed rat es of f amilial homosexualit y diff er depending on t he crit eria used t o def ine t he t rait .29 As discussed, diff erent scales are used in diff erent project s. Some rely on simple quest ions, such as ‘Have you ever had a f ant asy about a member of t he same sex?’, w hich might be expect ed t o generat e higher rat es of homosexual orient at ion t han t hose scales w hich ask about lif e experiences and self -ident if icat ion. The st udy by Kendler et al simply asked ‘How w ould you describe your sexual orient at ion? Would you say you are het erosexual, homosexual or bisexual?’ As t he researchers not e, ‘t he assessment of t he complex phenot ype of sexual orient at ion w it h a single it em is f ar f rom ideal’.30 How ever, it

O F

10.24 Secondly, t he met hod of recruit ment of part icipant s has been crit icised, not least by t he researchers t hemselves. There are numerous problems associat ed w it h self -select ing samples, in part icular, ascert ainment bias. In t he case of t w ins, f or example, ‘t he most likely w ay in w hich t his w ould occur is t hat gay men w hose t w ins are also gay w ould be more w illing t o volunt eer t han gay men w it h het erosexual t w ins’ 28 perhaps because of t he f ear of conf lict bet w een t w ins w it h diff erent orient at ions.

REV I EW

10.23 There are numerous problems w it h genet ic and ot her biological research int o sexual orient at ion w hich mean t hat any report ed f indings must be view ed w it h caut ion. First , st udies in molecular genet ics have relied on very small sample sizes, usually f ew er t han 100 homosexual part icipant s. Recruit ing enough part icipant s t o obt ain suff icient st at ist ical pow er appears t o be diff icult , and t he problem of small samples may account f or t he f ailure t o replicat e t he Xq28 f inding conclusively. Tw in st udies f ace similar problems of sample size, of w hich t he researchers are aw are. In report ing research t hat t est ed 71 ident ical t w in pairs and 37 non-ident ical t w in pairs, Bailey et al st at e ‘w e urge t hat our result s be evaluat ed caut iously … t hey are not conclusive’.27

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Critical assessment of the validity of this evidence

CH A PTER

pregnancy increases t he probabilit y t hat a male child is homosexual.22 Ot her f indings include an increased rate of left-handedness among homosexuals,23 worse performance on visuospatial tasks by homosexual men compared to heterosexual men,24 and an association, at least in women, between sexual orientation and exposure prenatally to particular hormones.25 The f indings in t his area of research int o sexual orient at ion has led some comment at ors t o conclude t hat hormones have a key role in sexual orient at ion: ‘The “ gay gene” … is w idely expect ed t o t urn out t o be a series of genes t hat aff ect t he sensit ivit y of cert ain t issues t o t est ost erone.’ 26

See, f or example, Got est am, K. O. et al. (1992). Handedness, dyslexia and t w inning in homosexual men. Int . J. Neurosci. 63, 179; M cCormick, C. Wit elson, S. & Kingst one, E. (1990). Lef t -handedness in homosexual men and w omen: neuroendocrine implicat ions. Psychoneuroendocrinology. 15, 69–76.

24

Gladue. B. A. & Beat t y, W. W. (1990). Sexual orient at ion and spat ial abilit y in men and w omen. Psychobiology 18, 101–8.

25

M cCormick, C. Wit elson, S. & Kingst one, E. (1990). Lef t -handedness in homosexual men and w omen: neuroendocrine implicat ions. Psychoneuroendocrinology. 15, 69–76.

26

Ridley, M (1993). The Red Queen. London: Penguin.

27

Bailey, J. M ., Pillard, R. C., Neale, M . C. & Agyei, Y. (1993). Herit able f act ors inf luence f emale sexual orient at ion. Arch. Gen. Psychiat . 50, 217–23.

28

Bailey, J. M . & Pillard, R.C. (1995). Genet ics of human sexual orient at ion. An. Rev. Sex Res. 6, 126–50.

29

Bailey, J. M . & Benishay, D. (1993). Familial aggregat ion of f emale sexual orient at ion. Am. J. Psychiat . 150, 272–7.

30

Kendler, K. S., Thornt on, L. M ., Gilman, S. E. & Kessler, R. C. (2000). Sexual orient at ion in a US nat ional sample of t w in and nont w in sibling pairs. Am. J. Psychiat . 157, 1843–6.

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is not clear w het her using mult iple scales could circumvent t his problem, nor is it clear w het her at t empt s t o int egrat e t he diff erent aspect s of sexual orient at ion could ever accurat ely ref lect t he component s of human sexual pref erences. The implicat ions of disagreement about w hat count s as homosexualit y f or research are import ant , as t he cat egory in w hich individuals are placed and t he rat e of sexual orient at ion est imat ed in t he general populat ion w ill bot h aff ect w het her result s appear signif icant . There is a t endency deliberat ely t o conf lat e homosexualit y and bisexualit y in order t o achieve more st at ist ical pow er. Furt hermore, researchers t hemselves are int ernally inconsist ent w it h t heir classif icat ion. In t he st udy by Bailey and Pillard described above, t he researchers st udy bot h homosexual and bisexual males and calculat e concordance rat es accordingly, but t heir conclusions ref er only t o homosexualit y. 10.26 A f undament al concept ual diff icult y must be addressed by researchers in t his f ield: is sexual orient at ion a dimorphic, t rimorphic, or cont inuously dist ribut ed t rait ? That is t o say, are t here t w o or t hree dist inct cat egories of sexual orient at ion or is t here a spect rum of orient at ion? M any st udies place homosexual and bisexual people in one cat egory and cont rast t hem w it h het erosexual people. This could suggest eit her t hat sexual orient at ion is view ed as a cont inuously dist ribut ed t rait w it h easily def ined point s along it , or t hat t he various orient at ions are ent irely dist inct . The f ormer posit ion is aff lict ed by t he crit icisms out lined regarding t he measurement of t he t rait (paragraph 10.25). The lat t er posit ion w as t aken by Hamer in his research int o Xq28. He f ound t hat t here w as lit t le overlap bet w een individuals’ self -report s on t he Kinsey scale on f our diff erent aspect s of sexualit y: self ident if icat ion, at t ract ion, f ant asy and behaviour. Around 90% of individuals classed t hemselves as eit her 0 or 1, or 5 or 6 in all areas. Theref ore, ‘it w as appropriat e t o t reat sexual orient at ion as a dimorphic rat her t han as a cont inuously variable t rait ’. It is int erest ing t o not e t hat despit e t he use of measures such as t he Kinsey scale, w hich w as developed in order t o ref lect t he spect rum of human sexual behaviour, some researchers nevert heless regard sexual orient at ion as dimorphic, and cat egorise t he result s of Kinsey quest ionnaires accordingly. A f urt her problem is t hat t here is no consensus about w het her homosexualit y in men and w omen is t he same t ype of t rait , or has t he same origins in bot h sexes. It has been suggest ed t hat t he specif ic genet ic inf luences on sexual orient at ion w ill be dif f erent f or males t han f or f emales.31 All t hese uncert aint ies cont ribut e t o inconsist encies across research project s w hich make replicat ion and comparison diff icult , and allow great variat ion in t he int erpret at ion of result s.

Evolutionary arguments against genetic influences on homosexuality 10.27 An argument of t en made against t he possibilit y t hat homosexualit y has a genet ic origin is t hat such genes w ould not ‘survive’ in evolut ionary t erms, because gay couples generally do not have children. Various possible explanat ions f or t he survival of genes t hat inf luence homosexualit y have been put f orw ard. One is t hat t he gene or genes in quest ion have a benef icial eff ect on f emale f ert ilit y, meaning t hat w omen w it h t he relevant genes are likely t o have more children. Anot her possibilit y is t hat t he genes are part of f emale mit ochondrial DNA. If t hat w ere t he case, t hey w ould be inherit ed by bot h male and f emale off spring, but only t he f emale off spring w ould go on t o reproduce. The result ing reduct ion of compet it ion f or resources among t he ext ended f amily might have enhanced t he reproduct ive success of t he f emales.32 Anot her suggest ion is t hat homosexual f amily

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31

Bailey, J. M ., Pillard, R. C., Neale, M . C. & Agyei, Y. (1993). Herit able f act ors inf luence f emale sexual orient at ion. Arch. Gen. Psychiat . 50, 217–23.

32

Ridley, M (1993). The Red Queen. London: Penguin.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

REV I EW O F TH E EV I D EN CE:

10.28 Research int o genet ic inf luences on sexual orient at ion cont inues. Hamer and his colleagues are at t empt ing t o locat e specif ic genes w it hin t he Xq28 region, alt hough he has st at ed t hat ‘There is no “ gay gene” and I have never t hought t here w as. Genes play a role, and t here are probably more t han one of t hem, and ot her f act ors as w ell.’ 33 Ot her researchers are at t empt ing t o replicat e Hamer’s Xq28 research w it h larger samples, and t o ident if y ot her regions of DNA t hat might be involved. Ongoing project s include t he Aust ralian Tw in St udy of Sexual At t it udes and Behaviour,34 w it h dat a on almost 5,000 t w ins, and t he Gay Brot hers St udy,35 w hich has bot h molecular genet ic and psychological component s.

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Future directions for research

CH A PTER

members cont ribut e t o t he reproduct ive success of an ext ended f amily by assist ing w it h raising off spring. Finally, it has been proposed t hat homosexualit y may be associat ed w it h anot her t rait w hich is linked w it h improved reproduct ive success. All t hese hypot heses are no more t han speculat ion: it is exceedingly diff icult t o guess how evolut ion may have w orked w it h regard t o a part icular genet ic variant . Such argument s are of very lit t le value in answ ering t he quest ion of w het her a genet ic inf luence on a t rait exist s.

SEX U A L O RI EN TATI O N

33

Lehrman, S. (1995). ‘Gay gene’ st udy under scrut iny. San Francisco Examiner 7 July.

34

Research on t his project is led by Prof essor N M art in, Queensland Inst it ut e of M edical Research, Aust ralia.

35

Research on t his project is led by Dr Khyt am Daw ood, Nort hw est ern Universit y and Prof essor Richard Pillard, Associat e Prof essor of Psychiat ry, Bost on Universit y.

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Chapter Cent ral t hemes f rom t he review s of t he evidence

11

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REV I EW S O F TH E EV I D EN CE

Estimates of heritability

TH E

11.3 The t rait s on w hich research in behavioural genet ics f ocuses are complex and mult i-f acet ed. The diff icult y of def ining such t rait s in a rigorous and reproducible manner is a problem t hat equally aff ect s psychologist s and ot her researchers of human behaviour. Scores on scales of aggression, neurot icism or capacit y f or memory are usef ul t ools f or researchers and have applicat ions in t he realm of clinical psychology. How ever, broader claims f rom research in behavioural genet ics about inf luences on human behaviour must be accompanied by a caveat about t he necessarily art if icial and limit ed cont ext in w hich t rait s are considered.

FRO M

The difficulty of defining and measuring traits

TH EM ES

11.2 As t he review s of t he evidence demonst rat e, research is at dif f erent st ages in dif f erent areas. For some t rait s, areas of t he genome have been ident if ied t hat might cont ain genes w hich have an ef f ect on behaviour. For most t rait s, t he rout e f rom such genet ic f act ors t o a part icular behaviour is unclear. To dat e, most research in behavioural genet ics has relied on quant it at ive met hods (see Chapt er 4) t o assess t he relat ive cont ribut ions of dif f erent t ypes of f act or. How ever, t he use of molecular genet ics (see Chapt er 5) is increasing, a t rend w hich is expect ed t o cont inue. In t his chapt er, w e draw some general conclusions about t he research in t he f our select ed areas and highlight some cent ral t hemes t hat emerge. These w ill inf orm our considerat ion, in t he next sect ion of t his Report , of t he et hical, legal, social and policy issues t o w hich t he research gives rise.

CEN TRA L

11.1 The f our preceding chapt ers have set out some recent f indings f rom research in behavioural genet ics int o int elligence, personalit y, ant isocial behaviour and sexual orient at ion. These areas of research w ere select ed t o illust rat e t he breadt h of t opics w hich researchers in behavioural genet ics are invest igat ing and t o include t hose areas in w hich pract ical applicat ions of t he research might be likely.

1 1

Introduction

CH A PTER

Cent ral t hemes f rom t he review s of t he evidence

11.4 As not ed in Chapt er 4, t he est imat es of herit abilit y derived f rom quant it at ive research met hods apply only t o part icular groups of people, and represent t he percent age of t he variat ion in a t rait t hat can be account ed f or by genet ic inf luences, among t he members of t hat group, at t he t ime of st udy. Thus, an est imat e of t he herit abilit y of a t rait does not provide any inf ormat ion about t he number or ident it y of t he genes t hat may be involved. M ost calculat ions of herit abilit y assume t hat t he genet ic inf luences in quest ion w ork t oget her in an addit ive f ashion, so t hat if t w o hypot het ical genet ic f act ors cont ribut ed 5% of t he variance each, t oget her t hey w ould cont ribut e 10% of t he variance. How ever, it is likely t hat in many cases, t he act ion of genes w ill depend on t he presence of ot her genes and on part icular environment al f act ors. Such eff ect s can be overlooked by quant it at ive t echniques. Furt hermore, because herit abilit y is a rat io of variat ion t hat has a genet ic origin t o t he t ot al variat ion, changes in t he degree of variat ion t hat has an environment al origin w ill aff ect t he est imat e of herit abilit y, even if t he genet ic cont ribut ion t o t he t rait in quest ion does not change.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

11.5 Est imat es of herit abilit y ref er only t o t he populat ion sample on w hich t hey w ere calculat ed. If similar est imat es are obt ained across many st udies t hat have diff erent f eat ures, such as nat ionalit y, hist orical period and so on, t his w ill show t hat t he est imat e can be generalised t o some ext ent . It is commonly acknow ledged by researchers in behavioural genet ics t hat est imat es of herit abilit y f or most human t rait s t hat have been measured are in t he region of 0.40 t o 0.60. Wit hin t his general range, some t rait s, f or example int elligence (Chapt er 7), appear t o be more herit able t han ot hers, f or example ant isocial behaviour (Chapt er 9). For t he reasons given above, t his inf ormat ion alone is of comparat ively lit t le value, except in so f ar as it only show s t hat t here is some genet ic inf luence, of w hat ever sort , on a part icular t rait , and t hus makes t he t rait a pot ent ially w ort hw hile candidat e f or molecular research. Such est imat es are cert ainly not an appropriat e basis f or making claims about part icular individuals, or f or social policy.

The lack of replicated findings in molecular genetics 11.6 As w e have seen, t he t ask of f inding genes t hat inf luence complex human behaviours is a diff icult one. The review s of t he evidence have show n t hat t here are very f ew conf irmed and replicat ed f indings in molecular genet ics. No individual gene has been ident if ied in humans t hat inf luences sexual orient at ion, ant isocial behaviour or int elligence w it hin t he normal range. One gene variant , called monoamine oxidase A (M AOA), has been associat ed w it h low int elligence and aggression but so f ar, only in one f amily (paragraph 9.24). One st udy has indicat ed an eff ect of t his genot ype w hen combined w it h delet erious environment al condit ions in male children, but t his st udy aw ait s replicat ion (paragraph 9.25). Anot her gene variant , called t he dopamine recept or D4 gene (DRD4), has been associat ed w it h a handf ul of personalit y t rait s, psychiat ric condit ions and ot her behaviours, but t he evidence remains inconclusive f or it s associat ion w it h t rait s in t he normal range (paragraphs 5.10 and 8.12). A gene t hat aff ect s a chemical in t he brain called serot onin has been associat ed w it h anxiet y (paragraph 8.12). An alcohol-met abolising enzyme t hat prot ect s against alcoholism has also been ident if ied (Chapt er 5, f oot not e 1), alt hough t his lat t er f inding can be view ed as relat ing t o a t rait out side t he normal range. Of course, w hen w e consider t hat genet ic inf luences on complex diseases such as diabet es and ast hma are proving diff icult t o dissect , it is perhaps unsurprising t hat research on probably more complex behavioural t rait s should be even less advanced.

Applications of current research findings 11.7 In light of t he lack of f indings t hat have been replicat ed in research in behavioural genet ics using molecular genet ics t echniques in t his f ield, t here are current ly no pract ical applicat ions of t he research. There are no genet ic t est s f or behavioural t rait s, nor are t here pharmacological int ervent ions t hat have been developed based on inf ormat ion about genet ic inf luences on behavioural t rait s in t he normal range. 11.8 Wit h regard t o int elligence, t he only case w here it seems plausible t o see int ervent ions based on genet ic know ledge in t he near f ut ure is t hat of serious ment al ret ardat ion (see paragraph 7.14). How ever, f ut ure applicat ions w it h regard t o int elligence in t he normal range cannot be ruled out , subject t o t he qualif icat ions set out in t his Report about t he predict ive accuracy of genet ic t est s f or behavioural t rait s. 11.9 Scores on measures of personalit y can be moderat ely usef ul in predict ing t he likelihood of behavioural t rait s and disorders being exhibit ed in t he f ut ure. For example, t hose w ho have a high score on t he psychological scale of Neurot icism have an elevat ed chance of developing a neurot ic disorder. Similarly, t hose w it h a high score w ho are aff ect ed by a 1 1 2

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

FRO M TH E REV I EW S O F TH E EV I D EN CE

11.12 Research w hich claims t o show an associat ion bet w een part icular genet ic variant s and part icular t rait s t ends t o receive considerable at t ent ion in t he scient if ic and lay media. Research in genet ics and research t hat aims t o show w hy human beings behave as t hey do (f or example psychological and sociological research) are bot h subject s of enormous int erest t o societ y, so it is perhaps unsurprising t hat , w hen combined in t he f orm of research in behavioural genet ics, any f indings are w idely report ed and discussed.

TH EM ES

Reporting research in behavioural genetics

CEN TRA L

11.11 To dat e, no gene t hat aff ect s sexual orient at ion in humans has been ident if ied (see paragraphs 10.14–10.17). Thus, t here are current ly no pract ical applicat ions of t he research, in t erms of t he use of genet ic t est s f or predict ive purposes.

1 1

11.10 In t he cont ext of ant isocial behaviour, t here are current ly no pract ical applicat ions of t he research. One st udy suggest s t hat a part icular gene, M AOA, might have an eff ect on ant isocial behaviour in males, depending on w het her individuals are malt reat ed as children. If replicat ed, t his f inding could have implicat ions f or prevent ing ant isocial behaviour (see paragraph 9.25).1 The f inding f rom ot her research in t he f ield, t hat genet ic variance inf luences behaviour, but is not necessarily associat ed w it h off icial eff ort s t o cont rol behaviour, may help add clarit y t o t he cont roversy about w het her or not off ending is herit able. The st at us of juvenile delinquent and t he convict ion of adult s in law court s are socio-polit ical-legal const ruct ions, and on t he basis of t his t ruism, scholars have quest ioned how such const ruct ions could possibly be inherit ed. Research suggest s t hat a dist inct ion bet w een ant isocial t rait s w hich are herit able and delinquent /convict ion st at us, part icularly among juveniles, w hich is less herit able, is a crucial one. Inf ormat ion f rom research in behavioural genet ics is unlikely t o be relevant t o individual cases in juvenile court proceedings. (See Chapt ers 14 and 15 f or considerat ion of t he use of inf ormat ion about genet ic inf luences on behaviour w it h regard t o legal pract ice and social policy.)

CH A PTER

disast er have a higher probabilit y of developing post -t raumat ic st ress disorder. These predict ions are already made w it h t he measures of personalit y used by psychologist s. It is not clear w het her, in t he adult populat ion, addit ional inf ormat ion about genet ic f act ors w ill add t o t hese abilit ies t o make predict ions. How ever, t he abilit y t o make predict ions based on genet ic inf ormat ion might , in principle, be used t o devise int ervent ions such as environment al manipulat ions t hat modif y t he genet ic cont ribut ion. So, f or example one might choose t o provide an environment t hat w ould develop courage in a child w it h a genet ic suscept ibilit y t o t imidit y.

11.13 How ever, w e not ed in Chapt ers 4–6 t hat t he various met hods of research in t his f ield are not inf allible, and t he review s of t he evidence in Chapt ers 7–10 have show n t hat f ew f indings have been replicat ed successf ully t o dat e. Thus, report s of such t hings as ‘gay genes’ or ‘smart mice’ convey a highly inaccurat e impression of t he st at e of t he research. The lack of report ing of negat ive or cont radict ory f indings exacerbat es t his problem. These diff icult ies are not unique t o research in behavioural genet ics. How ever, it does seem t hat such research is, at present , part icularly suscept ible t o report ing w hich, w het her st rict ly accurat e or not , is misleading in t he impression it gives t o t he reader. The pot ent ial f or t he abuse of f indings in t his area means t hat t he report ing of t his research ought t o be conduct ed w it h part icular care.

1

Brunner, H. G., Nelen, M ., Breakef ield, X. O., Ropers, H. H & van Oost , B. A. (1993). Abnormal behaviour associat ed w it h a point mut at ion in t he st ruct ural gene f or monoamine oxidase A. Science 262, 578–80.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

11.14 We consider t hat researchers and t hose w ho report research have a dut y t o com m unicat e f indings in a responsible m anner. We w elcom e t he Guidelines on Science and Healt h Com m unicat ion published by t he Social Issues Research Cent re, t he Royal Societ y and t he Royal Inst it ut ion of Great Brit ain and recom m end t hat f urt her init iat ives in t his area should be encouraged.2

Funding research in behavioural genetics 11.15 It has proved diff icult t o gauge t he precise ext ent of UK f unding in t his area. In response t o our public consult at ion, t he M edical Research Council (M RC) st at ed t hat ‘f unding f or UK research in behavioural genet ics is modest ’. One problem w it h obt aining a more precise account is t hat , as w e have repeat edly observed in t his Report , t here is no clear line bet w een behaviour in t he normal range and t hat w hich const it ut es a disorder. M oreover, since it may be t hat t he same genes t hat aff ect behaviour at t he ext remes of variat ion, w hich may be seen as disorders, also aff ect behaviour w it hin t he normal range, it w ill be diff icult t o dist inguish research t hat f ocuses on t he normal range f rom t hat w hich f ocuses on t he ext remes. It is possible t hat research w hich at t empt s t o ident if y genes t hat aff ect ext remes of behaviour may have implicat ions f or behaviour in t he normal range, and conversely, t hat research t hat f ocuses on behaviour in t he normal range may have implicat ions f or t hat at t he ext remes. For example, research suggest s t hat t he genet ic f act ors w hich cont ribut e t o depression, w hich is a disorder, also cont ribut e t o t he t rait of negat ive emot ionalit y, w hich is a t rait t hat is cont inuously dist ribut ed t hroughout t he populat ion. This phenomenon also arises in research int o diseases; f or example, research int o normal blood pressure may be usef ul in underst anding hypert ension. 11.16 Not w it hst anding t he diff icult y in delineat ing research in behavioural genet ics t hat f ocuses on behaviour in t he normal range, t he M RC st at ed in it s response t hat it ‘does not give grant s f or research int o t he genet ics of w hat are seen as “ normal” variat ions in behaviour or personalit y, but [does] f und w ork relevant t o aspect s of behaviour seen by societ y as signif icant medical, psychological or educat ional problems’. The M RC not es t hat research int o genet ic inf luences on t rait s in t he normal range such as ‘general int elligence’ could have value, but t hat t he M RC ‘does not give grant s f or such w ork because w e have a medical remit , and t o us, t he benef it s do not clearly out w eigh t he risks’. In 1997, t he M RC developed a policy on research in behavioural genet ics and devised a list of crit eria against w hich pot ent ial research project s should be assessed. This includes t he possible misuse of t he research f indings. In it s response t o t he consult at ion, t he Wellcome Trust st at ed t hat ‘some of t he research w e f und looks at “ normal” (or milder) t rait s and ot her project s f ocus on “ abnormal” variat ions’. 11.17 Our public consult at ion show ed t hat many people consider t hat , compared t o research on disease, research int o genet ic inf luences on behavioural t rait s in t he normal range ought t o receive low priorit y f or f unding. This w as part ly due t o doubt s about t he likely success of t he research, and part ly due t o concerns about t he pot ent ial applicat ions. We t ake t he view t hat research in behavioural genet ics has t he pot ent ial t o advance our underst anding of hum an behaviour and t hat t he research can t heref ore be just if ied. How ever, w e not e t hat it is im port ant t hat t hose w ho f und research in t his area should cont inue t o f und research of a high calibre,

2

1 1 4

Social Issues Research Cent re, t he Royal Societ y and t he Royal Inst it ut ion. Guidelines on Science and Healt h Communicat ion. November 2001. ht t p://w w w.sirc.org/publik/revised_guidelines.pdf (9 Aug 2002).

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

CH A PTER

should be t ransparent about t heir f unding pract ices and should be aw are of t he pot ent ial f or t he abuse and m isint erpret at ion of result s. In addit ion, w e recom m end t hat research sponsors w ho int end t o f ocus st rat egic f unding in t his area should pay caref ul at t ent ion t o public concerns about t he research and it s applicat ions.

1 1 TH EM ES

11.18 This sect ion of t he Report has summarised t he current evidence f or genet ic inf luences on a select ion of behavioural t rait s. It is clear t hat very lit t le is yet know n about part icular genet ic f act ors and t heir roles in inf luencing behaviour. How ever, a considerable amount of research is under w ay t hat aims t o improve our underst anding in t his f ield. We not e t he need f or caref ul and accurat e report ing of research f indings. In t he f ollow ing sect ion of t he Report , w e move on t o consider t he possible implicat ions f or societ y if such programmes of research are successf ul.

CEN TRA L

Conclusion

FRO M TH E REV I EW S O F TH E EV I D EN CE 1 1 5

Section Et hical, legal, social and policy issues

4

Chapter Genet ics, f reedom and human dignit y

12

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

FREED O M A N D H U M A N D I GN I TY

12.3 This pot ent ial of research in behavioural genet ics t o undermine t he w ay in w hich w e t hink of ourselves can be cont rast ed w it h t he implicat ions of discoveries in genet ic research as it relat es t o disease and disorder. In t he lat t er case, research has est ablished t hat , f or example, some people may have a genet ic predisposit ion t o breast cancer. Finding out t hat one is aff ect ed in t his w ay, how ever dist ressing, need not undermine one’s sense of one’s ow n ident it y. By cont rast , w hat is suggest ed by research in behavioural genet ics is t hat aspect s of an individual’s charact er, one’s personal ident it y, may have a genet ic basis. Thus, w hereas in t he case of disease and disorder, it is easy t o diff erent iat e oneself f rom t hat t o w hich one is genet ically predisposed, in t he case of behaviour, it appears t hat one cannot do likew ise; t here is no deeper self w hich is unaff ect ed by one’s genes.

GEN ETI CS,

12.2 This sense of responsibilit y is not just a mat t er of legal concern. (This aspect of responsibilit y is discussed in Chapt er 14.) Perhaps more import ant ly, it is an essent ial ingredient in t he concept ion of human dignit y, in t he presumpt ion t hat one is a person w hose act ions, t hought s and concerns are w ort hy of int rinsic respect , because t hey have been chosen, organised and guided in a w ay w hich makes sense f rom a dist inct ively individual point of view. If it t urns out t o be an illusion t o suppose t hat people are responsible f or t hemselves, t hen t heir act ions and t hought s do not belong t oget her as part of t he meaningf ul lif e of an individual; a moral subject . In w hich case, one of t he most f undament al reasons w hich people have f or t reat ing each ot her as w ort hy of respect w ould have been undermined.

1 2

12.1 Alt hough t he review s of t he evidence in Chapt ers 7–10 indicat e t hat very lit t le is yet know n about part icular genet ic f act ors t hat inf luence behaviour in t he normal range, t here can be no doubt t hat genes do make some cont ribut ion t o behavioural t rait s, including f undament al aspect s of human charact er. Since people do not choose t heir genes, and are t heref ore not responsible f or t hem, it seems t o f ollow t hat t hey are not responsible f or t hese aspect s of t heir charact er. But if t his is so, t hen how f ar are t hey responsible f or t hemselves at all? Does research in behavioural genet ics undermine t he normal sense of responsibilit y?

CH A PTER

Genet ics, f reedom and human dignit y

12.4 It is import ant , nonet heless, t o underst and f rom t he st art t hat such anxiet ies should not be occasioned simply by t he recognit ion t hat people st art out t heir lives w it h diff erent abilit ies and w eaknesses. If ‘Tuesday’s child is f ull of grace’ w hereas ‘Wednesday’s child is f ull of w oe’, w oef ul Wednesday is likely t o have a harder st art t o lif e t han gracef ul Tuesday; but t his does not of it self imply t hat t he children w ill not develop int o adult s w ho are capable of t aking responsibilit y f or t heir ow n charact er. Unless she is very unlucky, w oef ul Wednesday should be able t o cont rol her depression, and gracef ul Tuesday w ill need t o t ake care of his charms. 12.5 Thus, if it can be show n t hat behavioural genet ics, properly underst ood, does not t hreat en t he concept ion of a person as a rat ional being capable of t aking responsibilit y f or himself or herself in f ree act ion, t hen it ought t o be possible t o w elcome t he deeper underst anding of t he springs of human mot ivat ion w hich behavioural genet ics promises, w it hout f eeling t hat t here is t hereby a t hreat t o t he inherent dignit y of humanit y. Theref ore, in t his chapt er, w e consider w het her behavioural genet ics does undermine our concept ions of personal ident it y and responsibilit y.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

The material self 12.6 Bef ore one can ident if y and discuss t his issue properly it is necessary t o set aside one t radit ional w ay of t hinking about ourselves. One view regarding t he implicat ions of behavioural genet ics is t hat t he research undermines t he not ion of responsibilit y simply because it reveals t he f act t hat many import ant mot ivat ions have a physical basis in genes. The assumpt ion here is t hat responsibilit y and t hus f ree w ill depend upon t he abilit y t o t ranscend all such physical condit ions. This t radit ional concept ion of f ree w ill st ems f rom t he concept ion of a person as comprising a mat erial (physical) body t hat is associat ed w it h an immat erial self w hich is revealed in consciousness and is, f or each person, w hat t hey ‘really’ are. The suggest ion is t hat even if one’s physical body is a part of t he nat ural w orld, t he act ions of t he immat erial self are no part of t his syst em. Inst ead t hey const it ut e a domain of f reedom in w hich a person cont rols t he course of t heir lif e. 12.7 This concept ion of f ree w ill is t hreat ened by behavioural genet ics in so f ar as it implies t hat (mat erial) genes aff ect t he mot ivat ions of t he (immat erial) self . But in any case, t his concept ion of f ree w ill is implausible. If t he immat erial self ’s exercise of it s f reedom is t o make any diff erence t o t he course of lif e, in ot her w ords, if ment al st at es are t o be causally eff ect ive, t he immat erial self ’s act s have t o make a diff erence t o t he bodily movement s w hich occur w henever one does anyt hing. But t he hypot hesis t hat t he act ions of an immat erial self can produce eff ect s upon a mat erial body is int rinsically myst erious: t here is no coherent w ay of underst anding how t his is possible. Inst ead, it seems inescapable t hat t he causes of change in t he mat erial w orld must t hemselves be, in some respect , mat erial. Hence t he only t enable underst anding of human f reedom is one w hich does not post ulat e an immat erial self as t he only really f ree agent . 12.8 It is w ort h observing t hat t his hypot hesis of a f ree immat erial self is not an essent ial ingredient of religious concept ions of human lif e. On t he cont rary, t he doct rine of incarnat ion is a cent ral f eat ure of t he Christ ian f ait h, including t he t hesis t hat t he ‘Word’ (human t hought s, f eelings, mot ivat ions and so on) really became ‘f lesh’, t hat is, mat erial. For t his reason, ort hodox Christ ianit y has also alw ays maint ained t hat lif e af t er deat h requires t he resurrect ion of a body.1 Thus, t here is no essent ial conf lict at t his point bet w een a mat erial view of t he w orld and Christ ianit y.2 12.9 It is diff icult t o charact erise brief ly t he at t it ude of ot her religions concerning t his issue of t he immat erial self . Belief in t he resurrect ion of t he dead arose in lat e second-t emple Judaism (see Daniel 12:2), but t here have been many w ays in w hich resurrect ion has been underst ood in Judaism, as in Christ ianit y. One especially inf luent ial view w as t hat of t he medieval Jew ish philosopher M aimonides.3 In his Guide t o t he Perplexed, M aimonides t reat ed mat erial exist ence as a necessary st age in t he soul’s liberat ion f rom sin t hrough suff ering, so t hat immort alit y is achieved w hen t he soul becomes purely rat ional and t hereby immat erial. This t ransf ormat ional concept ion of human exist ence, f rom a mat erial sinf ul lif e t o an immat erial pure af t erlif e, is also t o be f ound in Islam. It f it s readily w it hin a neo-Plat onist concept ion of t he self as essent ially immat erial but ‘imprisoned’ in a

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1

Cullman, O. (1958). Immort alit y of t he Soul or Resurrect ion of t he Dead? London: Epw ort h; Polkinghorne, J. (1994). The Fait h of a Physicist : Ref lect ions of a Bot t om-up Thinker. Princet on, NJ: Princet on Universit y Press.

2

The Christ ian t radit ion has also included t hinkers w it h neo-Plat onist view s more sympat het ic t o an immat erialist posit ion, but t heir posit ions have generally been regarded as het erodox (if not dow nright heret ical).

3

Kellner, M . (1990). M aimonides on Human Perf ect ion. At lant a, GA: Scholars Press.

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FREED O M A N D H U M A N D I GN I TY

12.11 In t hinking about t his posit ion, it is usef ul t o st art f rom a t hesis of t en associat ed w it h det erminist ic concept ions of human lif e, namely, f at alism. Fat alism is t he t hesis t hat t hat w hich is det ermined is ‘f at ed’: in ot her w ords, t hat it w ill t ake place w hat ever one chooses or at t empt s t o do. Tradit ionally, f at alism w as associat ed w it h myt hs concerning t he pow er of gods over human lif e.6 These myt hs are no longer believed, but f at alist language is st ill used t o describe inescapable aspect s of lif e, as w hen one says t hat everyone is ‘f at ed’ t o die. In a similar w ay, f at alist language can be used t o express t he view t hat genet ic discoveries imply t hat signif icant aspect s of lif e are inescapably f ixed by t he ident it y of one’s genes: as James Wat son has put it , ‘our f at e is in our genes’.7

GEN ETI CS,

12.10 One common ground f or t he view t hat genet ics undermines responsibilit y f or oneself is t he claim t hat genet ics is a det erminist ic t heory. This claim can be int erpret ed in many w ays, but in t he present cont ext it can be t aken as t he hypot hesis t hat t he law s of genet ics show t hat an individual’s genot ype det ermines an import ant range of f act s concerning his or her lif e, including f act s about a range of f undament al human abilit ies and disposit ions.

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Determinism and fatalism

CH A PTER

mat erial body during eart hly lif e; but Islamic t hought w as also much inf luenced by Arist ot le’s t hesis t hat t he soul is t he ‘f orm’ of t he body, a t hesis w hich cannot be readily combined w it h a concept ion of immat erial exist ence af t er deat h. Dif f erent Islamic t hinkers resolve t his t ension in dif f erent w ays: Ibn Sina (Avicenna) reject ed t he Arist ot elian posit ion in f avour of a neo-Plat onist concept ion of t he soul. His posit ion w as t hen crit icised by al-Ghazali, w ho insist ed on t he import ance of physical resurrect ion, since only a physical being can be punished f or sin. Finally Ibn Rushd (Averroes) ret urned t o an Arist ot elian posit ion w hile allow ing t hat w e can gain a kind of immort alit y as w e lose our individualit y in universal know ledge.4 These debat es show t he dif f icult y inherent in t he concept ion of an immat erial personal exist ence, and similar t ensions arise in East ern religions in t he cont ext of doct rines of reincarnat ion, karma and nirvana. But alt hough t hese doct rines imply t he possibilit y of a f orm of immat erial exist ence, t heir t heoret ical cont ext is not t he same as t hat of West ern religions and met aphysics, so t he quest ion of w het her t hey also permit a mat erialist concept ion of t he self is a complex one w hich cannot be pursued here.5

12.12 A dist inct t hesis is t hat of det erminism, w hich, in t his cont ext , is t he view t hat w hat w e choose t o do is det ermined by f act ors out side our cont rol. Non-f at alist det erminist s allow t hat an individual’s choice makes a diff erence t o t he course of his or her lif e, but hold t hat his choice has it self been det ermined. This is diff erent f rom t he f at alist t hesis because it means t hat our choices do play a causal role, w hereas t he f at alist believes t hat f ut ure event s w ill t ake place regardless of w hat w e choose. Nonet heless, many det erminist s are also f at alist s. This combinat ion is part icularly relevant here since, f at alism is clearly incompat ible w it h t he concept ion of ourselves as responsible moral agent s.

4

Nasr, O. & Leaman, O., edit ors. (1996). Hist ory of Islamic Philosophy. London: Rout ledge.

5

See f or example Collins, S. (1982). Self less Persons. Cambridge: Cambridge Universit y Press; Flahert y, W. D., edit or. (1980). Karma and Rebirt h in Classical Indian Tradit ions. Berkeley, CA: Universit y of Calif ornia Press.

6

For example, according t o Greek myt h, Apollo decreed t hat Oepidus, t he son of Laius, w ould kill his f at her and marry his mot her. Even t hough Laius, w hen t old of t his decree, at t empt ed t o avert his f at e by arranging t o have Oedipus killed as an inf ant , t he myt h recount s t hat Oedipus’ lif e w as saved and t hat he w ent on, unknow ingly, t o f ulf il Apollo’s decree.

7

Jaroff , L. (1989). The Gene Hunt . Time M agazine M arch 20.

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12.13 If it w ere t rue t hat genes have inescapable implicat ions concerning t he lat er course of lif e, t his f at alist language w ould be appropriat e. But it is f ar f rom evident t hat t hese implicat ions really are inescapable. In t he case of some diseases, t his is, in f act , t he case. For example, t hose w it h t he mut ant allele responsible f or Hunt ingt on’s disease are indeed f at ed t o develop t his condit ion, alt hough t his is f ort unat ely a rare condit ion. In t he case of most diseases, how ever, genet ic mut at ions lead only t o a predisposit ion, or risk, of developing a condit ion. M oreover, t here are generally also courses of act ion (such as a change of diet or lif est yle) w hich t hose diagnosed as being at risk can pursue in order t o lessen t he chance of t heir act ually developing t he condit ion in quest ion. So t hese cases, w hich are overw helmingly t he most common, are not cases in w hich t alk of f at alism is appropriat e. Phenylket onuria (PKU) is a good case in point . This is caused by a recessive allele of t he PAH gene 8 on chromosome 12 and is associat ed w it h serious ment al ret ardat ion. It t urns out t hat t his associat ion depends on f ollow ing a normal diet . Once someone ident if ied (soon af t er birt h, t hrough a blood t est ) as carrying t he t w o recessive alleles adopt s a diet low in t he amino acid phenylalanine, t his associat ion is broken and t he person concerned can develop relat ively normally. 12.14 It is, t hen, plain t hat underst anding t he eff ect s of our genes in t he case of disease does not lead us t o f at alism. In t he case of behaviour, t he review s of t he evidence in Chapt ers 7–10 demonst rat e t hat in so f ar as t here are genet ic inf luences on behaviour, t hese do not f ollow t he very rare pat t ern exemplif ied by Hunt ingt on’s disease. Inst ead t hese genet ic inf luences involve predisposit ions t o aggression, anxiet y, low or high int elligence and so on. They do not imply t hat t he chances of t hese predisposit ions being realised are unalt erable. On t he cont rary, w hen t he out come is undesirable, t heir discovery provides an incent ive f or int ervening t o enable t hose w it h t he predisposit ions t o learn how t o cont rol and overcome t hem. Equally, w hen t he out come is desirable, t hose f ound t o have t he relevant predisposit ion may be mot ivat ed t o make t he most of t heir genet ically given qualit ies. 12.15 Thus, t he eff ect of one’s genes is not t o f ix t he f ut ure st ruct ure of lif e as a f at e f rom w hich one cannot escape. Equally, t he eff ect is not t o f ix t he st ruct ure of one’s charact er, t he kind of person one is. Genes cert ainly cont ribut e t o t he init ial make-up of one’s abilit ies and mot ivat ions. But it does not f ollow t hat one cannot do t hings w hich develop t hese abilit ies and alt er one’s mot ivat ions.

Freedom, possibility and rationality 12.16 Even if behavioural genet ics is not an inherent ly f at alist doct rine, t here remain ot her w ays in w hich it can appear t o pose a t hreat t o t he not ion of a sense of responsibilit y. One f amiliar argument st art s f rom t he t hesis t hat someone w ho act s of t heir ow n f ree w ill, and is t heref ore responsible f or t heir act ions, is someone w ho ‘could have done ot herw ise’. If t heories in behavioural genet ics imply t hat t here are import ant respect s in w hich one could not have act ed ot herw ise, namely, w here one’s act ions w ere det ermined by genet ic disposit ions, it seems t o f ollow t hat t here is a conf lict bet w een responsibilit y f or oneself on t he one hand and behavioural genet ics on t he ot her. 12.17 In this case, the type of genetic determinism involved does not have to be the fatalist type already discussed and reject ed (paragraphs 12.10–12.15). Inst ead, t he more insidious suggestion is that although one’s choices do make a difference to the course of one’s life, the

8

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Phenylalaninehydroxylase (PAH) gene.

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GEN ETI CS, FREED O M A N D H U M A N D I GN I TY

12.19 A much bet t er response t o t he argument above is t hat it rest s on an illusion: it invokes a concept ion of f ree w ill as being a capacit y t o act ot herw ise w hich is complet ely ext ernal t o, and uncondit ioned by, one’s nat ural const it ut ion. Hence it is t he argument ’s st art ing-point w hich should be reject ed: t hat someone w ho act s of t heir ow n f ree w ill is someone w ho could have act ed ot herw ise. Inst ead, t he sensible posit ion t o t ake is t hat one act s of one’s ow n f ree w ill w hen, f irst , one’s act ion is t he out come of one’s choice, and, secondly, t his choice is it self t he out come of one’s deliberat ions regarding w hat t o do. What mat t ers as f ar as act ing of one’s ow n f ree w ill is concerned is t he involvement of one’s rat ional deliberat ions in t he causat ion of one’s act ions, and not t he exist ence, or not , of an abst ract possibilit y of act ing ot herw ise.

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12.18 One obvious response t o t his argument is just t o deny t hat behavioural genet ics, and indeed genet ics generally, support t he det erminist ic hypot hesis in quest ion, since, as t he earlier chapt ers show, genet ic evidence is likely t o generat e only predict ions of a st at ist ical nat ure; f or example, t hat A is t w ice as likely as B t o behave in a part icular w ay. But f or t w o reasons t his response is not sat isf ying by it self . First , as f ar as t he implied t hreat t o t he not ion of responsibilit y is concerned, it is not suff icient t o dismiss t he challenge t o responsibilit y t o say t hat genes are not ent irely det erminist ic; f or if t he inf luence of early environment and ot her f act ors is t aken int o account , it may st ill be possible t o get a considerably more robust , if not f ully det erminist ic, connect ion bet w een genet ic and environment al f act ors, and one’s behaviour. If t his w ere t rue, genet ics might t urn out t o be a major component in a det erminist ic science of behaviour. Secondly, it scarcely seems much of a def ence of t he not ion of responsibilit y t o rely on t he presence of chance element s in t he processes of human lif e. Responsible conduct seems even less like a merely chance occurrence t han a det ermined course of event s.

CH A PTER

fact that this capacity for choice, and the choices one makes, are themselves genetically determined in important respects shows that one is ultimately just a product of external forces, namely genes and the environment, and for this reason one lacks responsibility for oneself.

12.20 Thus, f reedom of act ion requires t hat one’s reasons play a causal role in w hat one does. Once t his is properly underst ood t he t hreat of det erminism f alls aw ay as irrelevant and it is not necessary t o pursue f urt her t he quest ion as t o how f ar behavioural genet ics implies det erminism. Inst ead, t here is a diff erent quest ion t hat needs t o be f aced, namely w het her an underst anding of human lif e t hat accept s t hat genet ic f act ors cont ribut e t o behavioural predisposit ions undermines t he involvement of t he reasoning of people in an explanat ion of t heir behaviour. In t he next sect ion, w e consider t hree philosophical approaches t o t his quest ion: eliminat ivism, f unct ionalism and rat ionalism. Box 12.1 provides a short summary of t he dist inguishing f eat ures of each approach.

Eliminating rationality 12.21 One inf luent ial cont emporary view t o t he eff ect t hat behavioural genet ics undermines t his concept ion of f ree w ill rest s on t he t hesis t hat t he underst anding of human lif e t hat is provided by genet ics and t he neurocognit ive sciences is incompat ible w it h our everyday underst anding of a person as a rat ional being, capable of t hinking and act ing f or reasons. The incompat ibilit y is supposed t o arise f rom t he f act t hat our ordinary underst anding of t hought and act ion involves an inescapable element of subject ive, personal int erpret at ion w hich cannot be combined w it h t he object ive, impersonal explanat ory schemes of t he nat ural sciences. For t his reason, some philosophers have argued t hat t his ordinary self underst anding is only a preliminary ‘f olk-psychology’, t o be progressively ‘eliminat ed’

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f rom descript ions of behaviour (and t he rest of realit y) as t he neurocognit ive sciences progress, in much t he w ay in w hich ‘f olk-ast ronomical’ ref erences t o sunrise and sunset linger on only as a harmless reminder of past belief , since w e now know t hat t he sun does not act ually ‘rise’ or ‘set ’.9 12.22 This is not t he place f or a det ailed crit ical appraisal of t his eliminat ivist posit ion; but t w o point s can be made brief ly concerning it . First , even if some element of subject ivit y is essent ial f or f orming an init ial underst anding of ot hers, it does not f ollow t hat t he result ing underst anding cannot be correct ed and ref ined as f urt her evidence is collect ed, unt il it becomes closer t o t he kind of object ivit y t hat is charact erist ic of t he nat ural sciences. Secondly, alt hough t here are areas of vagueness and imprecision in ordinary w ays of underst anding t hought and act ion, it does not f ollow t hat behavioural genet ics and ot her neurocognit ive sciences provide w ays of t hinking w hich should displace t his ordinary self underst anding. Inst ead, it is arguable t hat one should get used t o t he idea t hat human lif e just is vague and imprecise in some respect s.

Accommodating rationality 12.23 The obvious alt ernat ive t o t he eliminat ivist posit ion is t he view t hat t here is no incompat ibilit y bet w een t he underst anding of human lif e suggest ed by genet ics and t he neurocognit ive sciences and t he ordinary underst anding of people as beings capable of t hinking and act ing f or reasons. There are, how ever, t w o main w ays in w hich t his alt ernat ive has been developed; by support ers of f unct ionalist and rat ionalist posit ions respect ively. Support ers of a f unct ionalist posit ion argue t hat t he ordinary psychological concept ions of f ree w ill and responsibilit y ref er essent ially t o t he roles of physical st at es of t he brain. The det ailed operat ions of t hese st at es are t o be explained by t he neurocognit ive sciences in w ays w hich largely t ally w it h common sense belief s. Thus, t he f unct ionalist argues t hat t hese scient if ic t heories w ill event ually show how t hought s and mot ivat ions, t he t erms by w hich human lif e is normally underst ood, are ‘realised’, or implement ed, w it hin human beings. 12.24 Behavioural genet ics f it s int o t his f unct ionalist posit ion as a science w hich cont ribut es t o t he diff icult , but essent ial, t ask of charact erising t he basis, genet ic and neural, of behavioural disposit ions. Thus, f or t he f unct ionalist , t here is no incompat ibilit y bet w een t he f indings of behavioural genet ics and t he concept ion of oneself as a person capable of act ing of one’s ow n f ree w ill; on t he cont rary, t he behavioural genet icist makes an essent ial cont ribut ion t o underst anding w hat it is about human beings t hat gives t hem t his capacit y. 12.25 A cent ral f eat ure of t his f unct ionalist posit ion is t hat alt hough t he validit y of rat ional explanat ions of t hought and act ion is endorsed, any such explanat ion depends on t he exist ence of connect ions at t he level of t he neural st at es w hich implement t he t hought s and act ions involved. Thus explanat ions of t hought and act ion in w hich t he agent ’s reasons play some part are t hemselves argued t o be reducible t o t hose branches of t he neurosciences w hich do not recognise concept s such as ‘reason’, ‘decision’ and ‘f ree w ill’. In ot her w ords, t hese ordinary concept s can be f ully explained in t erms of neuroscience. 12.26 It is t his reduct ive t hesis w hich is reject ed by proponent s of t he rat ionalist posit ion. According t o t he rat ionalist , t he best w ays of underst anding t hose aspect s of human lif e in

9

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For a clear exposit ion of t his posit ion, see St ich, S. (1983). From Folk Psychology t o Cognit ive Science. Cambridge, M A: M IT.

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GEN ETI CS, FREED O M A N D H U M A N D I GN I TY

12.28 The result ing debat e bet w een f unct ionalist s and rat ionalist s is a t ransf ormed, and much improved, version of t he old debat es about det erminism and f ree w ill. In eff ect , t he quest ion of reduct ionism (w hich can be seen as a quest ion of explanat ion) replaces t he old misguided quest ion of det erminism (w hich is concerned w it h causat ion). Funct ionalist s hold t hat reduct ionism, t hat is, an explanat ion of behaviour in physical t erms, is compat ible w it h our ordinary underst anding of f ree w ill and responsibilit y. Rat ionalist s reject t his claim and aff irm t hat rat ional explanat ions of human aff airs cannot be reduced t o explanat ions in t erms of t he nat ural sciences (see Box 12.1).

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12.27 In reject ing t he f unct ionalist posit ion, rat ionalist s agree w it h eliminat ivist s t hat t here is somet hing dist inct ive about t he ordinary underst anding of t hought and act ion. But rat ionalist s disagree w it h eliminat ivist s in t hinking t hat t he nat ural sciences alone provide a f ramew ork f or underst anding t he w orld. Inst ead, rat ionalist s argue t hat human lif e is normally best underst ood by ref erence t o t he t hought s and f eelings of t hose involved in t hem, even if t here is somet hing inherent ly personal in t his kind of underst anding. Rat ionalist s reject , how ever, t he implicat ion t hat t his personal dimension in t he ordinary underst anding brings w it h it a ‘subject ive’ dimension t hat is inherent ly def ect ive w hen compared w it h t he object ivit y of t he nat ural sciences. They argue t hat it is t he charact erist ic mist ake of t hose w ho are over-impressed by t he nat ural sciences t o t hink t hat a properly object ive underst anding can be arrived at only w hen it is f ramed in t he impersonal concept s of t he nat ural sciences.10

CH A PTER

w hich one is engaged as a rat ional subject and a f ree agent are t o be f ound in explanat ions w hich are couched in t erms of t he implicat ions of one’s t hought s, f eelings, decisions and so on. These explanat ions are connect ed t o t he explanat ions of such f act ors as limb movement s, neural changes, and genet ic predisposit ions, t hat are provided by sciences such as physiology, genet ics and biochemist ry. For t he rat ionalist , behavioural genet ics belongs here as a w ay of making some of t hese connect ions. But t he rat ionalist denies t hat t hese connect ions bring w it h t hem t he t rue explanat ion of behaviour; in ot her w ords, t he suggest ion t hat t he exhaust ive and exclusive explanat ion of w hat happens is t o be f ound at t he level of biochemist ry.

Box 12.1: Folk psychology and natural science The cent ral point at issue bet w een eliminat ivist s (paragraphs 12.21–12.22), f unct ionalist s (paragraphs 12.23–12.25) and rat ionalist s (paragraphs 12.26–12.27) concerns t he relat ionship bet w een our f amiliar or common-sense underst anding of human t hought s and act ions, w hich draw s on an individual’s reasons, belief s and desires (and w hich is t ermed, in t hese debat es, f olk psychology) and t he kinds of explanat ion provided by t he nat ural sciences. Eliminat ivist s hold t hat t hese t w o approaches are incompat ible, and t hat event ually, f olk psychology w ill be eliminat ed as genet ics and t he neurocognit ive sciences develop. For example, t oday, our f olk psychology explanat ions of behaviour ref er t o t he belief s w e have. Eliminat ivist s maint ain t hat as cognit ive science progresses, ref erence t o belief s w ill be replaced by ref erence t o ment al represent at ions ident if ied purely as int ernal st at es of t he brain, lacking any ref erence t o t he w orld. Funct ionalist s deny t hat t here is any incompat ibilit y here: t hey argue t hat belief s may w ell t urn out t o be st at es of t he brain, but

10

For a classic st at ement of a rat ionalist posit ion of t his kind, see St raw son, P. F. (1974). Freedom and resent ment . In Freedom and Resent ment and Ot her Essays. London: M et huen.

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t hat does not show t hat our ordinary underst anding of belief s is incorrect . Thus, according t o t he f unct ionalist , f olk psychology needs t o be supplement ed in order t hat it s explanat ions can be vindicat ed; but t here is no reason t o hold t hat t his supplement at ion w ill lead t o t he radical undermining of f olk psychology ant icipat ed by t he eliminat ivist . Finally, rat ionalist s deny t hat f olk psychology needs t o be vindicat ed by being supplement ed in t his w ay. Like eliminat ivist s, rat ionalist s believe t hat f olk psychology has dist inct ive f eat ures w hich imply t hat it cannot be reduced t o t he nat ural sciences. But , unlike eliminat ivist s, rat ionalist s hold t hat t he dist inct iveness of f olk psychology is compat ible w it h t he nat ural sciences since t hey reject t he assumpt ion t hat everyt hing can be explained w it hin t he f ramew ork of t he nat ural sciences. One can summarise t his debat e as f ollow s:

Folk psychology provides a valid w ay of underst anding human lif e

Folk psychology cannot be explained by, or reduced t o, nat ural science

Everyt hing about human lif e can be explained w it hin t he f ramew ork of t he nat ural sciences

Eliminat ivist s

Disagree

Agree

Agree

Funct ionalist s

Agree

Disagree

Agree

Rat ionalist s

Agree

Agree

Disagree

The implications of behavioural genetics 12.29 There is no denying t hat t he scient if ic approach f ollow ed by most proponent s of behavioural genet ics f it s more readily int o a f unct ionalist posit ion t han a rat ionalist one. Equally t here is no denying t hat t he ordinary sense of responsibilit y f or oneself f it s bet t er w it h t he rat ionalist posit ion. Debat e regarding t he t w o posit ions cont inues, and it w ould be surprising if research in behavioural genet ics alone yielded any decisive implicat ions f or t his long-running debat e bet w een t hese t w o images of human beings. 12.30 It is nonet heless w ort h t rying t o clarif y t he signif icance, in ot her respect s, of behavioural genet ics f or t he underst anding of human behaviour. Remarks such as t hat ‘t here is a signif icant genet ic inf luence on divorce’,11 suggest t hat researchers in behavioural genet ics see t hemselves as able t o off er explanat ions of cult ural phenomena such as divorce. But t his is at best misleading: behavioural genet ics is f undament ally a branch of biochemist ry and biochemist ry know s not hing of marriage and divorce. For t his reason, scept ics argue t hat behavioural genet ics can have lit t le signif icant t o say about human lif e, since most of w hat mat t ers is cult urally def ined, and biochemist ry says not hing direct ly about cult ure.12

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11

M uir, H. (2001). Divorce is w rit t en in t he DNA. New Scient ist 12 July. See also M cGue, M . & Lykken, D. T. (1992). Genet ic inf luence on divorce. Psychol. Sci. 3, 368–73; Jockin, V. & M cGue, M . (1996). Personalit y and t he inherit ance of divorce. J. Pers. Soc. Psychol. 71, 288–99.

12

See f or example Rose, S. (1998). Lif elines. London: Penguin.

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FREED O M A N D H U M A N D I GN I TY

12.34 Indeed, t he consist ency of t hese t w o perspect ives st art s f rom t he f act t hat rat ional t hought and act ion presuppose abilit ies and capacit ies w hich are not t hemselves rat ionally grounded. Human act ion requires t he capacit y t o appreciat e reasons and t he abilit y t o act upon t hem, w hich are bot h ant ecedent t o reason.13 But t he abilit ies and personalit y t rait s w it h w hich one is endow ed, as a result of one’s genes and one’s environment , are not unalt erable. They normally include a capacit y f or self -development and self -crit icism t hrough t he very underst anding of oneself and t he w orld w hich t hey t hemselves make possible. It is only by unconsciously adhering t o a f at alist myt h t hat behavioural genet ics and t he psychology of personalit y can be regarded as inherent ly undermining one’s responsibilit y f or one’s ow n charact er.

GEN ETI CS,

12.33 One area of special relevance t o t his hypot hesis is t he f ield of t heories of personalit y. As t he review of research on personalit y indicat es (see Chapt er 8), t heories of personalit y post ulat e some basic t rait s: Eysenck’s Three (Neurot icism, Int roversion/ Ext raversion, Psychot icism), or t he Big Five (t he f irst t w o of Eysenck’s t rait s plus Conscient iousness, Openness and Agreeableness). The ident it y of t hese t rait s might w ell be t hought t o be t oo cult urally-specif ic f or t heir int ended role (indeed, t hey sound like t w ent iet h cent ury versions of t he old Four Humors), but it is not necessary here t o assess how f ar a complet ely cult urally neut ral t heory of personalit y is conceivable. For on any sensible view of t he mat t er, bot h genes and t he early environment play a part in f ixing t he paramet ers f or personalit y t rait s; w hat is import ant in t he present cont ext is just t hat t here is no inconsist ency bet w een t his hypot hesis and t he t hesis t hat social cult ure and individual rat ionalit y also shape one’s lif e.

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12.32 But w hat are t he relevant ‘mat erials’ and ‘st ruct ures’? One hypot hesis, speculat ive but plausible, is t hat genes give rise t o cert ain basic neural capacit ies w hich const it ut e an individual’s ‘int ermediat e phenot ype’ (see paragraph 3.15) and cont ribut e (along w it h environment al condit ions) t o t he f ormat ion of all t he more specif ic abilit ies w hich const it ut e t hat individual’s phenot ype as charact erised by ref erence t o ‘behaviour w it hin t he normal range’.

CH A PTER

12.31 But t his scept ical t hesis is t oo st rong. Here is a comparison: because physics says not hing direct ly about t ables and chairs, t here is not hing t o be learnt f rom physics about how t hey are const ruct ed. This inf erence is invalid. Physics has implicat ions f or t he underst anding of mat erials and st ruct ures, and t hese have obvious implicat ions f or t he const ruct ion of t ables and chairs. So if behavioural genet ics can t ell us about t he ‘mat erials’ and ‘st ruct ures’ of human lif e, t hen it w ill have implicat ions f or t he underst anding of human lif e, including cult ural phenomena about w hich it does not speak direct ly.

12.35 This rat her abst ract argument may appear excessively complacent . For t here are of course people w it h personalit y disorders w hich make it pract ically impossible f or t hem, even w it h psychiat ric help, t o t ake much cont rol of t heir lives. But t he f act t hat in some cases people suff er f rom t hese disorders does not show t hat behavioural genet ics implies t hat t he same inabilit y t o exercise cont rol is t rue of everyone. M oreover, t his can be t rue w het her t he causes of personalit y disorder are primarily genet ic (as appears t o be t he case f or schizophrenia) or environment al (as in t he case of vict ims of abuse during childhood).

13

One is, in Heidegger’s phrase (Heidegger, M . (1927). Sein und Zeit . Verlag, Tubingen: M Niemayer), ‘t hrow n’ by one’s genes and early environment int o t he space of reasons (Sellars, W. (1963). Empiricism and t he philosophy of mind. In Science, Percept ion and Realit y. London: Rout ledge and Kegan Paul. p. 169). One does not arrive t here by one’s ow n eff ort s.

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Behavioural genet ics, like medical science generally, implies t hat t here are only diff erences of degree bet w een ‘illness’ and ‘healt h’. This implies t hat responsibilit y comes in degrees, but not t hat no one is t ruly responsible f or t heir lives; diff erences in colour and t ast e are of t en, af t er all, ‘only’ diff erences of degree, but t his does not show t hat diff erences of colour and t ast e are t heref ore unimport ant . 12.36 It is impossible t o read st udies of ident ical t w ins w it hout being impressed by t he anecdot al t ales of similarit ies and diff erences in t he t ast es and habit s of t hose w ho w ere reared f ar apart .14 But t hese t ales do not describe people w ho are mere puppet s; inst ead t hey describe people w hose lives exemplif y t he unique synt hesis t hat heredit y, environment and opport unit ies help one make of oneself . A person’s charact er is not t he f abled ‘t abula rasa’ (or blank sheet of paper). The w rit ing on t he paper st art s w it h one’s genes and early environment . But , t o varying degrees, t hese early inf luences also enable one t o w rit e more, and crucially, t o erase, f or oneself .

Conclusion 12.37 The aspect of human dignit y t hat has been cent ral t o t his chapt er is t he concept ion of oneself as a f ree responsible agent , capable of act ing f or reasons and direct ing t he course of one’s lif e in accordance w it h one’s ow n values and underst anding of t he w orld. This does not exhaust t he et hical cont ent of t he concept ion of human dignit y, but it is a cent ral component of it : t o argue t hat t he concept ion of oneself and ot hers as responsible individuals is misplaced w ould be t o reject one of t he main reasons w e have f or holding t hat each person’s lif e is int rinsically valuable in so f ar as it expresses t hat person’s ow n, unique, perspect ive. 12.38 It has been argued t hat w hen t he issues are correct ly underst ood, t here is no inherent conf lict bet w een a great er underst anding of genet ic cont ribut ions t o behaviour and due regard f or human dignit y. A non-reduct ive, rat ionalist , underst anding of human f reedom can coexist w it h recognit ion of t he genet ic inf luences on our human abilit ies, capacit ies and mot ivat ions, even t hough a reduct ive, f unct ionalist , account f it s more readily alongside t he scient if ic perspect ive employed by behaviour genet icist s. It is not necessary here t o t ake a st and on t his debat e. But any sensible underst anding of human f reedom and dignit y must allow f or some st art ing-point in t he development of t he abilit ies w hich are cent ral t o t his f reedom and dignit y. Behavioural genet ics promises t o elucidat e t his st art ing-point , and t hereby cont ribut e t o t he underst anding of humanit y. But it no more off ers a complet e t heory of human behaviour t han does any ot her single scient if ic discipline. Thus, t here is no reason f or adherent s of behavioural genet ics, or crit ics, t o regard it as off ering a radically new w ay of underst anding human lif e w hich t hreat ens t o undermine t he dignit y of humanit y. It complement s, and does not displace, t he f amiliar social sciences, t he humanit ies and indeed our ordinary underst anding of behaviour.

14

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Segal, N. (2000). Ent w ined Lives: Tw ins and What They Tell Us About Human Behavior. New York: Plume.

Chapter Select ing and changing behavioural t rait s

13

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Introduction

BEH AV I O U RA L TRA I TS

13.4 A second response is t o consider t he available evidence in t he f ield of research in behavioural genet ics and t o t ry t o make realist ic predict ions about w het her it w ill lead t o pract ical applicat ions. As w e not ed in Chapt er 11, it is clear t hat , current ly, very f ew individual genes t hat inf luence human behavioural t rait s in t he normal range have been ident if ied. Despit e t his, w e need t o keep in mind t hat in t he f ut ure it may become possible t o make predict ions, albeit limit ed ones, about behaviour, based on genet ic inf ormat ion and t o design usef ul applicat ions of t his know ledge.

CH A N GI N G

13.3 One response t o t his challenge is t hat it does not exempt us f rom considering anxiet ies aroused by popular belief s in t his area, even if t hese belief s t urn out t o be misconcept ions. In t he past , social policies, f or example eugenic policies, have been built on minimal, or erroneous, scient if ic f oundat ions. M ore recent ly, misunderst andings about genet ics have led t o unw arrant ed discriminat ion: t he US Nat ional Sickle Cell Anemia Cont rol Act of 1972 led t o t he unjust if ied discriminat ion and st igmat isat ion of Af rican Americans in educat ion, employment , insurance and t he grant ing of licences t o adopt and marry.1

A N D

13.2 Bef ore w e begin, how ever, w e need t o conf ront a scept ical challenge, t o t he eff ect t hat t hese ref lect ions serve no usef ul purpose. The basis of t his challenge is t hat , w hile everyone accept s t hat genes have an impact on behaviour, genet ic t est s w ill have a low predict ive capacit y because of t he myriad ot her f act ors t hat inf luence our behaviour and t he vast ly complex int eract ions bet w een genet ic f act ors t hemselves. Hence, t he challenge runs, if t he w orkings of t he many genes involved in behaviour are so complex t hat it is impossible t o make any robust predict ions based on genet ic t est s, or t o design any eff ect ive int ervent ions as a result of t hem, t here is no point in discussing t he et hics of t heir applicat ion.

SELECTI N G

Will there be any practical applications of research in behavioural genetics?

1 3

13.1 In t he next t hree chapt ers, w e consider some of t he quest ions t hat may arise if w ays of ident if ying genet ic inf luences on t he t rait s or charact erist ics of an individual could be developed. In t his chapt er, w e consider w het her t here are reasons f or choosing cert ain t ypes of int ervent ion t o select or change t he t rait s and charact erist ics of individuals, bot h bef ore and af t er birt h. In Chapt er 14 w e assess w het her research in behavioural genet ics ought t o change our concept ion of legal responsibilit y and t he w ay in w hich w e t reat t hose w ho break t he criminal law. In Chapt er 15, w e discuss t he use of genet ic t est ing f or behavioural t rait s in t he cont ext s of employment , educat ion and insurance.

CH A PTER

Selecting and changing behavioural traits

13.5 Hence, w hile it is cert ainly t oo early t o discuss det ailed applicat ions of behavioural genet ics, w e need t o conf ront anxiet ies based on current belief s about t his subject . As Barbara Kat z Rot hman has argued, t here is reason t o consider t hese possibilit ies now : ‘The scient ist s quickly speak up: t hat isn't possible, t hey reassure us, you don't underst and t he genet ics involved. Five years lat er, of course, t hat is possible, and t hen it is t oo lat e t o decide w het her or not t o do it : w e w ake up t o f ind it done.’ 2

1

Serjeant , G.R. (1985). Sickle Cell Disease. Oxf ord: Oxf ord Universit y Press.

2

Kat z Rot hman, B. (1998). Genet ic M aps and Human Imaginat ions. New York: WW Nort on. p. 37.

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13.6 As inf ormat ion about genet ic inf luences on behaviour in t he normal range is acquired, w ays of changing t he t rait s in quest ion may also be developed. Such int ervent ions could t ake one of t hree diff erent f orms: genet ic manipulat ion; t he use of medicines; or changes t o t he individual’s environment . In t his chapt er, w e w ill ref er t o t hese t hree cat egories as ‘genet ic int ervent ions’, ‘medical int ervent ions’ and ‘environment al int ervent ions’. In discussing t hese, w e also dist inguish int ervent ions w hich t ake place bef ore birt h f rom t hose w hich occur lat er in lif e. We consider t he issues raised by prenat al select ion in paragraphs 13.57 – 13.78 below.

Genetic interventions 13.7 Genet ic int ervent ions can be of t w o t ypes, depending on t he cells in t he body t o w hich t hey are applied. Somat ic gene t herapy is t he process of changing t he genot ype of an individual by modif ying t he DNA in t he cells of t heir body. This t ype of t herapy is current ly being st udied as a pot ent ial cure f or genet ic disorders such as haemophilia and cyst ic f ibrosis. The aim is t o replace, in t he relevant part s of t he body, t he mut at ed DNA t hat causes t he disease. For example, a person w it h cyst ic f ibrosis might receive gene t herapy t hat w as t arget ed at t he lungs. An individual w ho has received t his t ype of gene t herapy w ould, how ever, be unlikely t o pass on t he genet ic changes t o his or her children, because t he t herapy w ould not aff ect t he cells t hat are import ant in reproduct ion, namely t he egg and sperm cells. 13.8 The second t ype of gene t herapy is called germline gene t herapy (it is also ref erred t o as germline genet ic engineering). This involves modif ying t he germline cells, t hose cells t hat are t ransmit t ed t o children by t heir parent s. Thus, germline gene t herapy w ould change not only t he charact erist ics of t he individual w ho received t he t herapy, but also t he charact erist ics of t heir children and f ut ure generat ions. There is a general consensus t hat , at present , t he consequences are not w ell enough underst ood f or t his procedure t o be at t empt ed saf ely, and t hus t hat germline gene t herapy should not current ly be at t empt ed.3 Indeed, t he Council of Europe (1997) Convent ion f or t he Prot ect ion of Human Right s and Dignit y of t he Human Being w it h Regard t o t he Applicat ion of Biology and M edicine: Convent ion on Human Right s and Biomedicine st at es in Art icle 13 t hat ‘an int ervent ion seeking t o modif y t he human genome may only be undert aken f or prevent ive, diagnost ic or t herapeut ic purposes and only if it s aim is not t o int roduce any modif icat ion in t he genome of any descendant s'.4 13.9 Genet ic int ervent ions are st ill at a preliminary st age even in t he comparat ively less complex case of single-gene disorders. The possibilit y of t heir use in alt ering complex t rait s is st ill f ar off , but as t he Report of t he Commit t ee on t he Et hics of Gene Therapy, present ed t o Parliament in 1992, observed: ‘We are alert t o t he prof ound et hical issues t hat w ould arise w ere t he aim of genet ic modif icat ion ever t o be direct ed t o t he enhancement of normal human t rait s’.5 (We consider t he possibilit y of somat ic and germline gene t herapy f or t rait s in t he normal range in paragraphs 13.31 – 13.32).

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3

See ‘Changing t he World’ in Harris, J. (1992). Wonderw oman and Superman. Oxf ord: OUP f or an int erest ing analysis of t he et hical argument s against germline gene t herapy.

4

Council of Europe (1997) Convent ion f or t he Prot ect ion of Human Right s and Dignit y of t he Human Being w it h Regard t o t he Applicat ion of Biology and M edicine: Convent ion on Human Right s and Biomedicine. ETS No: 164.

5

Commit t ee on t he Et hics of Gene Therapy (Chairman: Clot hier, C.). (1992). Report of t he Commit t ee on t he Et hics of Gene Therapy. London: HM SO; Cm 1788. p. 7, paragraph 2.16.

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6

See f or example Cent er on Hunger, Povert y and Nut rit ion Policy. (1995). St at ement on t he Link bet w een Nut rit ion and Cognit ive Development in Children. M edf ord, M A: Tuf t s Universit y School of Nut rit ion and M eyers; A. F. et al. (1989). School Breakf ast Program and school perf ormance, Am. J. Dis. Child. 143, 1234–9. Also, Ivanovic, D. M . I (2000). Long-t erm eff ect s of severe undernut rit ion during t he f irst year of lif e on brain development and learning in Chilean high-school graduat es. Nut rit ion 16, 1056–63.

7

See f or example St ein, J. et al. (2002). In harm's w ay: t oxic t hreat s t o child development . J. Dev. Behav. Pediat r. 23, S13–22 and Diet rich, K. N. I. (1993). The development al consequences of low t o moderat e prenat al and post nat al lead exposure: int ellect ual at t ainment in t he Cincinnat i Lead St udy Cohort f ollow ing school ent ry. Neurot oxicol. Terat ol. 15, 37–44.

8

Sure St art is a programme run by t he UK Government t hat aims t o improve t he physical, social and int ellect ual development of babies and young children so t hat t hey can f lourish at home and at school. It f ocuses on encouraging good healt h in f amilies w it h young children in deprived areas and on making available ot her f acilit ies such as early learning.

TRA I TS

13.13 Trait s such as sexualit y, aggression and int elligence have in t he past been t hought of as out comes of inherit ance, f amily background, socio-economic environment , individual choice and even divine int ervent ion. If research in behavioural genet ics ident if ies t he inf luence of genes on such t rait s, t hey may mist akenly come t o be t hought of as being f undament ally det ermined by genet ic f act ors and even as aspect s of lif e w hich belong t o one’s ‘f at e’ (see paragraphs 12.10 – 12.15). Indeed, being diagnosed as at risk of disease may have a t endency t o make healt hy people f eel ill, or f eel f at alist ic about t heir chances of survival, despit e t he exist ence of diet s, lif e-st yles or t reat ment s t o avoid t he development of disease. It is possible t hat inf ormat ion about genet ic f act ors t hat indicat e suscept ibilit y t o a disease may make people t hink t hat t he unw ant ed out come is

BEH AV I O U RA L

‘M edicalising’ human behaviour

CH A N GI N G

13.12 In paragraphs 13.26 – 13.48, w e consider w het her t here are good reasons t o pref er a part icular t ype of int ervent ion t o change behavioural t rait s, bot h at an individual level and w it h regard t o t he w ider communit y. Bef ore t hat , w e discuss t w o general concerns about t he consequences of applying f indings f rom research in behavioural genet ics – medicalisat ion and st igma – t hat apply more generally t o t he research it self and t he use of t est s, as w ell as t o pot ent ial int ervent ions t o change t rait s.

A N D

13.11 The t hird t ype of int ervent ion involves environment al st rat egies f or changing behaviour. We already have some clear examples of such int ervent ions. For example, it seems likely t hat improving t he diet and st andard of living of children also improves t heir IQ.6 There is also good evidence t hat exposure t o chemicals such as lead can adversely aff ect behavioural t rait s.7 Ot her social policies such as t he provision of f ree educat ion and schemes such as Sure St art 8 are specif ically premised on t he capacit y t o change or enhance various t rait s in t he populat ion.

SELECTI N G

Environmental interventions

1 3

13.10 It seems more likely t hat if new int ervent ions aimed at changing behavioural t rait s in t he normal range are developed as a result of research in behavioural genet ics, t hey w ill t ake t he f orm of drugs, or of environment al int ervent ions such as changes in diet or in social policies. M edical int ervent ions such as ant i-depressant drugs and drugs t hat claim t o alleviat e shyness are already in use, and it may be t hat addit ional drugs w ill be developed t hat can alt er normal behaviour. Predict ions t hat t here w ill be drugs t o enhance our memories, improve our cognit ive f unct ion, or change our personalit ies are of t en made w hen scient ist s, journalist s and ot her comment at ors speculat e on f ut ure advances. Research in behavioural genet ics might lead in t his direct ion by suggest ing w hich genes might be t he best t arget s f or new drugs.

CH A PTER

M edical interventions

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inevit able.9 It has been suggest ed, t hat t he w ord ‘genet ic’ is int erpret ed as synonymous w it h somet hing f ixed or unchanging in West ern cult ure, w hen it is used in relat ion t o disease.10 Wit h regard t o behavioural t rait s, t heref ore, inf ormat ion about genet ic suscept ibilit y might engender similarly f at alist belief s. 13.14 As t he review s of t he evidence indicat e, f at alism about genet ics is a misconcept ion. Even w hen behavioural t rait s are inf luenced by genes, t here are alw ays ot her inf luences, and t he exist ence of genet ic inf luences does not show t hat w e are pow erless t o change or modif y our charact er: ‘scient ist s may w ell ident if y an allele t hat causes a genet ic predisposit ion t o shyness, but such a discovery does not mean t hat shyness cannot be overcome.’ 11 Nonet heless, t his misconcept ion is pervasive and gives rise t o t he anxiet y t hat behavioural genet ics w ill lead t o t he ‘medicalisat ion’ of t hose w ho are f ound t o be genet ically predisposed t o cert ain behavioural t rait s. 13.15 At t he root of concerns about medicalisat ion is t he idea t hat behavioural t rait s t hat have previously been regarded as ‘normal’ w ill come t o be view ed as ‘abnormal’ or pat hological. In addit ion, behavioural t rait s w it hin t he normal range may t urn out t o be amenable t o inf luence by pharmacological int ervent ions as a result of know ledge about t he biological f act ors t hat aff ect t hem. Concerns about medicalisat ion have been expressed f or many decades, f or example in relat ion t o t he increasing number of psychiat ric condit ions t hat are recognised, and in t he increasing use of medicines. In t he era of genet ic research, t he f ear is t hat t he ident if icat ion of t he inf luences of genes w ill exacerbat e t his t rend, encouraging t he re-classif icat ion of behavioural t rait s as w it hin t he realm of medicine. 13.16 In some cases genet ic research may indicat e t hat a behavioural t rait is one f or w hich medical int ervent ions are appropriat e and w elcome. Findings f rom research concerning t he biological basis of addict ion t o alcohol, and of aut ism, helped t o liberat e individuals and parent s f rom t he charges previously laid against t hem of moral w eakness and of neglect ing t heir children respect ively. In such cases, it should be acknow ledged t hat t his ‘medicalising’ t endency is benef icial: t he research helps t o conf irm t he view t hat t he individuals concerned should be perceived as ill, rat her t han bad, and in need of medical help, rat her t han discipline and punishment .12 13.17 How ever, in ot her cases, medicalisat ion may have adverse eff ect s. One such problem is t hat of diagnost ic spread, or t he t endency f or disorders t o be broadly def ined so t hat more and more individuals are caught in t he diagnost ic net . This t endency may arise as a result of an erroneous assumpt ion t hat once a biological inf luence on a t rait has been ident if ied, t he t rait becomes t he proper subject of medical int ervent ion. Or, it may be t hat if medicines are developed t hat have an eff ect on a t rait , t hat t rait w ill come t o be seen as a disorder, or somet hing t o be t reat ed and alt ered.

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9

Senior, V., M art eau, T. M . & Weinman, J. (1999). Impact of genet ic t est ing on causal models of heart disease and art hrit is: an analogue st udy, Psychol. Healt h 14, 1077–88.

10

M art eau, T. M . & Senior, V. (1997). Illness represent at ions af t er t he human genome project : t he perceived role of genes in causing illness. In Pet rie, K. J. & Weinman, J. A., edit ors. Percept ions of Healt h and Illness: Current Research and Applicat ions. Reading, UK: Harw ood Academic Publishers. pp. 241–66.

11

Rot hst ein, M . A. (2000). Genet ics and t he w ork f orce of t he next hundred years. Columbia Bus. Law Rev. 2000 (3), 371–401 at p. 383.

12

See f or example Conrad, P. & Schneider, J. W. (1992). Deviance and M edicalisat ion: From Badness t o Sickness. Philadelphia: Temple Universit y Press.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

TRA I TS

3. Would you say your anxiet y or w orry int erf eres w it h your w ork, f amily or social lif e?

BEH AV I O U RA L

Feeling rest less, keyed-up, or on edge? Feeling t ense? Feeling t ired, w eak, or easily exhaust ed? Having diff icult y concent rat ing? Feeling irrit able? Having diff icult y sleeping?

CH A N GI N G

-

A N D

2. Are you of t en bot hered by t he f ollow ing:

SELECTI N G

1. Do you w orry excessively or are you anxious a lot of t he t ime?

1 3

13.19 Similarly, t he producers of new ‘ant i-shyness’ drugs, such as Paxil and Luvox, have been accused of applying t o normal behaviour, int ervent ions developed f or pat hological t rait s.13 Paxil is licensed in t he US f or t he t reat ment of depression, Social Anxiet y Disorder (SAD), Generalised Anxiet y Disorder (GAD),14 Obsessive Compulsive Disorder, Panic Disorder and Post -t raumat ic St ress Disorder. The Paxil w ebsit e not es t hat approximat ely 10 million adult s are diagnosed w it h GAD each year in t he US.15 The w ebsit e encourages individuals t o t ake an online ‘self -t est ’ f or GAD, w hich involves answ ering t hree quest ions:

CH A PTER

13.18 An example of t his lat t er phenomenon is t he prescript ion of met hylphenidat e (Rit alin) t o children w it h At t ent ion Def icit Hyperact ivit y Disorder (ADHD). This example is cont roversial because t here are undoubt edly some children w ho have serious behavioural problems and w ho benef it great ly f rom t he drug. It w ould be w rong t o suggest t hat ADHD has been invent ed; indeed, t he condit ion has been recognised f or many decades. How ever, t he advent of medicines t hat are ef f ect ive in improving concent rat ion and reducing hyperact ivit y is a f airly recent development . In 1999, t he US Nat ional Associat ion of St at e Boards of Educat ion est imat ed t he number of children t aking Rit alin on a daily basis at bet w een 1.3 and 2 million. The Nat ional Inst it ut es of Healt h in t he US has recent ly undert aken a st udy t o examine prescribing pract ices.

Answ ering ‘yes’ t o more t han 1 of t he complaint s list ed in quest ion 2, even if t he answ ers t o quest ions 1 and 3 are negat ive, is suff icient t o generat e a response t hat says t he result s are inconclusive and suggest s discussing t hem f urt her w it h a healt h prof essional. 13.20 A similar self -t est can also be undert aken f or SAD, t he key sympt oms of w hich are a persist ent f ear of and an associat ed avoidance of social sit uat ions involving st rangers. In an art icle in t he New York Times M agazine about SAD, one comment at or observed: ‘unt il recent ly, it w as t hought t o be a rare disorder ... Then in 1999, buoyed by t he success of t he new psychot ropic drugs, t he pharmaceut ical company Smit hKline Beecham began market ing it s ant idepressant Paxil as a t reat ment f or social phobia …

13

See f or example Koerner, B. I. (2002). First , you market t he disease…t hen you push t he pills t o t reat it . The Guardian, (30 July). t aken f rom Koerner, B. I. Disorders made t o order. M ot her Jones magazine. July/August (2002).

14

GAD is psychiat ric disorder w hich f eat ures in t he t w o main classif icat ion syst ems f or ment al illness, t he Diagnost ic and St at ist ical M anual of M ent al Disorders, Fourt h Edit ion (DSM -IV) and t he ICD-10 Classif icat ion of M ent al and Behaviour Disorders.

15

ht t p://w w w.paxil.com (17 July 2002).

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Expert s cit ed alarming new st at ist ics – around 13% of us w ere socially phobic, f or example – and magazines dished up t he requisit e alarmist t rend st ories. A set of t rait s and behaviours, at least some of w hich w ere once regarded as neut ral, or even desirable, re-emerged as a pat hology – a f unct ion of brain chemist ry, amenable t o and indeed demanding pharmacological manipulat ion.’ 16 13.21 These examples can be view ed as illust rat ions of diagnost ic spread, t he re-classif icat ion of behavioural t rait s, and t he possibilit y of commercial and social pressure t o make use of medical int ervent ions. While t hese examples are not t he result of f indings in genet ic research, t hey demonst rat e t he exist ence of a t endency t ow ards medicalisat ion, and corresponding problems, t o w hich f indings in genet ics may cont ribut e. 13.22 A f urt her pot ent ial problem relat ed t o medicalisat ion is t he t endency t o f ocus excessively on t he biological f act ors t hat inf luence part icular t rait s, rat her t han t he social or economic f act ors. In paragraph 3.17, w e observed t hat t hose f act ors t hat are described as t he ‘cause’ of a part icular t rait are of t en t hose by w hich one hopes t o cont rol or alt er t hat t rait . Thus, t here is a risk t hat t he role of genet ic f act ors w ill be over-est imat ed, so t hat genet ic and medical int ervent ions can be provided, rat her t han f ocusing on t he social and economic environment s w hich are also likely t o play a vit al role. This may be so even t hough t here is no scient if ic reason f or assuming t hat if genet ic inf luences on a t rait are ident if ied t hat t rait w ill be easier t o alt er using medical or genet ic int ervent ions rat her t han ot her f orms. Examples of t his phenomenon include t he risk t hat medicines may be prescribed f or children w ho are disrupt ive but do not have a clinical diagnosis of hyperact ivit y, rat her t han invest igat ing ot her approaches such as reducing class sizes, and t hat medicat ion may be used rat her t han diet and exercise as st rat egies f or dealing w it h hypert ension or obesit y. 13.23 M edicalisat ion is an issue t hat aff ect s many areas of lif e, not just behavioural genet ics. In t he case of behavioural t rait s, since research int o genet ic inf luences is at an early st age, it is not possible t o say w het her medicalisat ion w ill be likely, or w het her it w ill have, on balance, posit ive or negat ive implicat ions. How ever, examples of t he delet erious eff ect s of medicalisat ion in ot her areas suggest t he need f or aw areness of pot ent ial problems. We conclude t hat research in behavioural genet ics has t he pot ent ial t o cont ribut e t o t he exist ing phenom enon of m edicalisat ion. Delet erious eff ect s t hat should be borne in m ind include shif t ing t he boundary bet w een norm al variat ion and disorder f urt her aw ay f rom t he ext rem es of variat ion; reducing social t olerance of previously ‘norm al’ behavioural t rait s; and t he rout ine select ion of genet ic or m edical int ervent ions w it hout adequat e considerat ion being given t o environm ent al int ervent ions and ot her opt ions. 13.24 Any discovery of biological mechanisms t hat inf luence behaviour, including genes, may aid in t he development of drugs w hich modif y behaviour. We consider t hat t here is pot ent ial f or t he unhelpf ul w idening of diagnost ic cat egories, t o encourage t he use of medicat ion by people w ho w ould not necessarily be t hought of as exhibit ing behavioural t rait s out side t he normal range. In addit ion t o t he pot ent ially harmf ul eff ect s already list ed, t his could lead t o unnecessary increased expendit ure by t he healt h service. We recom m end t hat

16

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Talbot , M . (2001). The shyness syndrome: bashf ulness is t he lat est t rait t o become a pat hology. New York Times M agazine 24 June.

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Stigma

CH A N GI N G BEH AV I O U RA L TRA I TS

‘Does your response t o someone you know is gay depend on know ing w hy he or she is gay? Should t he right t o live f ree of discriminat ion depend on a biological explanat ion of diff erence? M ost import ant ly, w ould f inding a biological explanat ion make any diff erence in t he w ay w e perceive ourselves and each ot her?’ †

A N D

Responses t o research int o genet ic inf luences on sexual orient at ion, in part icular t he w idely-publicised f indings of Hamer and Le Vay, varied great ly even w it hin t he lesbian and gay communit y.* M any gay and lesbian groups seemed keen t o capit alise on t he t rend, demonst rat ed in numerous opinion polls, t ow ards increased accept ance of homosexualit y if it is concept ualised as a biologically det ermined t rait , regardless of w het her or not t his w as show n t o be accurat e. How ever, ot hers w ere more scept ical:

SELECTI N G

Box 13.1: Public responses to genetic research into sexual orientation

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13.25 A rat her diff erent anxiet y arises f rom t he percept ion t hat t he use of genet ic t est s might increase social st igma and t endencies t ow ards t he labelling of people w ho display t he t rait s being t est ed. For example, claims t hat a genet ic predisposit ion t o homosexualit y has been ident if ied may give credence t o t he view t hat homosexualit y is pat hological, t hereby increasing t he st igmat isat ion of homosexuals, and leading t o pressure f or gay people t o be ‘cured’, and f or prenat al select ion against ‘gay’ f et uses. This is illust rat ed in Box 13.1 below, w hich illust rat es t he public response t o genet ic research int o sexual orient at ion t hat w as summarised in Chapt er 10. As Box 13.1 indicat es, know ledge of a genet ic predisposit ion may also help t o reduce t he st igma associat ed w it h a t rait by leading t o accept ance of it as ‘nat ural’.

CH A PTER

healt h service providers, and in part icular t he Depart m ent of Healt h, specif ically charge a nam ed agency w it h m onit oring and, if necessary, cont rolling, t his m eans of t he deliberat e m edicalising of norm al populat ions.

Out side t he gay communit y, most publicit y w as obt ained by t hose w ho view ed t he research as leading t o t he possibilit y of curing or eliminat ing homosexualit y. The Chief Rabbi at t he t ime spoke in f avour of using t he research in t his w ay, saying t hat w e may pract ise medical ingenuit y t o relieve suf f ering or a human disabilit y.‡ (Ot her Jew ish groups, including t he Union of Jew ish St udent s in Brit ain, vehement ly reject ed t he use of genet ic engineering or t erminat ion of pregnancy t o eliminat e homosexualit y.) In 1997, James Wat son published an art icle in a nat ional new spaper in w hich he proposed t hat w omen should be allow ed t o abort f et uses predisposed t ow ards homosexualit y w hich drew similar opposit ion f rom gay and lesbian groups, journalist s and ot her comment at ors.∫

*

See Chapt er 10 f or a discussion of t hese f indings.

†

PFLAG (Parent s, Families and Friends of Lesbians and Gays). (1995). Why ask Why? Addressing t he Research on Homosexualit y and Biology. (pamphlet ).

‡

Chief Rabbi Lord Jakobovit s, quot ed in Rose, H. Gay brains, gay genes and f eminist science t heory. In Weeks, J. & Holland, J., edit ors. (1996). Sexual Cult ures. Houndmills, Basingst oke: M acM illan.

∫

Langt on, J. (1997). The genie of t he gene. Sunday Telegraph. 16 February.

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Evaluating different w ays of changing ourselves 13.26 Despit e t hese concerns about medicalisat ion and st igma, w e consider t hat t here is, prima f acie, no reason f or pref erring one t ype of int ervent ion over anot her as a mat t er of principle. For any given t rait and any given individual, t he f act ors inf luencing t he development and expression of t hat t rait are likely t o be many and varied. In diff erent cases, t here may be reasons f or t hinking t hat diff erent f orms of int ervent ion are appropriat e. In t he next sect ion, w e consider f ive f eat ures of any int ervent ion t hat may provide moral reasons f or accept ing or reject ing t heir use, namely t he eff ect iveness, saf et y and reversibilit y of t he int ervent ion, t he ext ent t o w hich one can make choices about it s use, and it s implicat ions f or individualit y.

(i) Effectiveness 13.27 The eff ect iveness of genet ic int ervent ions, w hich w ould be most likely t o t ake t he f orm of gene t herapy, is diff icult t o predict . As w e not ed in Chapt er 3, and as t he review s of t he evidence ref lect , genes t hat inf luence behavioural t rait s in t he normal range are likely t o exert small individual eff ect s, w hich are likely t o depend on t he presence of ot her genes, as w ell as environment al f act ors. This means t hat , even if one could alt er t he expression of one or a f ew genes successf ully, it w ould by no means be cert ain t hat t he desired change in t he phenot ype w ould occur. 13.28 This is also likely t o be t rue of medical and environment al int ervent ions. Research in behavioural genet ics does not suggest t hat pharmacological int ervent ions are likely t o be universally successf ul any more t han environment al int ervent ions, such as changes in parent al care, diet , met hods of educat ion, social pressures, economic condit ions and so on. The f act is t hat predict ing t he likely eff ect iveness of diff erent t ypes of int ervent ion is a diff icult t ask. For example, many comment at ors have argued t hat if w e w ish t o enhance children's IQ scores, it is t heir environment rat her t han t heir genot ypes t hat w e should be seeking t o aff ect . But our ignorance of t he w ays in w hich genes aff ect IQ is mat ched only by our ignorance of how t he environment aff ect s IQ. It is clear t hat environment al changes must have cont ribut ed t o t he 20–30 point rise in scores on st andard IQ t est s t hat occurred in t he t w ent iet h cent ury (see Chapt er 7, f oot not e 3). But w e do not know w hich environment al changes. It seems probable t hat t here w ere a large number, each w it h a small eff ect (changes in nut rit ion and general healt h, diff erent st yles of educat ion, more emphasis on problem solving and more exposure t o sophist icat ed visual messages, have all been suggest ed). Furt hermore, t he belief t hat it w ill be a simple mat t er t o alt er t he environment in such a w ay as t o increase children's IQ scores is just as f allacious as t he converse belief t hat genet ic eff ect s are immut able. One int ervent ion t hat has been show n t o produce a subst ant ial increase in t he IQ scores of children living in povert y and neglect is t o have t hem adopt ed.17 But t his can hardly be t ranslat ed int o social policy.

(ii) Safety 13.29 At f irst glance, it might be t hought t hat environment al int ervent ions are t he saf est f orm of int ervent ion, in t he sense t hat t hey seem least likely t o have unpredict ed or undesirable consequences. How ever, it should be not ed t hat changes in an individual’s psychosocial environment can have adverse result s t hat persist t hroughout his or her lif e.

17

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Duyme M . et al. (1999). How can w e boost IQs of ‘dull children’?: a lat e adopt ion st udy. Proc. Nat l. Acad. Sci. USA 96, 8790–4.

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1 3 SELECTI N G A N D CH A N GI N G BEH AV I O U RA L TRA I TS

13.31 Genet ic int ervent ions current ly bring w it h t hem serious concerns about saf et y. The Unit ed Nat ions Educat ional, Scient if ic and Cult ural Organizat ion (UNESCO) Universal Declarat ion on t he Human Genome and Human Right s st at es in Art icle 5 t hat ‘Research, t reat ment or diagnosis aff ect ing an individual's genome shall be undert aken only af t er rigorous and prior assessment of t he pot ent ial risks and benef it s pert aining t heret o and in accordance w it h any ot her requirement of nat ional law '.18 The Clot hier Report on t he et hics of gene t herapy ident if ied a number of w ays in w hich gene t herapy might pose a risk t o saf et y.19 These included mist akes in insert ing t he correct ing gene, t he possibilit y t hat t he gene w ould be expressed in t he w rong place or at t he w rong t ime, t he possibilit y t hat insert ion of t he gene might cause a new mut at ion or genet ic disease, and t he possibilit y t hat t he correct ing gene might move f rom it s t arget locat ion in t he body and aff ect ot her cells. As a result , all applicat ions t o carry out t rials of gene t herapy in humans in t he UK are monit ored by t he Gene Therapy Advisory Commit t ee (GTAC). We consider t hat in view of t he risks inherent in gene t herapy, considerable caut ion should be exercised bef ore cont em plat ing it s applicat ion t o t rait s t hat do not have serious im plicat ions f or healt h. We not e t hat if som at ic gene t herapy f or t rait s in t he norm al range w ere t o becom e a possibilit y, any research w ould f all under t he rem it of t he GTAC.20 We recom m end, t heref ore, t hat t he GTAC and ot her relevant bodies should develop guidelines f or research int o gene t herapy f or norm al behavioural t rait s bef ore such research t akes place.

CH A PTER

13.30 M edical int ervent ions raise issues of saf et y because of t he pot ent ial side-eff ect s and adverse event s t hat may be relat ed t o t he use of a part icular drug. The regulat ory syst em f or licensing medicines and t he syst ems f or w arning individuals about pot ent ial risks w ill, of course, also apply t o new drugs developed as a result of research in behavioural genet ics. Nonet heless, it is import ant t o not e t hat adverse react ions t o drugs are one of t he leading causes of deat h in t he developed w orld. One serious concern is t hat , once medical int ervent ions are provided ‘over t he count er’, w it hout prescript ion, and perhaps f all out side t he st at ut ory regulat ions of medicinal product s, in t he w ay t hat some complement ary t herapies current ly do, t here may be risks of mis-selling and misleading market ing. We discuss t his f urt her in paragraphs 13.49 – 13.56 below.

13.32 Germline gene t herapy raises part icular issues concerning saf et y because t he eff ect s of t he t herapy reach f ar int o t he f ut ure and cannot be easily predict ed. The Clot hier Report concluded t hat ‘t here is insuff icient know ledge t o evaluat e t he risks [of germ line gene t herapy] t o f ut ure generat ions’ and t hat t heref ore ‘gene m odif icat ion of t he germ line should not yet be at t em pt ed’. In t he cont ext of behavioural variat ion w it hin t he norm al range, w hich by def init ion is not lif e-t hreat ening, w e cannot envisage any circum st ances in w hich t he m odif icat ion of t he hum an germ line w ould be just if iable.

18

Unit ed Nat ions Educat ional, Scient if ic and Cult ural Organisat ion. (November 1997). Universal Declarat ion on t he Human Genome and Human Right s.

19

Commit t ee on t he Et hics of Gene Therapy (Chairman: Clot hier, C.). (1992). Report of t he Commit t ee on t he Et hics of Gene Therapy. London: HM SO; Cm 1788.

20

GTAC’s remit is ‘t he deliberat e int roduct ion of genet ic mat erial int o human somat ic cells f or t herapeut ic, prophylact ic or diagnost ic purposes’. An analogous role is perf ormed in t he US by t he Food and Drug Administ rat ion (FDA). In July 2002, it w as report ed t hat t he FDA is t o creat e a new depart ment t o oversee gene t herapy, w it hin t he Cent er f or Biologics Evaluat ion and Research (New FDA Off ice f or Gene Therapy. (2002). Nat . M ed. 8, 646).

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(iii) Reversibility 13.33 An import ant quest ion concerning any int ervent ion is w het her or not it is reversible, since t here may be unw ant ed side eff ect s or ot her undesirable consequences, and because individuals aff ect ed by an int ervent ion may t hemselves change t heir minds about t he desirabilit y of it s eff ect s as social t rends and pract ical circumst ances change. Genet ic int ervent ions may be diff icult t o reverse, even w hen t hey are not t arget ed at st em cells, and as such, t heir use in t he cont ext of t rait s t hat are not regarded as diseases, and w hich might be inf luenced by ot her f orms of int ervent ion, ought t o be view ed w it h caut ion. The eff ect s of medical int ervent ions are of t en more easily reversible because t he eff ect of a drug w ill usually w ear off once it is no longer being ingest ed. The reversibilit y of environment al int ervent ions is dif f icult t o assess. It seems plausible t hat some int ervent ions t hat t ake place early in a person’s development may not be reversible in lat er lif e. The degree of reversibilit y of t he eff ect s of an int ervent ion w ill be part icularly import ant in considering w het her an int ervent ion is appropriat e f or a child, or someone unable t o give consent .

(iv) Choice 13.34 There are t hree w ays in w hich t he idea of individual choice is relevant here. The f irst , as w e have just not ed, is t hat individuals should be able t o exert t heir aut onomy w it h regard t o t he use of an int ervent ion. This has implicat ions f or t he use of int ervent ions in inf ancy and childhood, and f or int ervent ions t hat may be applied t o societ y at large, rat her t han t o an individual. On t he one hand, environment al int ervent ions of t en benef it all t he individuals in a part icular populat ion, w hereas medical int ervent ions w ould only benef it t hose ident if ied as requiring t he int ervent ion, and such t arget ed int ervent ions risk st igmat ising t he individuals receiving t hem. But , on t he ot her hand, it may be harder f or individuals t o avoid an environment al int ervent ion if t hey do not w ish t o make use of it . Examples of t his problem can be seen in t he debat es about f luoridat ion of t he w at er syst em or t he syst emat ic addit ion of f olic acid t o bread. 13.35 The second w ay in w hich t he not ion of choice is engaged is t he possibilit y t hat t here w ill be reduced t olerance f or diff erences and increased pressure t ow ards t he cult ivat ion or acquisit ion of t rait s t hat are perceived t o be desirable w it hin societ y. Familiar examples of t his t endency (not based on t he result s of genet ic research) include social pressures on individuals t o make use of cosmet ic surgery, cosmet ic ort hopaedics (t he use of ort hopaedic surgery t o lengt hen t he bones in t he legs), skin light ening and ot her processes t o make individuals more beaut if ul, t aller or Caucasian-looking. One can readily envisage similar pressure t o use genet ic t est s, w ere t hey t o become available, t o help design medical int ervent ions t o eliminat e ‘unat t ract ive’ personalit y t rait s. In t his w ay, individuals may f eel obliged t o make use of part icular int ervent ions. This seems a pot ent ial hazard in t he case of any t ype of int ervent ion. 13.36 The t hird aspect of choice t hat is import ant relat es t o t he eff ect of genet ic t est s on an individual’s self -percept ion. Genet ic t est s f or int elligence or sport ing abilit y might increase pressure on a person t o develop an aspect of t heir personalit y f or w hich t he t est is posit ive, or close off t he possibilit y of enjoying an act ivit y f or w hich t hey are led t o believe t hey are 'biologically unsuit ed'. In such cases, t he t est s could in f act only suggest malleable predisposit ions; but given t he likelihood of t heir misint erpret at ion by parent s as indicat ions of t heir children’s t alent s, any use of such t est s w ould need t o be very caref ully int roduced, cont rolled and monit ored. Indeed, even now, in t he case of disease or disorder, medical genet icist s are usually reluct ant t o t est children f or genet ic condit ions f or w hich t hey may 1 4 2

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A N D CH A N GI N G BEH AV I O U RA L TRA I TS

13.38 Similarly, in t he case of psychiat ric disorders, it is somet imes argued t hat t he use of medicines rat her t han ot her f orms of t herapy reinf orces t he t endency t o t hink of ourselves in mechanist ic t erms, undermining our concept ion of ourselves as responsible agent s. But t his case is much less convincing t han t hat envisaged above. Drugs do f orm an import ant and eff ect ive part of t he t reat ment of psychiat ric disorders, and if genet ic t est s indicat e a predisposit ion t o such disorders w hich might be prevent ed f rom having an eff ect by t aking suit able drugs, it is hard t o see w hat is w rong w it h such a course of act ion. There is lit t le merit in t he argument t hat a human lif e must involve suff ering or lack of f ulf ilment w here t his could be avert ed by some int ervent ion, only because t his int ervent ion is quicker or easier t han some alt ernat ive.

SELECTI N G

13.37 It has alw ays been acknow ledged t hat achievement is relat ed part ly t o f act ors out side an individual's cont rol, such as accident of genet ic endow ment , privilege of birt h and opport unit y. But t hese f act ors alone are not suff icient t o guarant ee success in most f ields. In order t o be a f irst -class at hlet e, or t o w in a f irst -class degree, t he individual has t o w ork hard, t o t rain t he body or brain, and t o mast er complex t echniques and memorise inf ormat ion, among ot her skills. One anxiet y concerning t he f ut ure is t hat genet ic and medical int ervent ions might subst ant ially replace t he eff ort of an individual in achieving such goals. At present , of course, t he possibilit y of such int ervent ions is t he st uff of science f ict ion and it is t heref ore diff icult t o assess and evaluat e t hese hypot het ical product s. But w hat one can say is t hat if almost anyone might be helped by t hese t echniques t o achieve w hat are now regarded as remarkable result s, t he t echniques w ould undermine t he signif icance of t hese result s as individual achievement s.22 As Parens has observed, ‘in many valued human act ivit ies, t he means of acquiring t he capacit ies required f or t he act ivit y are a part of t he very def init ion of t he act ivit y, and t ransf orming t hem t ransf orms, and can devalue, t he act ivit y it self .’ 23 This is one of t he concerns t hat underlies disapproval of t he use of drugs in sport .24 It is of course also possible t hat even great er achievement s might become possible t hrough a combinat ion of t hese int ervent ions and individual eff ort and skill. But commercial pressures t o exploit t hese possibilit ies w ould need t o be resist ed so t hat t he value of t hese achievement s could be judged caref ully in each case.

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(v) Intervention and individuality

CH A PTER

be pre-sympt omat ic and f or w hich no early int ervent ions exist .21 If t his is t he case w it h nonbehavioural or personalit y-relevant condit ions, t hen t here are even st ronger reasons f or caut ion w hen it comes t o int elligence and personalit y w here a diagnosis of predisposit ions might be misunderst ood by parent s or children t hemselves.

13.39 How does t his argument t ranslat e in t he case of behavioural t rait s in t he normal range? One might argue t hat it w ould not only be w rong t o inhibit people making use of such int ervent ions, but t hat t here are reasons t o encourage t heir use. It is not immediat ely obvious w hy it w ould be a bad t hing if people w ere generally less likely t o exhibit ant isocial

21

Clarke, A. The genet ic t est ing of children. In M art eau, T. M . & Richards, M ., edit ors. (1996). The Troubled Helix. Cambridge: Cambridge Universit y Press. The Nuff ield Council on Bioet hics has recommended in earlier publicat ions t hat predict ive genet ic t est ing of children in such circumst ances should not be permit t ed. (Nuff ield Council on Bioet hics (1993) Genet ic screening: et hical issues and (1998) Genet ics and ment al disorders: t he et hical cont ext ).

22

In addit ion, if everyone has t he capacit y t o achieve cert ain goals, t he advant age of at t aining t hose goals may be lost . If everyone becomes more int elligent , t hen one individual’s increased IQ score w ill not advant age him w it h respect t o ot hers.

23

Parens, E. (1998). Enhancing Human Traits: Ethical and Social Implications. Washington, DC: Georgetown University Press. p. 52.

24

See, f or example, Radick, G. Discovering and pat ent ing human genes. In Bainham, A., Day Sclat er, S. & Richards, M ., edit ors. (2002). Body Lore and Law s. Oxf ord: Hart . pp. 289–307.

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behaviour, or more likely t o be of high int elligence. As t hey get older, most people w ould w elcome a w ay of maint aining t heir ordinary capacit y f or memory.25 Assuming such t rait s could be enhanced in exist ing people w it hout undesirable side eff ect s or implicat ions f or genet ic diversit y, w ould it be w rong t o aim at such goals? It could be argued t hat a general increase in int elligence w ould not , in f act , increase happiness or provide social benef it s. But t his gloomy predict ion does not accord w it h our current social pract ices t hat aim t o provide more educat ion f or individuals, t o develop t heir cognit ive abilit ies and so f ort h. 13.40 One w ay t o t hink about t he dif f erence bet w een int ervent ions t arget ed at disorders, such as depression, and t hose int ervent ions speculat ively envisaged in t his sect ion, is t hat t he f ormer are primarily int ended t o help people overcome handicaps w hich prevent t hem f rom making t he most of t hemselves, w hereas t he speculat ive int ervent ions are supposed t o make it easy f or people t o achieve result s t hat are now only available t o a f ew especially t alent ed individuals. This dif f erence is a case of a general dist inct ion bet w een t herapy and enhancement ; and, just as in t he case of t he int ervent ions discussed here, t here is a w idespread view t hat w hereas t herapeut ic int ervent ions are generally valuable, t he possibilit y of enhancement is more problemat ic, giving rise t o, f or example, quest ions of f airness w here it is of limit ed availabilit y. So w e t urn now t o discuss t his dist inct ion and it s signif icance. Therapy versus enhancement 13.41 The w ay t o dist inguish bet w een t hose int ervent ions w hich count as ‘t herapies’ and t hose w hich count as ‘enhancement s’ is by ref erence t o t he condit ion t hat is t o be alt ered: t herapies aim t o t reat , cure or prevent diseases and t o alleviat e pat hological condit ions w hich place someone out side t he normal range, w hereas enhancement s aim t o improve already healt hy syst ems and t o advance capacit ies w hich already f all w it hin t he normal range. The dist inct ion bet w een healt h and disease is of course evaluat ive. Nonet heless, w e largely agree on w hat count s as a disease and on t he idea of an illness result ing f rom a f ailure t o f unct ion properly. So, most medical care is t herapy, concerned w it h t he prevent ion, t reat ment or cure of disease. By cont rast , f or example, cosmet ic surgery w hich simply aims t o alleviat e some of t he manif est eff ect s of ageing is enhancement .26 13.42 The dist inct ion bet w een t herapy and enhancement is of t en used t o just if y a dist inct ion bet w een int ervent ions w hich merit public support and t hose w hich do not . The suggest ion is t hat t here is a dut y t o ensure t hat our f ellow cit izens receive t herapies, but no dut y t o ensure t hat t hey receive enhancement s. In some respect s, t his principle needs qualif icat ion. Where resources are scarce, it may w ell be impossible t o provide eff ect ive public support f or t herapies; equally, as lat er discussion w ill show (paragraphs 13.44 – 13.48), t here may be enhancement s w hich are such t hat , if t hey are permissible at all, t hey should be available t o all. Nonet heless, t he principle w hich associat es t he dist inct ion bet w een t herapy and enhancement w it h t hat bet w een public and privat e provision is a usef ul st art ing-point in t his area.

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25

There is some evidence t hat t he ant i-Alzheimer drug Aricept can be used t o enhance memory, t hough it has disagreeable side-eff ect s. Yesavage, J. A. et al. (2002). Donepezil and f light simulat or perf ormance: eff ect s on ret ent ion of complex skills. Neurology 59, 123–5 (and see BBC New s. 8 July 2002. ‘Smart drugs’ boost pilot memory. ht t p://new s.bbc.co.uk/hi/english/healt h/new sid_2116000/2116476.st m. (9 August 2002)).

26

There is an ext ensive lit erat ure on t he def init ions of and diff erences bet w een healt h, disease, disorder and illness. An int erest ing analysis in t he area of psychiat ric disorders is provided in Fulf ord, K. W. M . (1989). M oral Theory and M edical Pract ice. Cambridge: Cambridge Universit y Press.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

A N D CH A N GI N G BEH AV I O U RA L TRA I TS

13.45 The anxiet y, how ever, is t hat if such t est s and int ervent ions w ere available f or privat e purchase, t he result could be t hat only t he more aff luent members of societ y w ould have access t o t hem. Because t hese t echniques w ould enhance capabilit ies, t his could lead t o even great er inequalit ies and increase social and economic polarisat ion. In part icular, w here not everyone has access t o t hese int ervent ions, equalit y of opport unit y is t hreat ened. One t heory about t he likely eff ect s of such polarisat ion w as post ulat ed by Lee Silver in his book Remaking Eden.27 In Silver’s f ut urist ic scenario, advances in diagnosis and reproduct ive t echnology enable t hose w ho can aff ord such services t o produce children w ho have great er skills and t alent s. He post ulat es t hat over t ime, societ y w ill segregat e int o t he ‘GenRich’ w ho cont rol t he economy, t he media, and t he know ledge indust ry, and t he ‘Nat urals,’ w ho w ork as low paid service providers or as labourers. (It may be observed t hat t his scenario is not dependent on genet ic enhancement ; arguably, it has alw ays happened, as a result of inequit able dist ribut ion of ot her inherit ed resources such as w ealt h, except in so f ar as t he modern st at e has int ervened t o promot e equalit y of opport unit y).28

SELECTI N G

13.44 Genet ic t est s and int ervent ions w hich lack any t herapeut ic applicat ion and are designed t o enable individuals t o enhance t heir capacit ies w it hin t he normal range provide t he cont ext f or t he issue raised in paragraph 13.42: w ho should be able t o make use of t est s and int ervent ions? And w ho should bear t he cost of t he t est s and int ervent ions? A st andard view is t hat since t he st at e does not have an obligat ion t o provide t echniques f or improving int elligence or at hlet icism, t hese int ervent ions should not normally be provided as part of a public healt hcare syst em. Nonet heless, it may also be argued, w it hin a f ree societ y and a f ree market , t hese t echniques should be available f or purchase.

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Access to interventions

CH A PTER

13.43 Alt hough t herapy is usually t hought of as t he t reat ment of diseases w it h an ident if iable biochemical basis, t here can be cases in w hich someone suff ers f rom a pat hological condit ion w hich places t hem out side t he normal range in some respect , w it hout t here being any such ident if ied basis f or it . In such cases, int ervent ions t o overcome t he result ing impairment are also t o be regarded as t herapies; hence t he basic principle aff irmed in t he previous paragraph implies t hat such int ervent ions merit public support t o make t hem available t o all. The import ant issue is t he severit y of t he handicap, not it s cause. We t ake t he view t hat t his conclusion should be applied t o int ervent ions w hich become available in t he f ield of behavioural genet ics. Any decision t o provide public support t hrough t he Nat ional Healt h Service (NHS) f or int ervent ions t o enable individuals t o overcome disabilit ies w hich obst ruct t heir capacit y f or behaviour in t he normal range should not be dependent on t he underlying cause of t he disabilit y.

13.46 The implicat ion of t hese considerat ions is t hat a societ y w hich values equalit y of opport unit y w ill ensure t hat genet ic t est s and int ervent ions t o enhance import ant behavioural t rait s, such as int elligence, should eit her be made f reely available t o all or limit ed t o special cases not dependent on privat e w ealt h. In bot h cases, as a hist ory of t he NHS in t he UK show s, it may w ell be t hat f inancial barriers t o access are not t he only ones; t here may be geographical, inst it ut ional and cult ural barriers t hat need t o be given act ive considerat ion. For w it hout some act ive engagement t o break dow n t hese barriers, it could

27

Silver, L. (1998) Remaking Eden. London: Weidenf eld.

28

M art in Richards has ident if ied ot her problems w it h Silver’s t heory. See Richards, M . Fut ure bodies: some hist ory and f ut ure prospect s f or human genet ic select ion. In Bainham, A., Day Sclat er, S. & Richards, M ., edit ors. (2002). Body Lore and Law s. Oxf ord: Hart . pp. 289–307.

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be t hat a societ y divides, not int o Silver’s ‘GenRich’ elit e and a ‘Nat ural’ majorit y, but int o a t alent ed majorit y and a ‘Nat ural’ (or ‘GenPoor’) minorit y underclass. 13.47 Public provision of new t est s and int ervent ions, especially w hen accompanied by f urt her eff ort s t o prevent t he f ormat ion of an underclass, w ould, of course, require considerable resources. For t he egalit arian, if t hese resources are not available, t hen t he t est s and int ervent ions should not be int roduced at all. But t here is a pow erf ul libert arian count erargument w hich draw s on t he exist ing pat t erns of invest ment in t he f ut ure of children by t hose w ho pay f or privat e schooling, t ennis coaching or French lessons. Libert arians argue t hat t here is no moral basis f or a dist inct ion bet w een int ervent ions based on genet ic variant s and t he f amiliar use of ext ra resources in t he f ields of educat ion and sport . In part icular, in t he cont ext of w hat might be t ermed ‘desirable’ t rait s such as increased int elligence, it is simply w rong t o ‘equalise dow nw ards’ by banning a part icular int ervent ion. If a t rait is desirable and t here is an int ervent ion t hat w ill increase t he likelihood of it occurring, t he correct response is t o ensure t hat it is available as w idely as possible. While t his may ent ail t hat , f or at least a limit ed period of t ime, t here w ill be some w ho do not have access, t he overall goal should be t o raise everyone t o t he highest level. As Ronald Dw orkin argues: ‘We should not … seek t o improve equalit y by levelling dow n, and, as in t he case of more ort hodox medicine, t echniques available f or a t ime only t o t he very rich of t en produce discoveries of more general value f or everyone. The remedy f or injust ice is redist ribut ion, not denial of benef it s t o some w it h no corresponding benef it s t o ot hers.’ 29 13.48 It is diff icult t o adjudicat e in t he abst ract bet w een t hese egalit arian and libert arian posit ions. It is only once some eff ect ive int ervent ion is under considerat ion t hat t he cost s and benef it s of f ull public availabilit y versus limit ed privat e availabilit y f or a privileged f ew can be assessed seriously. We believe t hat equalit y of opport unit y is a f undam ent al social value w hich is especially dam aged w here a societ y is divided int o groups t hat are likely t o perpet uat e inequalit ies across generat ions. We recom m end, t heref ore, t hat any genet ic int ervent ions t o enhance t rait s in t he norm al range should be evaluat ed w it h t his considerat ion in m ind.

M onitoring the provision of genetic tests and interventions 13.49 If genet ic t est s and corresponding genet ic, medical or environment al int ervent ions relevant t o t rait s in t he normal range are developed, it is import ant t o consider how such t est s and int ervent ions may be made available. Genet ic t est s f or variant s t hat inf luence behaviour in t he normal range might be t hought of as comparable t o personalit y or IQ t est s, rat her t han genet ic t est s t hat are used t o diagnose or predict t he onset of a serious disease such as cancer. Similarly, int ervent ions might be seen as comparable t o vit amin supplement s or cosmet ic surgery. In bot h cases, t heref ore, if t he comparisons are a guide, it may t urn out t hat individuals are lef t t o make decisions about w het her t o make use of t est s or int ervent ions w it hout t he involvement of healt h prof essionals.

29

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Dw orkin, R. (2000). Sovereign Virt ue: The Theory and Pract ice of Equalit y. Cambridge, M A: Harvard Universit y Press. p. 440.

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SELECTI N G A N D CH A N GI N G BEH AV I O U RA L TRA I TS

13.52 The ACGT w as subsumed in 2001 by t he Human Genet ics Commission (HGC), w hich current ly has responsibilit y f or administ ering t he code of pract ice. The HGC issued a public consult at ion document on t he supply of genet ic t est s direct t o t he public in July 2002.31 This summarises t he current sit uat ion and poses a number of specif ic quest ions covering issues such as consent t o t est ing, st orage and use of samples, and conf ident ialit y of dat a. It not es t hat t est s in t he f ield of behavioural genet ics are likely t o be part icularly cont roversial.

1 3

13.51 The remit of t his code of pract ice w as rest rict ed t o t est s f or genet ic disorders, and did not include t est s f or t rait s in t he normal range. Some of t he code’s requirement s are pert inent , including t he need f or verif iable ext ernal qualit y assurance and cont rol of laborat ories conduct ing t he t est s and t he import ance of prot ect ing t he conf ident ialit y of t he dat a obt ained. How ever, w e consider t hat t he issues raised by t est s f or behavioural t rait s and ot her t rait s t hat exhibit normal variat ion require specif ic at t ent ion. The quest ions addressed by t hese t est s include very sensit ive areas of personal and f amily vulnerabilit y, and t here is considerable pot ent ial f or exploit at ion of t he anxiet ies and aspirat ions of members of t he public in an area w here t he science is not w ell underst ood. This danger is part icularly import ant since bot h t est s and int ervent ions might be applied t o children w it hout t heir consent . Thus, w e t ake t he view t hat it is not adequat e in t his area t o rely on t he same mechanisms t hat apply t o non-genet ic or non-medical enhancement s, such as recourse t o t he Advert ising St andard Aut horit y or t he Off ice of Fair Trading, t o prevent misleading claims being made and ineff ect ive t est s f rom being sold.

CH A PTER

13.50 This has import ant implicat ions f or t he regulat ion and monit oring of t est s and int ervent ions. Wit hout appropriat e saf eguards, consumers may be at risk of exploit at ion t hrough misleading market ing pract ices. This is part icularly likely in novel areas of science, w here most people w ill not be w ell placed t o make inf ormed judgement s. In t he case of genet ic t est s, t here is current ly no specif ic legislat ion in place t hat w ould provide a regulat ory mechanism f or assessing t he eff icacy or reliabilit y of a t est . This applies even t o genet ic t est s f or diseases, as w ell as t o t he hypot het ical t est s f or genet ic inf luences on behavioural t rait s t hat are t he f ocus of t his Report . In 1997, t he Advisory Commit t ee on Genet ic Test ing (ACGT), a non-st at ut ory commit t ee t hat report ed t o t he Depart ment of Healt h, produced a Code of Pract ice and Guidance on Human Genet ic Test ing Services Supplied Direct t o t he Public.30 The code of pract ice w as a volunt ary one, and suppliers of genet ic t est s w ere expect ed t o submit t heir proposed t est s t o t he ACGT f or considerat ion bef ore int roducing t hem t o t he public. The ACGT not ed t hat it w ould be necessary t o review how successf ul t he volunt ary syst em proved t o be, and t o consider recommending ‘a more rigorous st at ut ory regime’ if necessary.

13.53 On t he presum pt ion t hat t est s f or genet ic inf luences on behavioural t rait s in t he norm al range, of varying qualit y and predict ive pow er, w ill becom e available, w e w elcom e t he considerat ion by t he HGC of genet ic t est s supplied direct ly t o t he public. We encourage t he HGC t o give t horough considerat ion t o t he issues raised by genet ic t est s f or behavioural and personalit y t rait s. We recom m end t hat bot h t he public and privat e provision of such t est s, if t hey are developed, should be st ringent ly m onit ored and regulat ed as necessary.

30

Advisory Commit t ee on Genet ic Test ing. (Sept ember 1997). Code of Pract ice and Guidance on Human Genet ic Test ing Services Supplied Direct t o t he Public. London: Healt h Depart ment s of t he Unit ed Kingdom.

31

Human Genet ics Commission. Consult at ion on Genet ic Test ing Services supplied Direct t o t he Public. ht t p://w w w.hgc.gov.uk/t est ingconsult at ion/index.ht m (16 Jul 2002).

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13.54 In addit ion t o genet ic t est s, int ervent ions may be developed, w het her medical, genet ic or environment al, on t he basis of inf ormat ion about genet ic variant s. The HGC consult at ion document recognises t hat some genet ic t est s may be accompanied by a corresponding int ervent ion t hat is recommended, depending on t he t est result s. How should such int ervent ions be regulat ed? It is usef ul here t o consider t he t ypes of int ervent ion separat ely. In t he case of genet ic int ervent ions, w e have already not ed (paragraph 13.31) t hat t he use of gene t herapy w ill be regulat ed by t he GTAC. 13.55 M edical int ervent ions such as pharmacological subst ances w ill not necessarily be classif ied as medicines. While some w ould be subject t o t he exist ing regulat ion in place f or medicines, ot hers might be classif ied as f oodst uff s or herbal remedies. Those w hich are not classif ied as medicines are unlikely t o be harmf ul, but t here is a risk t hat t hey w ill be promot ed on t he basis of unreliable, or even non-exist ent scient if ic evidence, and t hat consumers w ill be misled. Similarly, environment al int ervent ions, such as changes in lif est yle or surroundings, may be promot ed on t he basis of genet ic inf ormat ion about an individual. As not ed above, w e do not consider t hat t here are current ly any public bodies const it ut ed in such a w ay as t o monit or t he provision of such int ervent ions eff ect ively and ensure t hat t hey are appropriat e and of suff icient ly high qualit y. We recom m end, t heref ore, t hat t hose charged w it h t he m onit oring and regulat ion of genet ic t est s f or behavioural t rait s in t he norm al range should also be responsible f or ensuring appropriat e m onit oring of t he provision of int ervent ions based on such genet ic inf orm at ion, w hich f all out side t he scope of ot her regulat ory bodies. 13.56 We not e t he diff icult ies f or monit oring and regulat ion raised by t he sale of exist ing t est s and int ervent ions on t he int ernet , and encourage t he eff ort s of t he Off ice of Fair Trading and consumer prot ect ion agencies such as t he Nat ional Consumer Council and t he Consumers’ Associat ion in developing codes of pract ice and st rat egies, such as kit e-marks f or assist ing consumers.

Prenatal selection

Technologies for prenatal testing and selection 13.57 The speculat ive int ervent ions discussed so f ar are generally applied t o t hose already born (alt hough many environment al and medical int ervent ions can aff ect f et uses, and it is possible t hat gene t herapy could be carried out in ut ero). In t he last sect ion of t his chapt er w e consider a diff erent t ype of int ervent ion t hat aff ect s t he t rait s of an individual, not by alt ering t hem but by select ing t hem in advance. One such int ervent ion is prenat al t est ing, w hich has been pract ised on clinical grounds f or t hirt y years in t he UK. Techniques such as serum screening, ult rasound scanning and amniocent esis are in w idespread use t o det ect pregnancies aff ect ed by Dow n’s syndrome, spina bif ida or ot her abnormalit ies, in order t o off er couples early inf ormat ion on t he pregnancy. M any couples opt f or t erminat ion of pregnancy if abnormalit ies are det ect ed. These t echniques are know n as prenat al diagnosis (PND). 13.58 A second int ervent ion has been developed over t he last 15–20 years, in w hich t he process of in vit ro f ert ilisat ion (IVF) has been coupled w it h embryo biopsy. Fert ilisat ion of eggs by sperm t akes place in t he laborat ory. Embryos are allow ed t o grow t o t he eight -cell st age, at w hich point one or t w o cells are removed f or genet ic t est ing. The remaining cells of t he embryo st ill have t he pot ent ial f or normal development . Having t est ed each embryo, doct ors can off er prospect ive parent s t he choice of w hich embryo is reint roduced. This t echnique is know n as pre-implant at ion genet ic diagnosis (PGD). In t he UK, st ringent 1 4 8

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

PND, w hich can lead t o t he select ive t erminat ion of pregnancy, can be dist inguished f rom PGD, w hich involves t he select ive implant at ion of embryos. Because abort ion is an invasive procedure of t en associat ed w it h dist ress, it might be suggest ed t hat PND on non-clinical grounds is less likely t o become w idespread t han t he less t raumat ic process of PGD.

34

It is possible t o t ake select ion back yet anot her st age: t here is a phenomenon import ant in research in genet ics called ‘assort at ive mat ing’, w hich ref ers t o t he f act t hat people of t en choose part ners w ho have similar t rait s (see paragraph 9.12). For example, t here is a posit ive correlat ion as high as 0.47 bet w een husbands and w ives on IQ scores (eg. DeFries, J. C. et al. (1979). Familial resemblance f or specif ic cognit ive abilit ies. Behav. Genet . 9, 23–43), t hough correlat ions f or ot her personalit y t rait s are much low er. What ever t he precise correlat ions, t he f act remains t hat people do choose w ho t o have children w it h, and t hese decisions may in part be based on charact erist ics such as appearance, int elligence and personalit y. Thus, t he philosopher John Harris has argued t hat all decisions t o have a child involve select ion: nat ural concept ion is not a random exercise.

TRA I TS

33

BEH AV I O U RA L

Recent ly, t his w as ext ended t o allow t he parent s of a child w it h a serious blood disease t o select an embryo t hat did not have t he same condit ion and w hich had been t issue-t yped t o ensure t hat it could be a mat ched donor of bone marrow cells t o it s sibling. The HFEA announced on 13 December 2001 t hat PGD and embryo select ion w ould be allow ed in order t o ensure t he birt h of a child w it hout a genet ic disorder w ho w ould be a mat ched donor f or a sibling. The w ay in w hich t his decision w as reached w as crit icised by t he House of Commons Select Commit t ee on Science and Technology. (House of Commons Science and Technology Commit t ee. (18 July 2002). Development s in Human Genet ics and Embryology. Fourt h Report of Session 2001–02. London: HM SO). The HFEA subsequent ly reject ed an apparent ly similar request f rom a f amily w hose child suff ered f rom a rare condit ion called Diamond Blackf an anaemia. Their applicat ion w as t urned dow n on t he grounds t hat t he embryos w ere at no increased risk of having t he condit ion: t he use of PGD and t issue t yping w ould be purely f or t he benef it of t he exist ing child, and w as not necessary t o ensure t he healt h of t he implant ed embryo. This ruling cont radict ed t he advice of t he HFEA’s ow n Et hics Commit t ee w hich t ook t he view t hat t here w as no moral dist inct ion bet w een t he t w o t ypes of case (Et hics Commit t ee of t he HFEA. (November 2001). Et hical Issues in t he Creat ion and Select ion of Preimplant at ion Embryos t o Produce Tissue Donors).

CH A N GI N G

32

A N D

‘Designer baby’ is one of t hose t erms, like ‘Frankenst ein f oods’ and ‘slippery slope’, w hich is cent ral t o public discourse on genet ics, but w hich can be misleading. The w ord ‘design’ can connot e a purpose, a plan or t he idea of f ashion design. The use of t he phrase ‘designer babies’ in t he media and public debat e conf uses t hese t hree aspect s of t he t erm. Underst ood in t he t hird sense list ed, t hat of f ashion, t he phrase ‘designer baby’ could ref er t o a general process in w hich babies are valued f or w hat might be t hought t rivial reasons, such as hair or eye colour. This w ould be a ‘designer baby’ in t he sense t hat it exemplif ies t he values of a

SELECTI N G

Box 13.2: ‘Designer babies’

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13.59 Anot her, largely t heoret ical, approach w ould move select ion f urt her back in t ime, by allow ing choice bet w een diff erent gamet es. Experiment al t echniques now allow sperm t o be sort ed, enabling parent s t o choose t he sex of t heir embryo. This t echnique remains somew hat unreliable: t here are report s of an 8% error rat e f or f emales and 28% in males. It is not clear t hat t his t ype of t echnique w ill ever be applicable t o t rait s ot her t han sex, and it is part icularly diff icult t o envisage it s applicat ions t o t he complex t rait s considered in t his Report .34 The use of PGD and sperm sort ing are just t w o t echnologies t hat have generat ed concerns about so-called ‘designer babies’ (see Box 13.2).

CH A PTER

regulat ion of t his t echnology by t he Human Fert ilisat ion and Embryology Aut horit y (HFEA) means t hat it is only current ly off ered t o f amilies aff ect ed by inherit ed disorders such as Duchenne’s muscular dyst rophy and cyst ic f ibrosis.32 PGD means t hat parent s can ensure t hat t heir child does not have t hese serious diseases, but avoid t he t erminat ion of pregnancy, a process w hich is emot ionally or morally unaccept able t o many people.33 The benef it s of PGD over PND are t hat t he out come is a healt hy pregnancy, rat her t han t erminat ion of an est ablished pregnancy accompanied by t he need t o st art again at concept ion. The disadvant age is t hat IVF is an int rusive procedure, w hich may have t o be carried out on numerous occasions bef ore a successf ul pregnancy is achieved. There are, how ever, diff icult ies in obt aining f unds f rom healt h aut horit ies f or IVF, so in pract ice it is provided largely by t he privat e sect or in t he UK.

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consumer societ y and an unhealt hy f ocus on unimport ant , f rivolous charact erist ics. An alt ernat ive use of t he t erm ‘designer baby’ has been t o ref er t o a child w hose charact erist ics have been deliberat ely chosen, rat her t han lef t t o chance, such as t he recent cases of embryos being select ed in such a w ay t hat t heir cord cells can be used t o provide donor cells f or a sibling.* This use of t he t erm misleadingly implies t hat part icular charact erist ics of a child are being manipulat ed or engineered. In realit y, t he only t echniques current ly available are t he select ion of gamet es bef ore f ert ilisat ion, of embryos bef ore implant at ion or select ive t erminat ion of pregnancy. These t echniques are all examples of t he select ion or choice of alt ernat ive opt ions rat her t han t he act ual manipulat ion or design of babies. There is a t hird pot ent ial use of t he phrase ‘designer baby’, w hich ref ers t o t he possibilit y of t ruly designing a child, by choosing charact erist ics f rom a menu of possibilit ies t o creat e a child, f or example using gene t herapy, but t his not ion is st ill in t he realms of science f ict ion.

*

For example: The Sun (11 April 2002). A designer baby w ould end our heart ache; Guardian (23 February 2002). Designer baby get s t he go ahead; The Times (25 February 2002). Brit ish couples queue up t o have ‘designer’ babies; Independent (24 February 2002). Five more designer babies on w ay in UK.

13.60 Bef ore discussing t he et hical argument s surrounding use of prenat al select ion by PND or PGD, it is import ant t o emphasise point s made earlier regarding t he pract ical diff icult y of select ing f or behavioural t rait s using t hese t echnologies. Because of t he mult iplicit y of genes involved, a very large number of embryos w ould need t o be screened bef ore t he desired ‘chance’ combinat ion of genes w as obt ained. Indeed, given t hat t he available genes w ill depend on t he genot ype of t he parent s, it may not be possible t o f ind t he ‘ideal’ combinat ion. Current ly, IVF t ends t o produce, on average, only about f our t o f ive embryos f or each couple undergoing t reat ment .

Selection on non-clinical grounds: ethical arguments 13.61 The f orms of select ion out lined above are current ly only pract ised on clinical grounds in t he UK. How ever, t he st art of a t rend t ow ards select ion on ot her grounds can be ident if ied. The recent decision by t he HFEA t o allow t he select ion of embryos f ree f rom genet ic condit ions t hat can also act as donors t o exist ing siblings is an import ant move in t his direct ion.35 Anot her relevant example is sex select ion. In t he UK, PND and PGD can be used f or sex select ion if it is necessary f or clinical reasons, f or example t o avoid t he birt h of a child w it h an X-linked genet ic disease. How ever, t here is a policy of not off ering sex select ion on nonclinical grounds using PGD or PND. In t he US, t he Et hics Commit t ee of t he American Societ y of Reproduct ive M edicine concluded t hat PGD should not be init iat ed f or purposes of sex select ion, and t hat PGD f or sex select ion during IVF t reat ment should not be encouraged.36 A complex set of concerns underlies such policies, involving t he et hics of t erminat ing healt hy pregnancies, t he need t o accept off spring f or t hemselves and not t heir part icular charact erist ics, t endencies in some societ ies t o f avour male rat her t han f emale off spring, and t he limit ed availabilit y of genet ic services.

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35

See f oot not e 32 above.

36

Et hics Commit t ee of t he American Societ y of Reproduct ive M edicine. (1999). Sex select ion and preimplant at ion genet ic diagnosis. Fert ilit y and St erilit y 72, 595–8.

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13.64 In t he US, most companies also provide inf ormat ion about t he educat ional qualif icat ions of donors and even t heir grades on school and college examinat ions. Some individuals w ho regard t hemselves as ‘high achievers’ have subsequent ly sold or given aw ay t heir sperm on t he int ernet . The most f amous sperm bank of t his kind w as t he Reposit ory f or Germinal Choice, w hich operat ed f rom 1980 t o 1999. It collect ed sperm f rom people of high int elligence, including a number of w inners of t he Nobel Prize and t he Field medal, a prest igious aw ard in mat hemat ics. M en of high int elligence w ho had f amily hist ories of serious genet ic disease or disorders such as schizophrenia w ere excluded. Women purchasing t he sperm w ere excluded if t hey w ere unmarried, unhealt hy, over t he age of 40 or had criminal records. Anot her group t hat received considerable publicit y is Ron’s Angels, w hich off ers donor eggs and sperm f rom at t ract ive men and w omen. The company’s w ebsit e asks, ‘If you could increase t he chance of reproducing beaut if ul children and t hus giving t hem an advant age in societ y, w ould you?’ 40

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13.63 There are numerous companies in t he US t hat off er inf ert ile couples t he opport unit y t o purchase donor sperm or eggs. Donors w it h a f ew common genet ic or inf ect ious diseases are excluded, alt hough some genet ic risk remains nevert heless. Some inf ormat ion about various charact erist ics of donors is made available t o prospect ive parent s, including eye, hair and skin colour, so t hat parent s can aim t o have children w ho bear some physical resemblance t o t hem. In t he UK, couples requiring donat ed sperm are able t o make use of similar inf ormat ion t o provide a means of mat ching t he charact erist ics of t he donor t o t hat of t he husband. How ever, it has been suggest ed t hat privat e f ert ilit y clinics in t he UK may allow couples t o ‘select sperm donors w ho bear lit t le resemblance t o t hemselves’, in part icular, donors w ho have ‘desirable’ charact erist ics.38 The 5t h Code of Pract ice of t he HFEA does not explicit ly st at e t hat parent s may not select ‘desirable’ t rait s w hen choosing a gamet e donor.39 It only st at es, in sect ion 3.18, t hat ‘cent res should t ake int o account each prospect ive parent ’s pref erences in relat ion t o t he general physical charact erist ics of t he person providing gamet es f or donat ion.’ Prevent ing t he select ion of gamet es based on non-clinical f eat ures, w het her physical charact erist ics or behavioural t rait s such as int elligence or personalit y w ould t heref ore require new guidance.

CH A PTER

13.62 Recent ly, some comment at ors in t he US have called f or t his policy t o be reassessed and f or t he possibilit y of sex select ion of gamet es t o be reconsidered in cert ain circumst ances.37 In t he UK, t he Government has request ed t hat t he HFEA examines t he advances in t echniques of gamet e select ion on t he basis of sex, somet hing w hich is already possible and unregulat ed in t he privat e sect or. The HFEA int ends t o launch a public consult at ion on sex select ion in lat e 2002.

13.65 Law and clinical pract ice support t he use of genet ic inf ormat ion t o provide inf ormed choice f or prospect ive parent s. But prof essional and public opposit ion has been voiced, f or a variet y of reasons, t o t he use of non-clinical at t ribut es such as t he t rait s considered in t his Report in t est ing and select ion. There seems t o be a consensus in clinical genet ics and in public opinion against use of PGD or PND in order t o select babies on t he basis of non-

37

Robert son, J. A. (2001) Preconcept ion gender select ion, Am. J. Bioet hics 1, 2–9.

38

Calvert , J. & O’Reilly, J. (2002). Babies-t o-order raise ‘eugenic’ f ears. The Sunday Times. 21 July.

39

Human Fert ilisat ion and Embryology Aut horit y. (2001). Code of Pract ice. 5t h Edit ion.

40

Ron’s Angels. Egg Auct ion. 2000. ht t p://w w w.ronsangels.com/auct ion.ht ml (16 Jul 2002). The w ebsit e st at es t hat t he company has generat ed an income of $3.2 million in sales since 1999.

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Box 13.3: View s about prenatal selection expressed by respondents to the public consultation ‘We have grave concerns regarding prenat al t est ing f or any t rait ot her t han in unt reat able genet ic disorders t hat normally result in deat h.’ Royal College of Psychiat rist s ‘We need a w ide variet y of behaviours, personalit ies and t emperament s if human societ y is t o adapt t o t he changing circumst ances w e f ind ourselves in. Variet y is t he spice of lif e, and it is also essent ial f or evolut ion.’ Grant Vallance, PhD st udent , Open Universit y ‘in an increasingly aut onomy-orient ed climat e, it may be impossible t o draw f irm lines against such select ion … Use of law t o prevent such select ion is t he w orst possible alt ernat ive, because it opens t he door t o ot her rest rict ions on people’s decisions about reproduct ion.’ Prof essor Dorot hy C Wert z, Universit y of M assachuset t s

clinical charact erist ics (Box 13.3 cont ains examples of responses t o t he Working Part y’s public consult at ion t hat address t his issue). In t he case of PND, w e share t his view . Set t ing aside t he cont est ed issue of t he et hics of abort ion on social grounds, w hich is out side t he scope of t his Report , w e t ake t he view t hat t he use of select ive t erm inat ion f ollow ing PND t o abort a f et us m erely on t he basis of inf orm at ion about behavioural t rait s in t he norm al range is m orally unaccept able. 13.66 But t he issues raised by t he use of PGD are diff erent . Whereas select ive t erminat ion f ollow ing PND is applied t o a f et us t hat has already implant ed and is developing in t he w omb, PGD is used t o select w hich embryos t o implant . Thus, PGD does not precede t he t erminat ion of a pot ent ial human lif e, but precedes inst ead t he choice as t o w hich embryo, among t hose creat ed by IVF, is t o be given a chance of developing int o a human being. And in t his cont ext , it is not so clear t hat it is morally unaccept able t o make t his choice on t he basis of genet ic inf ormat ion about t he t rait s t hat are t he f ocus of t his Report . Whereas PND w ould be used t o end a lif e, PGD is, in eff ect , used t o choose w hich lif e t o st art . Hence, t he moral prohibit ions w hich apply in t he case of PND, do not apply in t he same w ay in t he use of PGD. Nonet heless, t he pot ent ial use of PGD t o select embryos t hat are more or less likely t o exhibit part icular behavioural t rait s is w idely t hought unaccept able. In t he f inal part of t his chapt er, w e at t empt t o evaluat e t his posit ion.

For selection (i) The right t o proceat ive aut onomy 13.67 The main argument in f avour of t he permissibilit y of select ion is t hat t his is a legit imat e exercise of individual libert y. There is, quit e generally, a st rong presumpt ion in f avour of t he exercise of individual libert y w herever it s exercise does not conf lict , direct ly or indirect ly, w it h t he legit imat e int erest s of ot hers. This presumpt ion is especially pow erf ul w hen t he act ivit y in quest ion lies w it hin w hat is normally t he sphere of privat e lif e, as t he concept ion of children clearly does. For, on t he one hand, w it hin t his sphere it is hard t o see how ot hers are harmed by w hat is done; and, on t he ot her hand, int imat e mat t ers of

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CH A PTER

t his kind mat t er great ly t o t hose direct ly concerned, so t hat it is all t he more import ant and diff icult t o just if y any int erf erence in t hem. Hence, t he liberal posit ion is somet imes described in t erms of t he exist ence of a ‘right t o procreat ive aut onomy’, w hich w ould include a right t o employ saf e and reliable met hods f or t he select ion of children w it h a genet ic predisposit ion f or enhanced abilit ies w it hin t he normal range.41

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This concern can be seen as arising f rom t he eugenic programmes w e discussed in Chapt er 2, in w hich people w it hout desirable t rait s w ere devalued and abused.

TRA I TS

Dw orkin, R. (1993). Lif e’s Dominion. London: Harper Collins.

42

BEH AV I O U RA L

41

CH A N GI N G

(ii) Equalit y 13.69 We have not ed previously (paragraphs 13.44 – 13.48) t hat t he int roduct ion of int ervent ions based on genet ic t est s w hich aim t o enhance abilit ies w it hin t he normal range poses a t hreat t o t he equalit y of opport unit y. Does t he same anxiet y apply here? Since prenat al select ion is t he issue, it is not clear t hat it does: f or a child w ho is conceived and born w it hout any met hod of select ion is not someone w ho has been deprived of an opport unit y f or enhancement t hat has been made available t o a child w hose concept ion has made use of met hods of select ion such as PGD. In t his cont ext , t he met hod involved is one t hat select s f or diff erent people, rat her t han enhancing t he abilit ies of a given person. Nonet heless, egalit arian anxiet ies do have a genuine basis: a societ y divided bet w een t hose possessing enhanced abilit ies as a result of prenat al select ion and t hose conceived nat urally w it h t he ordinary range of abilit ies might w ell develop consequent ial divisions w hich make lif e more diff icult f or ordinary people. But much depends here on t he rest of t he assumed social and polit ical cont ext . If w e assume a democrat ic cont ext w hose polit ical inst it ut ions and cult ure are organised in such a w ay t hat t he public as a w hole, and in part icular t hose w ho are less t alent ed, benef it f rom t he except ional abilit ies of a f ew, especially t alent ed individuals, t hen t here seems no good reason f or t hinking t hat t hings w ill get w orse, in w ays t hat are unf air, if such people are creat ed. By cont rast , if t he societ y is one in w hich a t alent ed elit e enjoy t heir good f ort une w it hout any commensurat e benef it s f or t he rest of societ y, t hen

A N D

(i) The ‘expressivist ’ argument 13.68 One argument opposes select ion f or t rait s in t he normal range because of t he signals it might send about t he value of diff erent t ypes of people and diff erent f orms of lif e. M any advocat es of disabilit y right s use t his ‘expressivist ’ object ion t o oppose select ion on clinical grounds, arguing t hat t erminat ion of pregnancies aff ect ed by disabilit y signals t hat disabilit y is unaccept able or t hat disabled people are inf erior.42 In t he case of behavioural genet ics, if parent s used select ion t o avoid t he birt h of babies carrying alleles associat ed w it h homosexualit y, f or example, t his might ref lect and reinf orce prejudices such as homophobia. Select ion f or higher int elligence or sport ing prow ess might be t hought t o similarly devalue ot hers w ho did not possess t hese t rait s, or w hose parent s could not aff ord t o invest in select ion t echniques. How ever, t his argument does not seem part icularly st rong in t he case of non-disease t rait s. By def init ion, most of t he t rait s in quest ion are possessed in some degree by everyone and many of t hem, such as higher int elligence, are already valued w idely in societ y and aimed at t hrough educat ional programmes and ot her social policies. So it is hard t o see w hy permit t ing select ion on t he basis of genet ic predisposit ions in f avour of enhanced abilit ies w it hin t he normal range, if it w ere possible, should be t hought t o ‘express’ a specially w orrying evaluat ion of t hese abilit ies w hich is not already manif est in social pract ices.

SELECTI N G

Against selection

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t here is no reason w hy t he lat t er should w elcome t he creat ion of a larger and correspondingly more pow erf ul elit e. 13.70 The conclusion t o be draw n, t heref ore, is t hat t he int roduct ion of PGD as a met hod of prenat al select ion does provide grounds f or egalit arian anxiet ies; but also t hat if one assumes a background social and polit ical syst em in w hich ant i-elit ist egalit arian values are already w ell ent renched, it should be possible t o accommodat e prenat al select ion w it hout any great result ing unf airness. Hence, t he judgement in any part icular case as t o w het her t here is a signif icant egalit arian object ion t o prenat al select ion depends on w het her egalit arian values are already w ell est ablished in t he social and polit ical cont ext in quest ion. (iii) Nat ural humilit y 13.71 The int uit ive object ion t o prenat al select ion is t hat it is ‘int erf ering w it h nat ure’. By it self t his is no argument , since all medical int ervent ions involve some such int erf erence. But t he ‘conservat ive’ opponent of prenat al select ion w ill argue t hat t he kind of int erf erence involved in prenat al select ion undermines t he proper relat ionship bet w een parent s and t heir children. For by invit ing parent s t o exercise t heir pref erences in making a select ion it int roduces an element of cont rol over t he result of concept ion w hich makes t he experience of parent hood very diff erent f rom t he present sit uat ion in w hich, in t he majorit y of cases, parent s are happy just t o t ake t heir children as t hey f ind t hem. One might compare t he present sit uat ion t o t hat of eat ing at t he kind of f amily rest aurant w hich used t o be common, w here t here is no menu and one simply t akes w hat is given; and t hen compare t he envisaged use of prenat al select ion t o eat ing at a rest aurant w here t here is a menu f rom w hich one can make a select ion (and send back a dish if it w as not w hat one ordered). Just t o make t his comparison, of course, is not t o provide an argument ; and t he challenge f or conservat ive opponent s of prenat al select ion is t o convert t his kind of int uit ive react ion against prenat al select ion int o argument s t hat are robust enough t o def eat t he liberal proponent s of a ‘right t o procreat ive aut onomy’ (see paragraph 13.67 above). 13.72 One at t empt t o do so has been made by Deena Davis, w ho deploys Joel Feinberg’s argument t hat children have a right t o an open f ut ure.43 This concept w as developed by Feinberg in relat ion t o exist ing children, t o explain t hat t hey had right s w hich t hey w ere not capable of exercising but w hich should be ‘held in t rust ’ f or t hem unt il t hey w ere f ully aut onomous individuals. Unt il t hat point , anyt hing t hat reduced t he child’s available opt ions and eliminat ed opport unit ies f or it t o make it s ow n choices could be said t o inf ringe it s right t o an open f ut ure. If t his argument is t ransf erred t o prenat al select ion, it might suggest t hat choosing t rait s – f rom sex t o enhanced abilit ies – narrow s t he opt ions f or t hat child. The obvious diff icult y w it h t his argument , how ever, is t hat it mischaract erises t he parent al choice: f or it is a choice bet w een diff erent possible children and not one concerning diff erent abilit ies w hich one and t he same child might have possessed. So it is not t rue in a st raight f orw ard sense t hat prenat al select ion ‘narrow s t he opt ions’ f or a child. 13.73 Nonet heless, it can be argued t hat w hat is w rong w it h prenat al select ion is t hat it rest rict s a child’s f reedom by t he pressure it places upon a child t o f ulf il t he hopes and w ishes of t he parent s w hich guided t heir decision t o select t hat child f or implant at ion rat her t han t he ot her embryos t hat w ere available. People w ho w ant a male child so st rongly t hat t hey resort t o prenat al select ion t echniques may w ell seek t o bring up t heir

43

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Davis, D. S. (2001). Genet ic Dilemmas. New York: Rout ledge.

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A N D CH A N GI N G BEH AV I O U RA L TRA I TS

13.76 For t he conservat ive, parent al love w hich includes t his element of nat ural humilit y is, t heref ore, incompat ible w it h t he w ill t o cont rol. It is not compat ible w it h at t empt s t o int erf ere in t he lif e of a child except w here t he int erf erence is in t he child’s ow n int erest . Equally, it is not compat ible w it h t he pract ice of prenat al select ion w hich seeks t o ident if y, as a basis f or choice, genet ic predisposit ions f or enhanced abilit ies or special t rait s. For t his is an at t empt t o det ermine t he kind of child one w ill have, w hich is precisely not t he uncondit ional, loving accept ance of w hat ever child one t urns out t o have.

SELECTI N G

13.75 Nat ural humilit y is ent irely compat ible w it h t he f amiliar parent al aspirat ion, w hich is indeed anot her element of parent al love, t hat one should do w hat one can t o enable one’s children t o make t he best of t hemselves by overcoming nat ural w eaknesses and developing nat ural abilit ies by means of educat ion, encouragement and so on. Involvement s of t his kind, how ever, are not at t empt s t o ensure a specif ic f ut ure f or a child. Not only are such at t empt s likely t o f ail, t hereby leading t o resent ment or a sense of f ailure or bot h; more import ant ly, t hey manif est a f ailure by parent s t o underst and t hat parent al love requires t he respect w hich gives children t he opport unit y t o f rame t heir lives f or t hemselves in accordance w it h t heir ow n abilit ies and aspirat ions.

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13.74 The conservat ive opponent of prenat al select ion holds t hat t his kind of parent al pressure is a sympt om of t he changed relat ionship bet w een parent s and children w hich prenat al select ion w ill mot ivat e. At present , parent s accept t heir children as t hey f ind t hem in an at t it ude of ‘nat ural humilit y’ t o t he unchosen, or chance result s of procreat ion. This at t it ude is an import ant f eat ure of parent al love, t he love t hat parent s ow e t o t heir children as individuals in t heir ow n right ; f or t his is a love t hat does not have t o be earned and is not dependent on a child having charact erist ics t hat t he parent s hoped f or. When w e f all in love as adult s w e exercise some degree of choice in select ing our part ner, t he person w e love. But parent al love f or children does not include a similar element of choice and it w ould be very dest ruct ive of it if it w ere t o do so.

CH A PTER

son t o conf orm t o a st ereot yped gender role. It can be object ed t hat one should dist inguish t he select ion of an embryo f rom w hat parent s do t o t he result ing child once he or she exist s. There is no reason t o assume t hat parent s, having select ed a child, w ould necessarily place pressure on t he child or t reat him or her in an undesirable w ay. How ever, if people care so st rongly about a t rait t hat t hey are w illing t o select f or it , it is perhaps t o be expect ed t hat t hey w ill rear t he child in a st ereot ypical w ay or place pressure on t he child and be upset if he or she does not f ulf il t he aspirat ions f or w hich t hey have select ed.

13.77 For t he conservat ive, t heref ore, t he advocat es of prenat al select ion in t he name of t he right t o procreat ive aut onomy f ail t o t ake account of t he value inherent in our present at t it ude of nat ural humilit y, w hich inf orms t he loving relat ionship bet w een parent s and children. They urge t hat in t his most int imat e area of personal lif e w e should seek t o curb our w ill t o cont rol. 13.78 Given t hat w e are dealing here w it h only speculat ive possibilit ies, and since t he likely small eff ect s of individual genes may make accurat e predict ions of f ut ure behaviour very diff icult , it is hard t o evaluat e t he disagreement bet w een t he conservat ives and t he liberals. In part icular, it may be t hat t he cont rast bet w een t he liberal’s aff irmat ion of a right t o procreat ive aut onomy and t he conservat ive’s def ence of nat ural humilit y is t oo simple. It might t urn out t hat t here are possibilit ies f or modest applicat ions of PGD in relat ion t o t he

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t rait s considered in t his Report w hich w ould not seriously undermine t he present relat ionship bet w een parent s and t heir children. While not ent irely persuaded by t his conservat ive line of argum ent , w e do accept t hat , at present , t he case f or perm it t ing prenat al select ion based on t he ident if icat ion of genet ic predisposit ions f or enhanced abilit ies rem ains t o be m ade. We recom m end, t heref ore, t hat t he t echnique of preim plant at ion genet ic diagnosis, w hich is current ly rest rict ed t o serious diseases and disorders, should not be ext ended t o include behavioural t rait s in t he norm al range such as int elligence, sexual orient at ion and personalit y t rait s.

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Chapter Legal responsibilit y

14

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

RESPO N SI BI LI TY

14.2 Int erest in biological explanat ions of criminal behaviour is by no means new. In t he ninet eent h cent ury t he It alian criminologist , Cesare Lombroso, w rot e ext ensively on t he associat ion bet w een crime and physiognomy, draw ing at t ent ion t o w hat he saw as t he t ypical f acial and cranial f eat ures of t he criminal.1 Int erest in Lombrosan criminology w aned, but t his movement expressed a w idespread and persist ent ent husiasm f or ident if ying a physical explanat ion of crime. It is t his same int erest w hich prompt ed research in t he mid-t w ent iet h cent ury int o t he dist ribut ion of body t ypes amongst juvenile off enders, and, arguably, w hich prompt s cont emporary int erest in scient if ic explanat ions of ant isocial behaviour, w het her t he pref erred t heory be neurological, diet ary or genet ic. Alt hough such int erest is underst andable, it is import ant t hat a desire f or a simple, int elligible cause of a serious social problem should not obscure t he need f or scient if ic rigour in scrut inising t he claims of such t heories. Crime is a complex phenomenon, and int erpret at ions of crime t hat f ocus on one aet iological f act or are likely t o be misleading. Such approaches are also open t o t he crit icism t hat t hey represent t he ‘quick f ix’ response, t hereby obscuring t he need t o address ot her, pot ent ially more expensive and uncomf ort able solut ions.

LEGA L

The history of biological explanations of human behaviour in law

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14.1 We concluded in Chapt er 12 t hat t he result s of research in behavioural genet ics do not w arrant a subst ant ial revision of our current concept ions of human act ion and moral responsibilit y. How ever, one area in w hich t he research may have more immediat e and more persuasive implicat ions is in t he at t ribut ion of legal responsibilit y and t he role of punishment . In t his chapt er, w e consider t he st at us of biological explanat ions of behaviour in t he cont ext of criminal law and t he possible impact of behavioural genet ics on t he legal syst em. In t he f ollow ing chapt er w e consider issues t hat also concern t he law, namely employment and insurance, but t his chapt er f ocuses on criminal law and responsibilit y f or criminal behaviour.

CH A PTER

Legal responsibilit y

14.3 Some comment at ors have suggest ed t hat t he search f or genes t hat inf luence crime or ant isocial behaviour is f undament ally misconceived, since crime is a socially const ruct ed phenomenon. This crit icism has also been levelled at research in behavioural genet ics int o ot her t rait s, including int elligence and personalit y charact erist ics, but it is part icularly pert inent in t he case of crime and ant isocial behaviour. Nikolas Rose has not ed t hat biological criminologist s are: ‘quick t o acknow ledge t hat crime as such does not exist ; t hat law breaking act s are het erogenous; t hat crime is cult urally and hist orically variable; t hat inf ract ion of law is common; t hat t hose arrest ed, charged and convict ed are not represent at ive of t hose w ho break t he law but a skew ed sample produced t hrough all sort s of social processes.’ 2 Consequent ly, it makes lit t le sense t o t alk of genes f or crime, or even genes f or part icular t ypes of ant isocial conduct , such as robbery or physical assault . Researchers in behavioural genet ics do not deny t his. Their research t ends t o f ocus on more narrow ly def ined and

1

Lombroso, C. (1876). L'Uomo Delinquent e. M ilan: Horpli.

2

Rose, N. (2000). The biology of culpabilit y: pat hological ident it y and crime cont rol in a biological cult ure. Theoret ical Criminology 4, 5–34.

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measurable t rait s such as impulsivit y, aggressiveness and psychiat ric disorders, such as conduct disorder and At t ent ion Def icit Hyperact ivit y Disorder (ADHD). Nonet heless, it may be t he case t hat our concept s of crime and ant isocial behaviour are so complex and socially and cult urally inf luenced t hat t hey w ill simply not be amenable t o scient if ic invest igat ion. 14.4 In t his chapt er, w e review biological explanat ions of crime and ant isocial behaviour t hat have been off ered in recent hist ory and consider t he implicat ions of research in behavioural genet ics f or our legal syst em. In part icular, w e consider t hree separat e areas of criminal just ice w hich may be aff ect ed by advances in research in behavioural genet ics: ■ Exculpat ion: Whet her genet ic inf ormat ion about a behavioural t rait should aff ect our at t ribut ions of legal responsibilit y, t hat is, as an exculpat ory f act or. ■ Sent encing: Whet her genet ic inf ormat ion about a behavioural t rait should aff ect t he w ay in w hich w e sent ence and t reat convict ed off enders. ■ Predict ion: Whet her genet ic inf ormat ion should be used t o predict t he f ut ure occurrence of ant isocial behaviour.

Previous genetic and physiological explanations of crime

XYY males 14.5 In 1965 a paper w as published based on research involving almost 200 males w ho had been commit t ed t o t he St at e Hospit al at Carst airs in Scot land.3 Seven of t he men w ere f ound t o have an ext ra Y chromosome, a much higher rat e t han w as t hought t o be t he case in t he general populat ion. The research raised t he possibilit y t hat t his genet ic abnormalit y could be relat ed t o t he aggressive behaviour of t he inmat es. Furt her research show ed t hat XYY males w ere more likely t o be t aller t han average and of low int elligence, but f ailed t o provide conclusive evidence about a link t o aggressive or violent behaviour.4 In 1976 a paper w as published w hich concluded t hat XYY males w ere more likely t o be imprisoned, but t hat t his w as due t o t heir low int elligence and low socioeconomic st at us w hich placed t hem at higher risk of being caught .5 The current st at e of opinion on t he XYY issue is t hat t here is insuff icient evidence t o est ablish any f irm link bet w een t he part icular genot ype and an increased risk of aggressive behaviour, alt hough t here does appear t o be an increased risk of off ending. 14.6 There are no legal cases in t he UK in w hich a genet ic diagnosis of XYY has been used t o est ablish a def ence. At least f ive major US cases at t empt ed t o use t he f act t hat t he accused w as XYY in def ence but none w as successf ul. In one, St at e v Robert s (1976), t he judge st at ed t hat ‘present ly available medical evidence is unable t o est ablish a reasonably cert ain causal connect ion bet w een t he XYY def ect and criminal conduct ’.6 We discuss t he issue of t he qualit y of scient if ic evidence t hat is admissible in t he legal syst em in paragraph 14.23.

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3

Jacobs, P.A. , Brunt on, M . , M elville, M . M ., Brit t ain, R. P. & M cClermont , W. F. (1965). Aggressive behaviour, ment al subnormalit y and t he XYY male. Nat ure 208, 1351–2.

4

Baker, D., Telf er M . A., Richardson, C. E. & Clark, G. R. (1970). Chromosome errors in men w it h ant isocial behavior: comparison of select ed men w it h ‘Klinef elt er's syndrome’ and XYY chromosome pat t ern. JAM A 214, 869–78; Jacobs, P. A., Price, W. H., Richmond, S. & Rat cliff , B. A. W. (1971). Chromosome surveys in penal inst it ut ions and approved schools. J. M ed. Genet . 8, 49–58; Schiavo, R. et al. (1984), Sex, chromosome anomalies, hormones and aggressivit y. Arch. Gen. Psychiat ry 4, 93–9.

5

Wit kin, H. A. et al. (1976). XYY and XXY men: criminalit y and aggression. Science 193, 547–55.

6

St at e v Robert s (1976). 14 Wash. App. 727, 544 P.2d 754.

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RESPO N SI BI LI TY

14.8 Numerous syndromes have been claimed t o w eaken or eliminat e moral responsibilit y in cases w here t he accused person pleads not guilt y by reason of insanit y. These include syndromes t hought t o arise as t he result of an environment al t rauma, f or example bat t ered spouse syndrome, bat t ered child syndrome and post -t raumat ic st ress disorder, and t hose t hought t o arise as t he result of a biological condit ion, such as premenst rual syndrome and post nat al depression. In t hese ‘biological syndromes’, t he argument is t hat chemical or hormonal changes in t he body aff ect ed t he individual’s capacit y t o cont rol t heir act ions t o such a degree t hat t hey cannot t ruly be said t o be responsible f or t hem. The def ence of premenst rual syndrome has been successf ul in Brit ain but is now rarely used because t here has been a subsequent increase in measures t o improve early det ect ion and prevent ion of t he condit ion.

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Syndromes

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14.7 It is perhaps w ort h making t he observat ion here t hat having just a single Y chromosome is highly correlat ed w it h criminal behaviour: t he vast majorit y of t he prison populat ion in t he UK are men. This correlat ion does not seem t o generat e t he same concerns, in t hat ‘being male’ is not suggest ed as somet hing t hat absolves individuals f rom responsibilit y f or criminal act s, nor is it t aken int o account as a mit igat ing f act or in sent encing. We consider t he relevance of t he f requency of a genet ic t rait or predisposit ion in t he populat ion w it h regard t o predict ing behaviour in paragraph 14.38.

CH A PTER

In t he case of XYY males, it is highly unlikely t hat t he syndrome w ill acquire legal signif icance because of t he diff icult y in show ing t hat it is direct ly linked t o f orms of ant isocial behaviour.

Genetics: Huntington’s disease 14.9 Hunt ingt on’s disease, a single gene disorder t hat may be associat ed in some cases w it h aggressive behaviour, has obvious implicat ions f or criminal law. A person w it h t his disorder may behave irrat ionally and may carry out assault s w it h no apparent mot ive.7 Such behaviour is, of course, more easily seen as a concomit ant of illness t han is t he case w it h asympt omat ic genet ic condit ions, and is t heref ore more likely t o be t reat ed by t he court s as an exculpat ory f act or. Prosecut orial discret ion of t en prevent s t he bringing of charges against a person suff ering f rom a diagnosed and obvious condit ion, such as dement ia, and it is f or t his reason t hat legal precedent s do not art iculat e t he implicat ions f or criminal guilt of such condit ions. The import ant point t o not e, how ever, is t hat it is not t he genet ic mut at ion w hich is regarded as exculpat ory here but it s impact on t he brain. If a person suff ering f rom Hunt ingt on’s disease w ere t o be acquit t ed of a criminal charge relat ing t o aggressive behaviour produced by t he condit ion, t hen t his w ould be on psychiat ric rat her t han on genet ic grounds.

Genetics: M onoamine oxidase A (M AOA) deficiency 14.10 As not ed in Chapt er 9, t here has been very lit t le research on individual genes t hat might inf luence ant isocial behaviour or criminal act ivit y, w it h t he except ion of t he f amily w hose

7

M ild psychot ic and behavioural problems can appear some years bef ore t he onset of t he disease. A st udy by Danish researchers in 1998 f ound increased prevalence of criminal behaviour in men w it h t he genet ic mut at ion t hat causes Hunt ingt on’s disease and concluded t hat t his w as linked t o t he personalit y changes t hat are of t en seen in people w it h t he condit ion (Jensen, P., Fenger, K., Bolw ig, T. G. & Sorensen, S.A. (1998). Crime in Hunt ingt on’s disease: a st udy of regist ered off ences among pat ient s, relat ives and cont rols. J. Neurol. Neurosurg. Psychiat ry. 65, 467–71).

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male members w ere def icient in a prot ein called M AOA. These males w ere f ound t o be more likely t o have been convict ed of aggressive crimes such as rape and arson. Since t his f inding is current ly conf ined t o members of one f amily, it seems unlikely t hat it w ill have an impact in t he legal syst em.8 How ever, as w e not ed in paragraph 9.25, one recent st udy has suggest ed t hat t he M AOA genot ype may be a relat ively eff ect ive predict or of ant isocial behaviour in children w ho are also malt reat ed.

Genetic information as an exculpatory factor 14.11 If an associat ion w ere t o be est ablished bet w een t he possession of a part icular genet ic variant and ant isocial behaviour of some sort , f or example, aggressive act s, it might be suggest ed t hat t his inf ormat ion could be used not only in an at t empt t o explain crime, but also t o excuse, or absolve f rom responsibilit y, t hose charged w it h criminal off ences. This possibilit y raises a challenge t o t he not ions of legal responsibilit y w hich underlie our syst em of criminal just ice. As w e observed in Chapt er 12, if it w ere t he case t hat responsibilit y f or our act s is a mat t er of ‘genet ic luck’, ant isocial behaviour w ould cease t o be a mat t er of personal responsibilit y as it w ould depend on f act ors beyond t he cont rol of t he individual. 14.12 While it is unlikely t hat genet ic explanat ions of behaviour w ill change t he f undament al assumpt ions on w hich criminal just ice relies, t hey could nonet heless have some eff ect . We should recall t hat , in t he past , new scient if ic insight s have been resist ed by t he court s, only t o be f ully acknow ledged w it h t he passage of t ime. One example here is t he t echnique of DNA f ingerprint ing. Anot her is t he readier accept ance of psychiat ric def ences in a number of West European count ries, w hich accompanied t he birt h and development of modern psychiat ry in t he second half of t he ninet eent h cent ury. This lat t er example, how ever, can also serve t o highlight t he diff icult ies t hat may arise w hen evidence f rom a new discipline is incorporat ed int o t he legal syst em. The disinclinat ion of t he court s t o accept part icular medical or scient if ic explanat ions should not be assumed. Equally, nor should t heir capacit y f or assessing t he validit y of novel scient if ic claims be overest imat ed. 14.13 Tradit ionally, t he criminal law bases it s not ions of responsibilit y on t he assumpt ion t hat every adult is answ erable f or his or her act s, and is host ile t o ideas w hich challenge t he exist ence of f ree w ill and individual responsibilit y. The law endorses t he idea of personal responsibilit y t hat lies behind t he w ay in w hich w e conduct our everyday lives in societ y, since t he very idea of punishment and ret ribut ion makes lit t le sense unless f ree w ill is assumed. ‘Very simply, t he law t reat s man’s conduct as aut onomous and w illed, not because it is, but because it is desirable t o proceed as if it w ere.’ 9 14.14 At t he core of criminal responsibilit y is t he not ion t hat human act ion consist s of an act and an accompanying ment al st at e, usually an int ent ion on t he part of t he individual. Wit h t he except ion of of f ences of st rict liabilit y (regulat ory of f ences in w hich t he st at e of mind of t he accused has no bearing on liabilit y), t he ment al element behind act ion is of great import ance in t he law. The criminal law is not usually concerned w it h mot ive, at least f or t he purposes of allocat ing responsibilit y. What mat t ers is t he at t it ude of t he individual t ow ards t he act it self . If an act is int ent ional, or perf ormed recklessly or w it h

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8

In M obley v St at e (1995). 265 Ga. 292, 455 S.E. 2d 81 t he def ence law yers of a man accused of murder at t empt ed t o have t heir client t est ed f or M AOA def iciency. How ever, t he court ref used t o allow such a t est , saying t hat ‘t he t heory of genet ic connect ion … is not at a level of scient if ic accept ance t hat w ould just if y it s admission’. The request w as made as a pot ent ial mit igat ing f act or, not an exculpat ory f act or, in an at t empt t o avoid t he deat h penalt y.

9

Packer, H. (1968). The Limit s of t he Criminal Sanct ion. St anf ord: St anf ord Universit y Press.

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LEGA L RESPO N SI BI LI TY

14.16 An exponent of a ‘genet ic def ence’ might argue t hat t he reason w hy a person has commit t ed t he criminal off ence in quest ion is t hat a genet ic variant has eit her caused t he behaviour in an immediat e sense (in t he same w ay as an elect rical st imulus may produce a muscular react ion), or because t he genet ic variant has cont ribut ed t o t he development of a personalit y, or, in moral t erms, a charact er (or set of disposit ions) w hich are manif est ed in cert ain f orms of act ion. These are dist inct claims, and it is t he second, more common line of argument w hich w e shall address here. This claim maint ains t hat because genes play a role in t he emergence of disposit ions, and t hese disposit ions in due course play a role in t he perf ormance of act s, our act s are not just t he product of w hat ever choices w e have made, but are produced by f act ors w hich w e did not choose and f or w hich w e are not t heref ore responsible. We have already discussed t his issue in it s philosophical cont ext in Chapt er 12; our concern here is t o consider how such an argument might be int egrat ed w it h exist ing t heories of criminal def ence.

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14.15 Not all act ions w hich inf ringe t he criminal law w ill at t ract liabilit y. Act ions perf ormed w it hout a relevant accompanying ment al st at e, such as act s perf ormed in a st at e of unconsciousness, f or example (aut omat ic act s), w ill not result in liabilit y. Def ences are also available t o t hose w ho are aff ect ed by a ment al disorder or syndrome. It is t his lat t er cat egory of def ences t hat is relevant t o t he debat e regarding behavioural genet ics.

CH A PTER

culpable negligence, t hen t he individual may be held responsible f or it unless a valid def ence is ident if ied and accept ed. In most cases, t hen, t he law is concerned w it h choice. We make f ree choices w it h regard t o our act ions, and w e t hen answ er f or t hese choices as f ree individuals.

14.17 An obvious analogy can be made t o personalit y disorder, since a personalit y disorder and t he possession of a genet ic variant predisposing t o ant isocial conduct (if such charact erist ics w ere t o be ident if iable) might be view ed as similar condit ions. How ever, it must be remembered t hat personalit y disorders are psychiat ric condit ions w hich cannot be said t o f all w it hin t he range of normal variat ion. A predisposit ion t o behave aggressively or impulsively does not necessarily ent ail t hat an individual has a disorder. We recall t he normal dist ribut ion curve explained in Chapt er 3 (Figure 3.3): it is axiomat ic t hat w it h such a dist ribut ion half t he populat ion w ill have an above-average score f or a part icular t rait . M oreover, t he point at w hich t he normal range becomes an ext reme score or a disorder is never clear. Thus, genet ic inf luences on t rait s such as aggression or impulsivit y may have implicat ions not just f or t hose w it h psychiat ric disorders, but f or ot her individuals accused of ant isocial behaviour. 14.18 Wit h regard t o individuals w it h personalit y disorders and t hose t hought t o have an increased risk of ant isocial behaviour as a result of a genet ic variant , t here is no quest ion of individual responsibilit y f or t he occurrence of t he condit ion or disposit ion. In bot h cases, t he condit ion is a background against w hich a decision t o act in a part icular w ay is made. The decision t o ignore t he condit ion as a possible exculpat ory f act or might t heref ore be reached on t he same basis. A person w ho has a psychopat hic personalit y disorder may claim t hat his or her ant isocial act ions are t he product of a condit ion f or w hich he or she is not responsible. The psychopat h does not choose t o be a psychopat h. What ever view is t aken of t he aet iology of t his condit ion, t he psychopat hic personalit y is probably shaped at an early age and it is generally not regarded as somet hing w hich t he individual is able t o change. The psychopat h cannot t heref ore be blamed f or being a psychopat h, even if t here is room f or blame in respect of his or her conduct . How ever, in

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pract ice, w e do generally regard persons w it h a psychopat hic personalit y disorder as being responsible f or t heir act ions, even if w e may accept t hat it is more diff icult f or t hem t o comply w it h social and moral rest raint s. Cert ainly, as f ar as t he law is concerned, in spit e of some cases in w hich psychopat hic personalit y disorder has been admit t ed as grounds f or a plea of diminished responsibilit y, t he pref erred approach of t he court s is t o t reat such individuals as ordinary off enders. 14.19 The psychopat h is considered t o be responsible f or legal purposes, because t o hold ot herw ise w ould undermine t he assumpt ions about responsibilit y w hich need t o be made in societ y. We have not ed above t hat w hat ever t he claims of det erminism may be in t he moral domain, w e order our social and moral lives on an assumpt ion t hat individual responsibilit y f or act ions does exist . Quit e apart f rom t hese grounds, pragmat ic considerat ions point t o a need t o limit exculpat ory condit ions. If t he scope of available excuses, w het her genet ic or environment al, is t oo broad, t hen it w ould be only t oo easy f or a def endant in a criminal t rial t o claim t hat t he behaviour w as not his or her ow n but w as det ermined by past experiences and inf luences. The impract icalit y of such an approach is self -evident , and w ould seriously compromise our social arrangement s. It w ould remove, in eff ect , t he need t o make any moral eff ort t o comply w it h societ y’s rules; everyt hing w ould be pot ent ially excusable. This pot ent ial w eakening of t he just ice syst em is a vit al considerat ion in examining w het her genet ic inf luences on behaviour in t he normal range ought t o be t aken int o account in at t ribut ing responsibilit y. 14.20 Regardless of w het her a predisposit ion is derived f rom genet ic or non-genet ic inf luences, t he crucial quest ion is w hat is t he st at us of t hat predisposit ion in t he legal cont ext ? One response might be t hat t he relevant quest ion t o ask of a person w it h an alleged genet ic disposit ion t o a t rait is ‘w as t he predisposit ion so st rong he or she could not resist it ?’ This raises immediat e problems concerning w hat const it ut es an irresist ible predisposit ion and how such a t hing could be measured. M ore f undament ally, it does not seem plausible t hat genet ic inf luences on ant isocial behavioural t rait s w ill generat e irresist ible predisposit ions. Rat her, genet ic and ot her f act ors may cont ribut e t o our charact ers in w ays t hat make cert ain behaviours more or less likely, rat her t han cert ain. If t his is so, w hat should w e say about a genet ic predisposit ion t o impulsivit y w hich makes it more diff icult f or a part icular individual t o avoid act ing aggressively t han it is f or ot her people? In such a case, resist ance t o t he predisposit ion w ould not be impossible, just considerably more diff icult t han average. Should t his be t aken int o account w hen blaming an individual f or t heir behaviour? It has been argued by various philosophers t hat t hose t o w hom virt uous behaviour comes nat urally are less deserving of praise t han t hose f or w hom such behaviour requires great self -rest raint and eff ort . M ight a similar argument be made t o t ake account of t he great er eff ort required by t he ‘less nat urally virt uous’ individual’s st ruggle against his or her charact er t rait s? The quest ion of how diff icult it is f or us t o cont rol our behaviour as a result of genet ic inf luences w ill be import ant in t he cont ext of t he sent encing and t reat ment of off enders, w hich w e discuss in paragraphs 14.26-14.33 below. 14.21 Charact erist ics t hat are inf luenced by genet ic variat ion and are w it hin t he range of normal variat ion cannot be considered t o amount t o an illness or, indeed, an abnormalit y. This w ould suggest t hat t hey are out side t he scope of t he exist ing legal excuses of insanit y or diminished responsibilit y. This is quit e consist ent w it h t he not ion t hat criminal law does not pay at t ent ion t o t he range of abilit ies or charact erist ics w hich def endant s may have, out side t he very limit ed def ence of provocat ion. Irascibilit y or inabilit y t o resist t empt at ion are not charact erist ics w hich t he court s w ould t ake int o account in det ermining

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CH A PTER

responsibilit y. This is because t he criminal law relies on a single st andard of conduct w hich is expect ed of all. To allow individual charact erist ics and capacit ies t o aff ect responsibilit y w ould dest abilise t he criminal just ice syst em and w ould be regarded as unaccept able and unf air by t he public. This t heref ore precludes a role in responsibilit y f or any genet icallyassociat ed charact erist ic w it hin t he normal range.

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14.22 Could it be argued t hat a genet ic predisposit ion t o ant isocial behaviour ought t o be def ined as a disorder, and t heref ore, t hat it should act t o lessen responsibilit y in t he same w ay t hat some psychiat ric disorders are recognised as ent ailing diminished responsibilit y? This w ould be an example of medicalisat ion, w hich w e discussed in paragraphs 13.13–13.24. If a part icular genot ype has not manif est ed it self in sympt oms of illness, t hen in ordinary language w e w ould probably not describe t he person as being ill, even if w e w ere t o say t hat t hey w ere aff ect ed by a part icular condit ion. This w ould t heref ore act against any at t empt t o bring t he possession of a part icular genot ype int o t he cat egory of an exculpat ory illness. To say t hat a person is ill because he or she has a part icular genet ic make-up w hich may be associat ed w it h ant isocial behaviour is count er-int uit ive. Only w hen t he genot ype has manif est ed it self sympt omat ically and given rise t o ident if iable physical pat hology or psychiat ric illness w ill w e say t hat t he person is ill and t heref ore pot ent ially not responsible f or his or her conduct . For t his reason, genet ic f act ors w ill only current ly be relevant in so f ar as t hey are product ive of ot her ident if iable condit ions: in t hemselves t hey do not amount t o t he excusing condit ion. For example, if t he responsibilit y of a schizophrenic person w ere t o be at issue, it w ould make no diff erence w het her t he illness w ere t o be at t ribut ed t o a genet ic f act or or t o an environment al f act or. The individual w ould be excused on t he grounds of t he illness, not it s cause. 14.23 A f urt her problem w it h t he use of inf ormat ion about genet ic variant s t hat inf luence behaviour, at least f or t he f oreseeable f ut ure, is t he degree t o w hich a causal link can be est ablished bet w een a part icular genet ic t rait and a part icular criminal act . In t he US, it w as previously t he case t hat scient if ic, medical or psychiat ric evidence had t o be generally accept ed w it hin t he relevant academic communit y. Follow ing a landmark case in 1993, t he posit ion in t he US is now t hat evidence must be relevant and reliable, but does not have t o be generally accept ed. Of course in pract ice it seems likely t hat relevant and reliable evidence w ill of t en also be generally accept ed.10 In Brit ain, t he posit ion is similar, in t hat relevance and reliabilit y are t he key crit eria by w hich evidence is assessed f or admissibilit y.11 It seems likely t hat behavioural genet ics, if it ident if ies genet ic inf luences on behaviour, w ill be able t o do no more t han off er evidence of correlat ions of varying st rengt hs bet w een part icular genet ic variant s and broad cat egories of ant isocial behaviour. It is unlikely t hat such correlat ions w ould be view ed by t he legal syst em as suff icient ly reliable t o w arrant excusing an off ender. 14.24 We conclude t hat research in behavioural genet ics does not pose a f undam ent al challenge t o our not ions of responsibilit y as t hey are applied in t he legal cont ext . We consider t hat genet ic variant s in t he norm al range are unlikely t o be considered an excuse f or legal purposes, at least f or t he f oreseeable f ut ure. They f all out side t he scope of t he def ences of insanit y and dim inished responsibilit y and cannot be said t o absolve individuals f rom responsibilit y f or t heir act ions.

10

Daubert v M errell Dow Pharmaceut icals Inc. (1993). 509 US 579.

11

See, f or example, R v Robb. (1991). 93 Cr App Rep 161 at 166; R v M ohan. (1994).2 SCR 9.

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14.25 If progress in behavioural genet ics w ere t o be such t hat close and clearly ident if iable associat ions bet w een part icular genet ic variant s and part icular f orms of ant isocial act s w ere t o be demonst rat ed, t here w ould be a case f or a re-examinat ion of t he legal implicat ions. It might be t hat t he concept of diminished responsibilit y, f or example, could be expanded t o embrace such condit ions, perhaps by redef ining view s of illness. If t his possibilit y w ere t o be considered, t hought w ould have t o be given t o t he pot ent ial dangers of unw arrant ed over-reliance on genet ic inf ormat ion and t he consequences of reducing responsibilit y f or our act ions.

Sentencing and treatment of offenders 14.26 Responsibilit y is one t hing; t he quest ion of w hat t o do w it h t he convict ed off ender is anot her. Fut ure insight s of behavioural genet ics might play a great er role in t he punishment of off enders. At t his st age of t he criminal process it is possible t o t ake a much broader view of t he background of an off ence and t he person w ho commit s it . Current ly, def ence law yers submit a w ide range of inf ormat ion about t he off ender and his or her background and circumst ances t o t he judge, w ho can choose w het her or not t o t ake it int o account in det ermining t he appropriat e sent ence (w it hin t he exist ing const raint s on sent encing). Ot her f act ors, such as public saf et y, are also import ant considerat ions. There are all sort s of f eat ures of individuals f or w hich a correlat ion w it h ant isocial and criminal behaviour has been suggest ed. For example, in t he cont ext of juvenile delinquency, report ed risk f act ors include povert y, being born t o a t eenage mot her, being reared in a f amily w it h at least f our children, being adopt ed, having divorced parent s and having an aggressive f at her.12 14.27 The mechanisms by w hich such environment al f act ors inf luence suscept ibilit y t o ant isocial behaviour are not w ell underst ood, but evidence of such correlat ions exist s, and may inf luence a judge’s sent encing decision (alt hough t here is an increasing number of crimes f or w hich sent encing const raint s exist , such as mandat ory lif e sent ences f or murder, aut omat ic lif e sent ences f or serious repeat crimes and minimum sent ences in ot her areas such as burglary and drug t raff icking). Judges are permit t ed t o t ake int o account , w hen sent encing, inf ormat ion about t he circumst ances of an off ence and any aggravat ing and mit igat ing f act ors t hat may be relevant . Relevant circumst ances can include inf ormat ion about t he age and vulnerabilit y of t he vict im, t he off ender’s previous criminal record, t he ext ent t o w hich t he crime w as premedit at ed, and t he off ender’s mot ive. M it igat ing f act ors can be t aken int o account t o ref lect an individual’s enhanced or diminished culpabilit y f or a crime, or because t he judge believes t hat a milder sent ence may be suff icient t o discourage t he off ender f rom commit t ing f urt her crimes. An off ender may be judged t o have diminished culpabilit y because of provocat ion or t empt at ion, ment al disorder, st ress or t he eff ect of medicines, narcot ics or alcohol. Judges can also t ake int o account evidence t hat an off ender is of good charact er, w hich is usually det ermined on t he basis of a lack of previous convict ions.13 It is less clear t o w hat ext ent judges acknow ledge t he inf luence of environment al f act ors t hat are st at ist ically correlat ed w it h an increased likelihood of ant isocial behaviour, such as povert y, f amily size and so on (see paragraph 14.26).

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12

See Rut t er, M ., Giller, H. & Hagell, A. (1998). Ant isocial Behaviour by Young People. Cambridge: Cambridge Universit y Press, f or a comprehensive summary of t hose risk f act ors relat ing t o juvenile delinquency.

13

There are numerous ot her f act ors t hat can be considered in mit igat ion. For f urt her det ail of t hose ment ioned and addit ional f act ors, see Walker, N. & Padf ield, N. (1996). Sent encing: Theory, Law and Pract ice. 2nd ed. London: But t erw ort hs. See also t he w ork of t he Sent encing Advisory Panel w hich provides advice t o t he Court of Appeal ht t p://w w w.sent encing-advisorypanel.gov.uk/ (8 July 2002).

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RESPO N SI BI LI TY

‘if ant isocial conduct is inscribed in t he body of t he off ender, it seems t hat it is mit igat ion of punishment t hat is required but t he long-t erm pacif icat ion of irredeemable individual in t he name of public prot ect ion, even if t his means reject ion of many rule of law considerat ions, such as t hose concerning proport ionalit y of crime and punishment .’ 15

LEGA L

14.30 If a genet ic predisposit ion is ident if ied in an off ender, how might t his inf ormat ion be int erpret ed in t he cont ext of sent encing? One possibilit y is t hat t he off ender w ill be seen as less account able f or his/her act s and t heref ore less deserving of punishment . But anot her possibilit y is t hat t he off ender w ill be seen as more likely t o off end and less likely t o be successf ully rehabilit at ed. Nikolas Rose has suggest ed t hat :

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14.29 The idea t hat f act s about an individual’s environment can aff ect t he ext ent t o w hich t hey should be punished f or criminal act s cont ains an implicit assumpt ion t hat individuals have essent ially sound charact ers, but t hat unavoidable ext ernal inf luences t hey did not choose can have a negat ive eff ect on t hem. In cont rast , if genet ic inf ormat ion about an individual’s suscept ibilit y t o ant isocial behaviour is accept ed, it seems t o imply t hat t he individual has essent ially an unsound, or at least , a less sound charact er. We not ed earlier (paragraph 14.20) t hat , given a part icular background or environment al cont ext , a genet ic predisposit ion t o impulsive behaviour, f or example, might mean t hat an individual f inds it harder t han ot hers do t o cont rol his/her act ions.

CH A PTER

14.28 Should inf ormat ion about genet ic f act ors t hat are correlat ed t o a similar degree w it h ant isocial behaviour also be admissible? Jonat han Glover has observed t hat it is ‘unclear t hat t here is anyt hing radically diff erent about explanat ions w here t he causal st ory goes back t o t he genes and explanat ions w here t he causal st ory goes back t o early environment .’ 14 But w hat might be t he implicat ions of w idening admissible f act ors t o include genet ic inf ormat ion?

not t he t he t he

Such a concern w ould be misguided in t he case of behavioural genet ics, because, as w e have st ressed t hroughout t his Report , t he eff ect s of genes are not immut able. Genet ic inf luences on t rait s such as impulsivit y and aggression cannot make us an ‘irredeemable individual’ because t he eff ect s of our genes are not inevit able. 14.31 In t he case of ant isocial behaviour, various w ays of reducing t heir inf luence may be available. Pot ent ial int ervent ions might include cognit ive t herapy and programmes in self -cont rol and anger management . Ot her pot ent ial int ervent ions such as gene t herapy or medical t reat ment s might also be possible. We t ook t he view in Chapt er 13 t hat , prima f acie, t he applicat ion of each of t he t hree cat egories of int ervent ion might be just if ied. How ever, w e also not ed t hat t he use of genet ic and medical int ervent ions may be less desirable f or a number of reasons. First , regarding genet ic int ervent ions, t he saf et y of t echniques such as gene t herapy is liable t o be low er. Secondly, if an individual has a genet ic predisposit ion t o aggression or impulsivit y, it is likely t hat t his w ill be manif est ed in response t o cert ain environment al sit uat ions. The unw ant ed conduct w ill

14

Glover, J. The implicat ions f or responsibilit y of possible genet ic f act ors in t he explanat ion of violence. In Bock, G. R. & Goode, J. A., edit ors. (1996). Symposium on Genet ics of Criminal and Ant isocial Behaviour, Ciba Foundat ion 194. Chichest er, UK: Wiley.

15

Rose, N. (2000). The biology of culpabilit y: pat hological ident it y and crime cont rol in a biological cult ure. Theoret ical Criminology 4, 5–34.

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t end t o occur at isolat ed int ervals and might t heref ore be amenable t o int ervent ions t hat t arget t he behaviour as it occurs, rat her t han t hose t hat at t empt t o alt er t he individual’s underlying charact er. Such int ervent ions might be more ef f ect ive, but it is likely t hat cases w ould have t o be assessed individually, w it h ref erence t o t he f act ors ident if ied in Chapt er 13 (see paragraph 13.26) bef ore a judgement could be made about t he most suit able course of act ion. 14.32 We conclude t hat , w it h regard t o t he sent encing of convict ed off enders, t he crim inal law should be recept ive t o w hat ever valid psychiat ric and behavioural evidence is available. The t aking int o account of genet ic f act ors w ould depend on t he degree t o w hich such evidence is convincing and relevant . Credible evidence of inf luence and a robust t est f or t he genet ic f act or in quest ion w ould be essent ial: t he w eight t o be accorded t o such inf orm at ion w ould be det erm ined by t he judge. Current ly, environment al, social and psychiat ric assessment s may be t aken int o account by judges in det ermining appropriat e sent ences. These must also be support ed by valid, accurat e and reliable evidence. It w ould be unw ise t o assume t hat genet ics w ill not be able t o assist in det ermining degrees of blame, even if t he ‘all-or-not hing’ quest ion of responsibilit y is not aff ect ed by genet ic f act ors t hemselves. Such a role w ould not compromise basic assumpt ions as t o responsibilit y. 14.33 Exchanges bet w een genet ics and t he criminal law are at present not very product ive given t he uncert ain nat ure of t he evidence. This is likely t o change. We recom m end t hat t he crim inal just ice syst em should be open t o new insight s f rom disciplines t hat it has not necessarily considered in t he past . The regular exchange of ideas in t his area bet w een researchers in behavioural genet ics, crim inologist s and law yers could be an eff ect ive m eans of ensuring t hat legal concept s of responsibilit y are assessed against current evidence f rom t he behavioural and m edical sciences.

Predictive use of genetic information 14.34 Criminal just ice adheres t o t he not ion t hat liabilit y and result ing punishment should alw ays be based on specif ic and proven inst ances of misconduct . In t he f ut ure, how ever, it is possible t hat genet ic inf ormat ion could be used, eit her on it s ow n, or in conjunct ion w it h inf ormat ion about environment al inf luences, in an at t empt t o show t hat an individual is likely t o exhibit ant isocial behaviour, even if he or she has not yet commit t ed a crime and indeed may never do so. 14.35 Current ly, at t empt s t o predict f ut ure behaviour can play a role in t he criminal just ice syst em, but only in respect of decisions as t o t he f ut ure t reat ment of a person w ho has already commit t ed an off ence. Even in t his limit ed cont ext , it is import ant t hat claims as t o abilit y t o predict f ut ure behaviour are subject ed t o close scrut iny. At present t he accuracy of such predict ions – usually made on a psychiat ric basis – is a mat t er of cont roversy. Where t hese are used as t he basis of decisions t o det ain individuals on ment al healt h grounds, t hey raise major issues of civil libert y and of t he pot ent ial abuse of psychiat ric disposal as a means of cont rol. 14.36 In cases w here t he individual in quest ion has not exhibit ed ant isocial behaviour or been convict ed of a crime, at t empt s t o predict t he likelihood of such behaviour in t he f ut ure raise even great er concerns. In 1999, t he UK government init iat ed consult at ion on t he t reat ment of individuals w it h severe personalit y disorder. One opt ion set out w as t he int roduct ion of ‘pow ers f or t he indet erminat e det ent ion of dangerous severely personalit y

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1 4 LEGA L RESPO N SI BI LI TY

14.37 Despit e t he cont roversy over w het her t here is such a disease as ‘severe personalit y disorder’, it is f air t o say t hat t he est imat ed 2000 individuals in Brit ain t hought t o have t he condit ion are t hose w ho display t he ext remes of behaviour, and w ould be most unlikely t o f all w it hin t he range of normal variat ion. Could t he use of genet ic inf ormat ion t o predict t he behaviour of t hose w ho do lie w it hin t he normal range be just if ied? Furt her, could t he use of genet ic inf ormat ion in conjunct ion w it h ot her inf ormat ion, such as t hat concerning environment al inf luences on behaviour, f or t he predict ion of ant isocial behaviour be just if ied?

CH A PTER

disordered people in bot h criminal and civil proceedings. Those det ained under t he new orders w ould be managed in f acilit ies run separat ely f rom prison and healt h service provision. The locat ion f or det ent ion w ould be based on t he risk t hat t he person represent ed and t heir t herapeut ic needs rat her t han w het her t hey had been convict ed of an off ence.’ 16 Concern w as w idely expressed at t he suggest ion t hat individuals might be det ained w it hout having commit t ed a crime, and f urt hermore, t hat t his decision might be based on t he diagnosis of a cont roversial psychiat ric disorder.17 In t his Report , w e have of t en draw n at t ent ion t o t he blurred line bet w een behaviour in t he normal range and t hat w hich is considered a disorder. The case of ‘severe personalit y disorder’ is an import ant illust rat ion of t he risks of basing public policy on classif icat ions and diagnoses w hich are not clearly def ined and are not t he subject of consensus among medical prof essionals.18

14.38 As f ar as t he use of genet ic inf ormat ion as a sole predict or of ant isocial behaviour is concerned, it is unlikely t hat such inf ormat ion w ill be of suff icient accuracy t o just if y it s use. Consider a hypot het ical genet ic variant t hat is present in 30% of t he populat ion and conf ers a f ive-f old increase in t he probabilit y of an individual commit t ing a criminal act . If t hat act w ere common – say 5% of t he t ot al populat ion w as expect ed t o commit t he act in t he f ut ure – t hen of t hose in t he populat ion w it h t he ‘at risk’ genot ype only 11% could be expect ed t o commit t he criminal act . Nearly nine out of t en individuals ‘at risk’ could be expect ed not t o off end. M oreover, nearly one t hird of t he individuals w ho subsequent ly commit t he crime w ould have t he ‘low -risk’ genot ype.19 14.39 How ever, it may be t hat by combining inf ormat ion about environment al and genet ic inf luences on ant isocial behaviour w it h regard t o a part icular individual, a more accurat e predict ion is possible. Alt hough, as w e have repeat edly st ressed in t his Report , t he eff ect s of genes are not inevit able, inf ormat ion about genet ic and environment al inf luences may generat e st at ist ical inf ormat ion relat ing t o t he chance of a part icular individual exhibit ing ant isocial behaviour t hat may be t hought suff icient t o w arrant int ervent ion. In t he case of children, at t empt s are already made t o predict w het her an individual w ho has not already done so is likely t o exhibit ant isocial or criminal behaviour in t he f ut ure. In t he UK, early 16

Home Off ice, M anaging dangerous people w it h severe personalit y disorder: proposals f or policy development . ht t p://w w w.homeoff ice.gov.uk/cpd/persdis.pdf (8 July 2002).

17

For example, in an art icle in t he Guardian new spaper, t he president of t he Royal College of Psychiat rist s, Dr M ike Shoot er, said t hat dangerous severe personalit y disorder w as ‘a diagnosis w hich does not exist anyw here in t he w orld’ (Boseley, S. (2002). Psychiat rist s t o join prot est over bill. The Guardian 29 July). The edit or of t he Journal of Forensic Psychiat ry has observed t hat dangerous severe personalit y disorder ‘is not a recognised t erm in psychiat ry or psychology’ (Buchanan, A. & Leese, M . (2001). Det ent ion of people w it h dangerous severe personalit y disorders: a syst emat ic review. Lancet 358, 1955–9).

18

Specif ic ref erence t o ‘severe personalit y disorder’ is not included in t he draf t M ent al Healt h Bill w hich is being considered by t he UK government in 2002. How ever, t his Bill does allow f or t he det ent ion of an individual w it h a serious ment al healt h problem w hich is not amenable t o t reat ment (in ot her w ords, a serious personalit y disorder) and w ho is judged t o be a signif icant risk t o ot hers, even in t he absence of a criminal convict ion.

19

One st udy concerning dangerous severe personalit y disorder has suggest ed t hat in order t o prevent one person w it h dangerous severe personalit y disorder f rom commit t ing a violent act , six people w ould have t o be det ained, because of t he diff icult y in making accurat e predict ions of behaviour. The aut hors not e t hat ‘t he decision as t o w hat rat e of error should be deemed accept able f rom t he point of view of prevent ive det ent ion is ult imat ely a moral one.’ (Buchanan, A. & Leese, M . (2001). Det ent ion of people w it h dangerous severe personalit y disorders: a syst emat ic review. Lancet 358, 1955–9).

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int ervent ion programmes t arget ‘at risk’ groups in order t o provide environment al int ervent ions.20 These int ervent ions are aimed at benef it ing t he individual concerned, and t hereby indirect ly benef it ing societ y. This is a very diff erent sit uat ion f rom one in w hich an individual is det ained against his or her w ill in t he int erest s of societ y. What argument s can be made against including t he use of genet ic inf ormat ion in current pract ice? 14.40 As a st art ing point , it must be f irmly acknow ledged t hat at t empt s t o ident if y classes of pot ent ial off enders w ould off end t he presumpt ion of innocence w hich w e make of our f ellow cit izens and w hich underlies principles of equalit y. This applies bot h t o predict ions based on genet ic inf ormat ion and on inf ormat ion about environment al f act ors. How ever, t his presumpt ion of innocence must also be balanced against t he need t o ensure a saf e societ y. Since no predict ion using eit her genet ic or environment al f act ors w ill be inf allible, t here must be very good reasons f or encroaching on t he presumpt ion of innocence. One such reason might be t he possibilit y of an int ervent ion t hat w ould reduce t he likelihood t hat ant isocial behaviour w ould be displayed. 14.41 A st rong argument against t he use of such genet ic inf ormat ion w it hout t he consent of t he individual in quest ion is t hat conduct ing a genet ic t est might be seen as an unjust if ied invasion of privacy.21 Wit h regard t o t he t est ing of adult s, it is permissible in ext reme circumst ances t o subject people t o compulsory diagnost ic procedures, but t hese are st rict ly limit ed by law. It is unlikely t hat genet ic t est ing of people w ho have not been convict ed of any crime w ould f all w it hin t he boundaries of any current ly permissible cat egory. Wit h regard t o t he predict ive t est ing of children, it is f irmly enshrined in law and pract ice t hat medical int ervent ions in children must be f or t heir benef it , t hat is, in t heir best int erest s. For t his reason, predict ive genet ic t est ing of children f or lat e-onset diseases is not undert aken unless it is required t o enable early int ervent ion.22 14.42 Despit e current at t it udes t ow ards t he predict ive t est ing of children, it might be suggest ed t hat children should be t est ed t o discover w het her t hey are likely t o exhibit ant isocial behaviour, perhaps as part of a st rat egy f or reducing juvenile ant isocial behaviour. We not ed t hat one st udy has suggest ed t hat children w it h a part icular genot ype may be at higher risk of exhibit ing ant isocial behaviour if t hey are exposed t o abusive parent ing (paragraph 9.25 and paragraph 14.10). If t his result w ere f ound t o be reliable, it might be suggest ed t hat children should be t est ed f or t he relevant genot ype in order t hat part icular at t ent ion could be direct ed at t heir f amily environment if required. 14.43 M edical t est s on children not compet ent t o give consent require t he consent of t he parent or ot her adult legally ent it led t o give consent on behalf of t he child. Such consent is only valid if it is in t he best int erest s of t he child. It is possible t hat t est ing linked t o environment al int ervent ions, and indeed medical int ervent ions, could be described as being in t he best int erest s of t he child. How ever, a case could be made against t his

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20

One int erest ing programme is t he charit y Communit ies t hat Care, w hich is f unded by t he Joseph Row nt ree Charit able Trust and aims t o build saf er neighbourhoods by t arget ing risk f act ors in t he lives of children (w w w.communit iest hat care.org.uk (11 July 2002)). The programme is based on a US scheme t hat aims t o reduce ant isocial behaviour among children by reducing risk f act ors and increasing prevent ive f act ors. Risk f act ors are ident if ied at t he level of t he communit y, school, f amily and individual. While medical or genet ic f act ors are not considered, it is possible t o imagine a similar rat ionale being put f orw ard f or t heir use.

21

There is a grow ing body of int ernat ional bioet hical norms w hich specif ically prohibit non-consensual genet ic t est ing, on t he grounds t hat it const it ut es an invasion of t he right t o privat e lif e. These int ernat ional convent ions are out lined in Box 15.1.

22

Older children w ho are f ound compet ent t o consent may be t est ed predict ively f or lat e-onset diseases or f or carrier st at us on t heir request .

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14.44 We t ake t he view t hat w hile t he reduct ion of ant isocial behaviour and crime are import ant goals, any at t empt t o predict t he behaviour of an individual w ho has not exhibit ed ant isocial behaviour, and t o int ervene accordingly, poses a signif icant t hreat t o civil libert ies and should be t reat ed w it h great caut ion. The use of predict ive genet ic t est s t o ant icipat e ant isocial behaviour f or t he purposes of prevent ive act ion in t he case of individuals w ho have not already exhibit ed such behaviour raises et hical quest ions about balancing t he int erest s of individuals against t hose of societ y. We consider t hat t he predict ive use of genet ic inf orm at ion about behaviour in t he norm al range, used in isolat ion in t he case of individuals w ho have not exhibit ed ant isocial behaviour, is unlikely t o be w arrant ed because t he predict ive pow er of such inf orm at ion is likely t o be w eak and t here is a risk of f alse predict ions. How ever, w e t ake t he view t hat t he use of such inf orm at ion in conjunct ion w it h inf orm at ion about ot her, non-genet ic inf luences on behaviour m ay be just if ied if t he aim is t o benef it t he individual, and in doing so, t o benef it societ y also. We recom m end t hat t he predict ion of behaviour w it h a view t o det aining an individual w ho has not com m it t ed a crim e is not just if ied, w het her such predict ions are based on inf orm at ion about genet ic or non-genet ic inf luences on behaviour.

CH A PTER

argument on t he grounds of privacy and of st igma. It can be argued t hat children have t he same right t o genet ic privacy as do adult s and t hat t here are t heref ore limit at ions t o t he circumst ances in w hich general diagnost ic t est ing of children should be aut horised. If st igmat isat ion based on know ledge about genet ic inf luences on behaviour is great er t han t hat w hich may arise in response t o know ledge about environment al inf luences, t his could provide a reason f or allow ing predict ion based on environment al inf ormat ion only. Addit ionally, it might be argued t hat int ervent ions aimed at t hose w ho are more likely t o exhibit ant isocial or criminal behaviour, w hich rely on inf ormat ion about environment al f act ors, t end t o t arget groups, such as classrooms, schools or communit ies, rat her t han singling out individuals, and are t hus less problemat ic t han t hose t hat w ould also make use of genet ic inf ormat ion t o t arget int ervent ions at specif ic individuals. How ever, in bot h cases, it is ult imat ely t he case t hat int ervent ions are aimed at individuals.

Conclusion 14.45 In t his chapt er, w e have considered t hree diff erent w ays in w hich inf ormat ion about genet ic inf luences on behaviour may be used in t he criminal just ice syst em: t o absolve an individual f rom responsibilit y; as a mit igat ing f act or in sent encing an individual w ho has been convict ed of a crime; and t o predict t he likelihood t hat an individual w ill exhibit ant isocial behaviour in t he f ut ure, w hen he or she has not already done so. In t he f irst case, w e concluded t hat genet ic inf luences on behaviour in t he normal range should not absolve an individual f rom responsibilit y f or t heir behaviour. In t he second, w e concluded t hat , in t he same w ay t hat environment al f act ors may be t aken int o account in mit igat ion, genet ic f act ors could play a similar role, depending on t he reliabilit y and accuracy of t he inf ormat ion. Wit h regard t o predict ive t est ing, w e concluded t hat neit her genet ic nor nongenet ic inf ormat ion should be used t o predict f ut ure behaviour w it h a view t o det aining an individual w ho has not been convict ed of a crime. How ever, w e suggest ed t hat , if such inf ormat ion could be used f or t he benef it of t he individual, f or example, as a reason f or improving part icular environment al condit ions, t his may be just if ied. We also recommended t hat genet ic inf ormat ion should not be used in isolat ion in such cases.

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Chapter Test ing and select ion in employment , educat ion and insurance

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I N SU RA N CE

See Finkin, M . W. (2000). From anonymit y t o t ransparency: screening t he w orkf orce in t he inf ormat ion age. Colum. Bus. L. Rev. 2000, 403–51, at pages 417–26 and 447–51 f or a review.

A N D

3

ED U CATI O N

CIPD. (2001). Fif t h Annual Report on UK Recruit ment Pract ices. Personalit y quest ionnaires w ere used by 40.7% of respondent s; 54.5% used general abilit y t est s; 60.1% used t est s of specif ic skills and 44.6% lit eracy/numeracy t est s.

EM PLO Y M EN T,

2

I N

The Report s are available at t he w ebsit es of t he Nuff ield Council on Bioet hics and t he Human Genet ics Commission, ht t p://w w w.nuff ieldbioet hics.org/publicat ions/index.asp and ht t p://w w w.hgc.gov.uk/insideinf ormat ion/index.ht m respect ively (17 June 2002).

SELECTI O N

1

A N D

15.3 Anot her general quest ion concerns t he accuracy and predict ive capacit y of genet ic t est s. Earlier chapt ers of t his Report have indicat ed t hat our behaviour is complex, inf luenced bot h by genet ic and environment al f act ors, and by our ow n decisions. At present , accurat e and reliable t est s of t he genet ic component s of behaviour in t he normal range simply do not exist . If a screening device is not accurat e and reliable, it cannot be t he basis f or f air and eff icient decisions in relat ion t o educat ion, employment or insurance. In addit ion, if a behavioural t rait is w rongly assumed t o be immut able, t hen many personal achievement s, w hich are t he product of learning, individual init iat ive, det erminat ion and hard w ork, may be neglect ed. This is not a problem peculiar t o genet ic t est ing f or behavioural t rait s. There is considerable use of IQ and apt it ude t est s f or ent rance t o schools and universit ies. In t he cont ext of employment , int erview ing is by f ar t he most commonly used t echnique f or t he recruit ment f or managerial, prof essional and skilled manual jobs. How ever, a recent survey by t he Chart ered Inst it ut e f or Personnel and Development (CIPD) revealed t hat quest ionnaires t o evaluat e personalit y t rait s are increasingly used.2 These met hods prof ess t o assess cognit ive abilit y, personalit y, propensit y f or dishonest y or ot her deviant behaviour and t rait s such as anger, aggression, anxiet y, obsession and low self -est eem. There is much scept icism about t he predict ive validit y of t hese t est s.3 The major risk is t hat of w rongly at t ribut ing t o t he individual t he charact erist ics of t he group. It is diff icult t o know how accurat ely t he t est w ill ident if y t hose w ho w ill act on a part icular propensit y.

TESTI N G

15.2 One series of quest ions relevant t o all t hese cont ext s is t hose relat ing t o privacy, consent and conf ident ialit y. These w ere invest igat ed in relat ion t o inherit ed disease and disabilit y in t he earlier Report of t he Nuff ield Council on Bioet hics on Genet ic Screening: Et hical Issues (1993), and in t he report of t he Human Genet ic Commission (HGC), Inside Inf ormat ion: Balancing Int erest s in t he Use of Personal Genet ic Dat a (M ay 2002). Alt hough issues regarding privacy, consent and conf ident ialit y w hich are specif ic t o behavioural genet ics are discussed in t his chapt er, t he reader is ref erred t o t hose report s f or considerat ion of t he broader aspect s.1

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15.1 As noted in Chapters 13 and 14, the selection of individuals on the basis of a genetic predisposition to behavioural traits may have potential applications in several different settings. These include the streaming of children in schools, aptitude testing for university entrance or employment, and the screening of potential or existing employees on the basis of genetic susceptibility to behavioural traits such as aggression, anxiety, novelty-seeking or sexual orientation. Insurers might also wish to make use of knowledge about genetic predispositions to certain behaviours, such as risk-taking, for some types of personal and life insurance and employer’s liability and medical insurance. These possible uses of genetic information are discussed in this chapter, following an account of some relevant general principles.

CH A PTER

Test ing and select ion in employment , educat ion and insurance

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Box 15.1: Guiding legal principles The general legal principles relevant t o policy and regulat ion of t he use of genet ic inf ormat ion can be derived in t he main f rom t hree inst rument s: ■ The Convent ion For t he Prot ect ion of Human Right s and Dignit y Of The Human Being w it h Regard To The Applicat ion of Biology and M edicine (Council of Europe, Oviedo, 4 April 1997) (‘t he Convent ion’) ■ The Universal Declarat ion on t he Human Genome and Human Right s (UNESCO, 11 November 1997) (‘t he Declarat ion’) ■ Chart er of Fundament al Right s of t he European Union (EU, Nice, 7 December 2000) (‘t he Chart er’). The relevant provisions of t hese inst rument s may be summarised as f ollow s: The Convent ion The Convent ion expressly prohibit s any f orm of discriminat ion on grounds of genet ic herit age. Furt her, it provides t hat t est s w hich are predict ive of genet ic diseases or w hich serve t o ident if y a person as a carrier of a gene responsible f or disease or t o det ect a genet ic predisposit ion or suscept ibilit y t o a disease may be perf ormed only f or healt h purposes* or f or scient if ic research linked t o healt h purposes and subject t o appropriat e genet ic counselling. Int ervent ions on t he human genome are prohibit ed unless undert aken f or prevent ive, diagnost ic or t herapeut ic purposes and only if t he aim is not t o int roduce any modif icat ion t o t he genome of any descendant s. The Convent ion has not yet been rat if ied by t he UK and has no legal f orce in t his count ry. The Declarat ion The Declarat ion provides t hat everyone has t he right t o respect f or t heir dignit y and t heir right s regardless of t heir genet ic charact erist ics and t hat such dignit y ‘makes it imperat ive not t o reduce individuals t o t heir genet ic charact erist ics and t o respect t heir uniqueness and diversit y’ (Art icle 3). Research, t reat ment and diagnosis aff ect ing an individual’s genome shall only be undert aken af t er rigorous and prior assessment of t he risks and benef it s pert aining t heret o. Like t he Convent ion, t he Declarat ion includes an express prohibit ion on discriminat ion based on genet ic charact erist ics t hat is int ended t o or has t he eff ect of inf ringing human right s. Genet ic dat a must be held in condit ions of conf idence, and no research or applicat ions of research concerning t he human genome (in part icular in t he f ields of biology, genet ics and medicine) should prevail over respect of human right s and t he dignit y of individuals. The Declarat ion has no legal f orce and is int ended only as a st at ement of principles w hich st at es are asked t o promot e. The Chart er In common w it h t he Convent ion and t he Declarat ion, t he Chart er cont ains an express and f ree-st anding provision w hich prohibit s any discriminat ion based on genet ic f eat ures. As part of t he right t o respect f or physical and ment al int egrit y, Art icle 2 provides t hat , in t he f ields of medicine and biology, part icular respect must be given t o prohibit ion of eugenic pract ices,† in part icular t hose aimed at t he select ion of persons. The UK, as a M ember of t he European

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

CH A PTER

Union, is a part y t o t he Chart er. The Chart er is a non-binding inst rument w hich is likely t o have only indirect legal f orce t hrough resort t o it by t he European Court of Just ice as a source of legal principle.

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It is t o be not ed t hat t he European Group on Et hics in Science and New Technologies, w hen report ing on t he draf t Chart er insist ed (by a majorit y) t hat a specif ic addit ional provision dealing w it h eugenic pract ices be included. The minorit y considered t hat t here w as a diff icult y in def ining eugenics and t he group as a w hole recognised t hat cert ain current pract ices might be properly t ermed as eugenics. The majorit y, how ever, insist ed on inclusion of a specif ic prohibit ion because ot herw ise ‘t he Chart er w ould be missing t he point if it did not ref er t o one of t he main challenges of human genet ics.’ See European Group on Et hics in Science and New Technologies. Cit izens Right s and New Technologies: A European Challenge (Brussels, 23 M ay, 2000). ht t p://w w w.europarl.eu.int /chart er/civil/pdf /con233_en.pdf (18 Jul 2002).

15.4 In t his sect ion w e set out how t he law current ly deals w it h t he use of genet ic inf ormat ion in t he cont ext of employment . It is import ant t o not e t hat , t o dat e, most discussion in t his area has f ocused on clinical disorders. The pot ent ial use of genet ic inf ormat ion t hat concerns behavioural t rait s in t he normal range of variat ion has not been w idely considered.

A N D I N SU RA N CE

4

ED U CATI O N

15.5 At present t here is no legislat ion in t he UK t hat direct ly regulat es genet ic t est ing or t he use of genet ic inf ormat ion in employment . At common law, an employer may law f ully require an applicant t o undert ake genet ic t est ing in order t o be appoint ed t o a part icular job. Whet her an exist ing employee can be required t o submit t o a genet ic t est depends on t he express or implied t erms of t he individual’s cont ract of employment . Employers have no general pow er t o require employees t o submit t o medical examinat ion (t his w ould include a genet ic t est ). How ever, it may be implied t hat t he employee could be required t o do so if t he employer had reasonable grounds f or believing t hat t he employee might be suff ering f rom a ment al or physical disabilit y likely t o cause harm t o t he employee or t o ot her people. This is an aspect of t he so-called dut y of mut ual t rust and conf idence bet w een employer and employee, w hich is an obligat ion of uncert ain scope t hat depends upon judicial int erpret at ion.4 Similarly, at common law t he right t o use genet ic inf ormat ion about an employee depends upon t he express or implied t erms of t he employment cont ract . In some circumst ances, discriminat ion law, t he law on unf air dismissal and t he developing law of privacy and conf ident ialit y f or employees might give rise t o right s f or jobseekers and employees (see paragraphs 15.11 – 15.15).

EM PLO Y M EN T,

The current legal framew ork

I N

Employment

SELECTI O N

†

A N D

The Explanat ory Report t o t he Convent ion (paragraphs 84 t o 86) makes clear t hat genet ic t est ing f or employment or insurance purposes or ot her commercial purposes f alls out side t he legit imat e t est ing f or healt h care purposes, and is a disproport ionat e int erf erence w it h t he right s of t he individual t o privacy. Paragraph 86 provides: ‘An insurance company w ill not be ent it led t o t he holding of a predict ive genet ic t est . Nor w ill it be able t o ref use t he conclusion of modif icat ion of such a policy on t he ground t hat t he applicant has not submit t ed t o a t est as t he conclusion of a policy cannot reasonably be made condit ional on t he perf ormance of an illegal act ’. The Convent ion does, how ever, provide (in Art icle 26) t hat t he rest rict ion on predict ive genet ic t est s may be overridden w here prescribed by law and necessary in a democrat ic societ y in t he int erest of public saf et y, f or t he prevent ion of crime, f or t he prot ect ion of public healt h or f or t he prot ect ion of t he right s and f reedoms of ot hers.

TESTI N G

*

See, f or example, Bliss v Sout h East Thames Regional Healt h Aut horit y. (1985). Indust rial Relat ions Law Report s 308. The Court of Appeal f ound t hat a medical examinat ion had been imposed w it hout reasonable cause because w hat t he employer did (according t o Lord Just ice Dillon) w as ‘by any object ive st andard out rageous’.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

15.6 By cont rast , about half t he st at es in t he US have enact ed law s prohibit ing genet ic discriminat ion in employment . President Clint on signed a similar Execut ive Order applicable t o f ederal employees, excluding t he Armed Forces, on 8 February 2000. The main reasons f or t his legislat ion in t he US are, f irst , t hat employers responsible f or t he medical cost s of employees and t heir dependant s have a st rong incent ive t o exclude t hose genet ically predisposed t o cert ain illnesses and, secondly, t hat individuals w ho are at a genet ic risk of illness may be discouraged f rom t aking genet ic t est s if t hey believe t hat t heir employers w ill have access t o t his inf ormat ion. Bot h of t hese reasons are signif icant in t he US because of t he employer’s role in f inancing healt h care. The exist ence of t he Nat ional Healt h Service (NHS) means t hat t hese mot ivat ions are of less signif icance in t he UK.

Discrimination law s 15.7 In bot h t he US and t he EU, genet ic screening and t he pract ice of using genet ic inf ormat ion may run f oul of employment discriminat ion law s, if t he t est or pract ice has a disproport ionat ely adverse impact on a prot ect ed class such as w omen or et hnic minorit ies w hich cannot be object ively just if ied f or reasons ot her t han t he gender, race and so on of t he aff ect ed group. In t he landmark case of Griggs v Duke Pow er Co.,5 t he US Supreme Court held t hat under Tit le VII of t he Civil Right s Act , f acially neut ral st andardised t est s and high school graduat ion requirement s had a disparat e impact on black applicant s and employees, and accordingly, t he employer had t o prove t hat t he qualif icat ion requirement s w ere job-relat ed and consist ent w it h business necessit y.6 Genet ic t est ing w ould off end Tit le VII only if t he eff ect of t he t est w ere t o discriminat e on t he basis of race, colour, religion, sex or nat ional origin. So f ar as is know n, Tit le VII has not yet been invoked in respect of genet ic t est ing. This may be due t o t he availabilit y of t he Americans w it h Disabilit ies Act 1990 (ADA) w hich can be used t o challenge mandat ory medical examinat ions t hat are not relat ed t o employment . How ever, even t his is of limit ed signif icance because a genet ic t est t hat revealed t he suscept ibilit y of an employee t o st ress or ot her t rait s in cert ain w orking environment s w ould be job-relat ed and hence law f ul.7 15.8 In t he EU, a similar approach is t aken t o t hat in t he US, under Art icle 141 (ex 119) of t he European Communit y (EC) Treat y and t he Equal Treat ment Direct ive 76/207/EEC, in respect of w hat is t ermed ‘indirect ’ sex discriminat ion. UK law has recent ly been amended, in line w it h t he Burden of Proof Direct ive 97/80/EC, t o def ine indirect sex discriminat ion as exist ing w here ‘an apparent ly neut ral provision, crit erion or pract ice disadvant ages a subst ant ially higher proport ion of t he members of one sex unless t hat provision crit erion or pract ice is appropriat e and necessary and can be just if ied by object ive f act ors unrelat ed t o sex.’ For example, a f act or w hich f avours spat ial abilit y may t end t o be biased against w omen and t he use of t his crit erion w ill have t o be object ively just if ied. The Race Relat ions Act 1976, in sect ion 1(1)(b), cont ains a slight ly diff erent ly w orded def init ion but t he eff ect is also t o make unlaw f ul a requirement or condit ion w hich has an unjust if iable adverse impact on a part icular racial group. On 29 June 2000, t he EC adopt ed a direct ive on discriminat ion on grounds of race or et hnic origin, w hich must be implement ed by t he

1 7 8

5

Griggs v Duke Pow er Co. (1971). 401 US 424 .

6

A t est is f acially neut ral if it does not appear t o be discriminat ory. As illust rat ed, f acially neut ral pract ices may be f ound in violat ion of law if t hey result in signif icant diff erences in t he dist ribut ion of benef it s or services t o persons based on race, nat ional origin, sex or disabilit y w it hout a subst ant ial legit imat e just if icat ion, or, if t here are equally or comparably eff ect ive alt ernat ive pract ices available t hat meet t he same goals w it h less disparat e impact .

7

Rot hst ein, M . A. (2000). Genet ics and t he w ork f orce of t he next hundred years. Colum. Bus. L. Rev. 2000, 371–401. See p. 388.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

A N D SELECTI O N I N EM PLO Y M EN T, ED U CATI O N A N D I N SU RA N CE

8

TESTI N G

15.10 The Disabilit y Discriminat ion Act 1995 (DDA) in t he UK aims t o prot ect disabled persons f rom discriminat ion. A disabilit y is def ined as ‘a physical or ment al impairment w hich has a subst ant ial and long-t erm adverse eff ect on a person’s abilit y t o carry out normal day t o day act ivit ies.’ ‘Impairment ’ is not def ined but Regulat ions provide t hat addict ion t o alcohol, nicot ine or any ot her subst ance is t o be t reat ed as not amount ing t o an impairment f or purposes of t he Act .9 Similarly, t he f ollow ing condit ions do not amount t o impairment s: a t endency t o set f ires, a t endency t o st eal, a t endency t o physical or sexual abuse of ot her persons, exhibit ionism and voyeurism. Alt hough ment al illness is covered by t he Act , t he illness must be ‘clinically w ell-recognised’.10 M oreover, a person is disabled only if t heir ‘abilit y t o carry out normal day-t o-day act ivit ies is impaired’ and t he impairment must have a ‘subst ant ial and long-t erm adverse eff ect ’ on t he abilit y t o carry out t hose act ivit ies.11 While some ‘progressive condit ions’ are covered, t his does not include t hose w ho merely have a genet ic or ot her predisposit ion t o (or risk of ) a progressive condit ion in t he f ut ure. In t he US, on t he ot her hand, t he Equal Employment Opport unit y Commission has issued an int erpret at ion of t he ADA t hat an employer w ho discriminat es against an individual on t he basis of t he result s of a predict ive genet ic t est w ould be ‘regarding’ t he individual as having a disabilit y and so violat ing t he ADA. The view of at least one leading legal expert is t hat t his int erpret at ion w ill not w it hst and judicial scrut iny.12 In any event , t he UK legislat ion does not at present include t hose w ho are simply ‘regarded’ as having a disabilit y. The DDA, t heref ore, at present has lit t le relevance t o genet ic predisposit ion t o behavioural t rait s in t he normal range.

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15.9 Alt hough t hese prohibit ions in indirect discriminat ion do provide a pot ent ial barrier t o t he use of genet ic t est ing and inf ormat ion, t heir limit at ions are obvious. The employer can just if y it s act ions on t he grounds t hat t he specif ic t est is accurat e and reliable and t hat t he use of t he inf ormat ion is ‘appropriat e and necessary’ t o t he requirement s of t he job. Ef f ect ively, discriminat ion law leaves t he cont rol of genet ic t est ing in t he employer’s hands and is not primarily concerned w it h it s ef f ect on t he dignit y or aut onomy of t he employee.

CH A PTER

UK by 19 July 2003. This def ines ‘indirect discriminat ion’ as occurring w here a provision, crit erion or pract ice ‘put s persons of a racial or et hnic origin at a part icular disadvant age’ w it hout object ive just if icat ion. On 28 November 2000, t he EC adopt ed Direct ive 2000/78/EC f or combat ing direct and indirect discriminat ion in employment on t he grounds of religion or belief , disabilit y, age or sexual orient at ion.8 This cont ains a def init ion of indirect discriminat ion similar t o t hat in t he UK Race Relat ions Act . The provisions in t he EC Direct ive on sexual orient at ion must be implement ed by t he UK by 2 December 2003. They w ill eff ect ively prevent t he use of genet ic inf ormat ion relat ing t o sexual orient at ion in t he f ield of employment . Those relat ing t o disabilit y must be implement ed by 2 December 2006, but are unlikely t o involve any signif icant change in exist ing UK law.

The Sex Discriminat ion Act and t he EC Equal Treat ment Direct ive do not apply t o discriminat ion on grounds of sexual orient at ion: Secret ary of St at e f or Def ence v M acDonald. (2001). Indust rial Relat ions Law Report s 431.

9

Disabilit y Discriminat ion (M eaning of Disabilit y) Regulat ions. (1996). SI 1996 No.1455.

10

Disabilit y Discriminat ion Act . (1995). Schedule 1, paragraph 1(1).

11

Disabilit y Discriminat ion Act . (1995). Schedule 1, paragraph 1(1).

12

Rot hst ein, M . A. (2000). Genet ics and t he w ork f orce of t he next hundred years. Colum. Bus. L. Rev. 2000, 371–401. See p. 388.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Unfair dismissal 15.11 An employee w ho is already w orking f or an employer may have a remedy under t he Employment Right s Act 1996 (ERA).13 The w eakness of t his prot ect ion, f rom t he employee’s view point , is t hat in det ermining t his quest ion, t he t ribunals give employers a broad margin of discret ion (t he so-called ‘band of reasonable responses’) in deciding w het her or not t o dismiss t he employee. An employer w ould, how ever, be bound t o f ollow a f air procedure, including a reasonable invest igat ion and an opport unit y f or t he employee t o cont est t he f act s or show w hy he or she should not be dismissed.

Privacy and confidentiality 15.12 Art icle 8 of t he European Convent ion on Human Right s and Fundament al Freedoms (ECHR) provides t hat everyone has t he right t o respect f or t heir ‘privat e or f amily lif e’. The ECHR w as incorporat ed int o domest ic law by t he Human Right s Act 1998 (HRA), giving individuals t he right t o claim compensat ion against public aut horit ies (including public employers) w ho violat e t his right . Court s and t ribunals are bound t o give eff ect t o t he ECHR, so t hat w hen int erpret ing t he dut y of mut ual t rust and conf idence or t he law on unf air dismissal (paragraph 15.11) t hey must have regard t o Art icle 8. 15.13 It seems likely t hat aspect s of biomet ric and genet ic t est ing and t he use of genet ic inf ormat ion about an individual f all under t he concept of ‘privat e and f amily lif e’. This can be deduced f rom t he case law of t he European Court on Human Right s w hich has aff orded a high degree of prot ect ion under Art icle 8 t o personal healt h and bodily int egrit y. The right is not , how ever, absolut e. The inf ringement may be just if ied if it is show n t o be ‘necessary in a democrat ic societ y in t he int erest s of nat ional securit y, public saf et y or t he economic w ell-being of t he count ry, f or t he prevent ion of crime or disorder, f or t he prot ect ion of healt h or morals, or f or t he prot ect ion of t he right s and f reedoms of ot hers.’ 14 In t he employment f ield, it is likely t hat court s and t ribunals w ill require t he employer t o show bot h t hat t he use of genet ic inf ormat ion w as necessary in relat ion t o a specif ic job, and t hat it s use w as proport ionat e t o a legit imat e aim such as prot ect ing t he healt h and saf et y of ot hers. It seems t hat a cont ract ual rest rict ion on t he right t o privacy w ill also have t o pass t his st rict t est of just if iabilit y. 15.14 Anot her possible f orm of prot ect ion f or genet ic inf ormat ion is t he common law on breach of conf idence. An obligat ion of conf idence arises in an employment relat ionship, but it is by no means clear w hat kinds of personal inf ormat ion w ould be prot ect ed since nearly all t he decided cases involve breach of commercial conf idences. Accordingly, t he Dat a Prot ect ion Act 1998 (DPA) is much more signif icant t han t he common law. Under t he DPA ‘sensit ive personal dat a’ is given special prot ect ion. This includes personal dat a of a person’s ‘physical or ment al healt h or condit ion’. M ost genet ic inf ormat ion w ould appear t o f all under t his prot ect ion, as w ould genet ic inf ormat ion about a person’s ‘sexual lif e’.

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13

For example, an employee w ho is dismissed f or ref using t o submit t o a genet ic t est or f or not allow ing t he use of genet ic inf ormat ion, w here t his is not provided f or in t he cont ract of employment and amount s t o a breach of t he dut y of mut ual t rust and conf idence may complain t hat t he dismissal is unf air. Even short of act ual dismissal, t here may be a ‘const ruct ive’ dismissal ent it ling t he employee t o resign and claim compensat ion. The employer w ill have t o show t hat it genuinely believed t hat t he dismissal relat ed t o t he employee’s ‘capabilit y’ or ‘conduct ’ or ‘some ot her subst ant ial reason’ just if ying dismissal. The employment t ribunal w ill t hen assess w het her t he dismissal is f air or unf air ‘having regard t o equit y and t he subst ant ial merit s of t he case’.

14

European Convent ion on Human Right s and Fundament al Freedoms. Art icle 8(2).

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

Nuff ield Council on Bioet hics. (1993). Genet ic Screening: Et hical Issues. Chapt er 6.

19

Human Genet ics Advisory Commission. (1999). The Implicat ions of Genet ic Test ing f or Employment , para.3.5; Trade Union Congress. (1998). Genet ic Test ing by Employers. 2nd ed., report ed t hat ‘genet ic t est ing by employers is st ill rare in t his count ry’. The Healt h and Saf et y Commission. (1996). Report of t he Working Group on Genet ic Screening and M onit oring, p.7, made a similar f inding.

I N SU RA N CE

Human Genet ics Commission. (2002). Inside Inf ormat ion: Balancing Int erest s in t he Use of Genet ic Dat a. paragraph 8.9.

18

A N D

Human Genet ics Advisory Commission. (July 1999). Implicat ions of Genet ic Test ing f or Employment .

17

ED U CATI O N

16

EM PLO Y M EN T,

The Inf ormat ion Commissioner enf orces and oversees t he Dat a Prot ect ion Act 1998 and t he Freedom of Inf ormat ion Act 2000. The Commissioner is an independent supervisory aut horit y report ing direct ly t o t he UK Parliament .

I N

15

SELECTI O N

15.18 The report of t he HGAC proposed a common set of principles f or policy, aimed at providing appropriat e prot ect ion t o t he public if and w hen genet ic t est ing f or diseases in employment becomes a real possibilit y. We consider t hat t hese principles f orm a usef ul basis f or policy-making and apply equally t o behavioural t rait s as t o diseases. They are:

A N D

15.17 The report of t he HGC concluded t hat at present t here is no evidence in t his count ry of any syst emat ic use of predict ive personal genet ic inf ormat ion in employment .17 This conf irms t he f indings of t he earlier report s of t he Nuff ield Council and t he HGAC.18,19 Indeed, since t he lat t er report s w ere published, t he only employer t hat had been know n t o use such t est s (t he M inist ry of Def ence, t o screen aircrew recruit s f or sickle cell disease) has ceased t he pract ice. The HGAC concluded t hat ‘it w ill t ake major development s bot h in our underst anding of common diseases and in genet ic t est ing it self bef ore genet ic t est ing becomes a serious issue f or employment pract ice’ and t his conclusion applies equally st rongly t o behavioural t rait s and non-clinical charact erist ics.

TESTI N G

15.16 The pot ent ial uses of personal genet ic inf ormat ion in employment have been t he subject of several earlier report s. How ever, all of t hese f ocus on inf ormat ion t hat is predict ive of inherit ed disease or inf ormat ion about part icular genet ic variat ions t hat might indicat e t hat a person is suscept ible t o a specif ic occupat ional disease or w orkplace chemical. None of t hese report s has considered t he use of personal genet ic inf ormat ion relevant t o part icular t rait s w it hin t he normal range of behaviour. Our f ocus is on w het her t he conclusions in t hose earlier report s relat ing t o inherit ed disease and occupat ional hazards are also applicable t o normal behavioural t rait s.

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Earlier reform proposals

CH A PTER

15.15 The handling of genet ic t est result s is required t o meet t he DPA’s principles of f airness and law f ulness. In part icular, t he explicit consent of t he individual is required (unless t here is a legal obligat ion t o process t he dat a). The EC Dat a Prot ect ion Direct ive 95/46/EC, on w hich t he DPA is based, specif ies t hat consent must be ‘f reely given, specif ic and inf ormed’. The UK Inf ormat ion Commissioner has given guidance int erpret ing t his as meaning t hat t here must be some act ive communicat ion bet w een t he part ies.15 An individual or organisat ion w ho uses dat a cannot inf er consent simply f rom non-response t o a communicat ion. The Inf ormat ion Commissioner has issued a draf t code of pract ice on t he use of personal dat a w it hin employer/employee relat ionships, under sect ion 53 of t he DPA. This cont ains a sect ion dealing w it h t he use of genet ic t est ing in employment w hich is based on t he recommendat ions of t he 1999 report of t he Human Genet ics Advisory Commission’s (HGAC) on Implicat ions of Genet ic Test ing f or Employment .16 The f inal version of t he Code relat ing t o medical and genet ic t est ing is due t o be published by t he end of 2002.

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

(i) An individual should not be required t o t ake a genet ic t est f or employment purposes – an individual’s ‘right not t o know ’ t heir genet ic const it ut ion ought t o be upheld. (ii) An individual should not be required t o disclose t he result s of a previous genet ic t est unless t here is clear evidence t hat t he inf ormat ion it provides is needed t o assess eit her current abilit y t o perf orm a job saf ely or suscept ibilit y t o harm f rom doing a cert ain job. (iii) Employers should off er a genet ic t est (w here available) if it is know n t hat a specif ic w orking environment or pract ice, w hile meet ing healt h and saf et y requirement s, might pose specif ic risks t o individuals w it h part icular genet ic variat ions. For cert ain jobs w here issues of public saf et y arise, an employer should be able t o ref use t o employ a person w ho ref uses t o t ake a relevant genet ic t est . (iv) Any genet ic t est used f or employment purposes must be subject t o assured levels of accuracy and reliabilit y, ref lect ing best pract ice in accordance w it h t he principles est ablished by t he Advisory Commit t ee on Genet ic Test ing: ‘[A]ny use of genet ic t est ing should be evidence-based and consensual. Result s of any t est undert aken should alw ays be communicat ed t o t he person t est ed and prof essional advice should be available. Inf ormat ion about and result ing f rom t he t aking of any t est should be t reat ed in accordance w it h Dat a Prot ect ion principles … Furt hermore, t est result s should be caref ully int erpret ed, t aking account of how t hey might be aff ect ed by w orking condit ions.’ (v) If mult iple genet ic t est s w ere t o be perf ormed simult aneously, t hen each t est should meet t he st andards set out in (ii), (iii) and (iv). 15.19 The Report of t he HGC concluded t hat genet ic t est ing is unlikely t o provide any inf ormat ion t hat cannot be gat hered by means of exist ing medical and screening procedures. Given t he current uncert aint ies about int erpret ing genet ic inf ormat ion, t he HGC considered t hat it w ould be more appropriat e t o monit or t he healt h of a person by ot her more direct means.20 It recommended a volunt ary undert aking by employers t o inf orm t he HGC of any proposals t o use genet ic t est ing f or healt h and saf et y purposes.21 The HGC also recommended t hat genet ic t est s should not be a condit ion of employment .22

Testing for behavioural traits 15.20 As already not ed, t he recommendat ions in earlier report s are concerned w it h t he occupat ional healt h and saf et y of employees and jobseekers. They apply a model of t he aut onomy of t he individual pat ient in t he medical sphere t o t he employment relat ionship. In t he case of behavioural t rait s w it hin t he normal range, w hich are t he subject of t his Report , w e are not concerned w it h pat ient s. M oreover, t he employment relat ionship is less recept ive t o t he applicat ion of t he medical model. The inherent inequalit y of bargaining posit ion and pow er bet w een t he employer and t he individual employee means t hat t he employer is likely t o init iat e t he t est s and t o decide how t hey are t o be administ ered and used. A ‘right t o ref use’ t o t ake a t est t o disclose genet ic inf ormat ion or a ‘right t o know ’

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20

Human Genet ics Commission. (2002). Inside Inf ormat ion: Balancing Int erest s in t he Use of Genet ic Dat a. paragraph 8.18.

21

Ibid. paragraph 8.19.

22

Ibid. paragraph 8.15.

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

CH A PTER

t he out come, is likely t o be of lit t le pract ical value w here t he employee has t o choose bet w een exercising t he right or w aiving it in order t o secure a livelihood. The public int erest or pat ernalist ic just if icat ions f or overriding t he individual’s w ishes w here t here is a serious danger t o t he healt h or saf et y of t he employee or t hird part ies do not exist in t he case of non-clinical behavioural t rait s.

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23

Disabilit y Right s Commission (2002). First Review of t he Disabilit y Discriminat ion Act .

24

This w ould be in accordance w it h Art icle 25 of t he EU Chart er of Fundament al Right s.

I N SU RA N CE

15.23 Some of t he t rait s t hat are st udied in behavioural genet ics are of part icular relevance t o educat ion. The most obvious link is w it h int elligence, but research int o t rait s such as ant isocial behaviour may also have implicat ions f or t he educat ion syst em. Educat ionalist s have already developed a range of t est s w it h w hich children can be assessed, such as

A N D

Education

ED U CATI O N

15.22 There is a quest ion w het her t he Disabilit y Discriminat ion Act (DDA) should be ext ended t o cover (i) genet ic predisposit ions in general, and (ii) non-clinical behavioural t rait s in part icular. On t he f irst quest ion, t he Disabilit y Right s Commission (DRC) has recommended t hat t he DDA should be ext ended t o people w ho have a genet ic predisposit ion and t hat legislat ion should prohibit employers f rom view ing t he result s of genet ic t est s save in very limit ed circumst ances.23 The DRC has not dealt specif ically w it h t he second quest ion. In our view, t here is a danger t hat singling out genet ic predisposit ions t o behavioural t rait s w it hin t he normal range f or special t reat ment or labelling t hem as ‘disabilit ies’ w ill aggravat e t he st igma at t ached t o cert ain behavioural t rait s. This danger might be overcome by including discriminat ion on grounds of ‘genet ic f eat ures’ in a single general st at ut e covering all f orms of unlaw f ul discriminat ion.24 Such legislat ion should specif ically cover asympt omat ic employees.

EM PLO Y M EN T,

■ Any inquiry int o t he pot ent ial use of genet ic t est ing of behavioural t rait s in t he w orkplace should include an invest igat ion of t he use of ot her purport edly predict ive scient if ic m et hods, such as psychom et ric t est s, f or sim ilar purposes.

I N

■ Em ployers should not dem and t hat an individual t ake a genet ic t est f or a behavioural t rait as a condit ion of em ploym ent . The proper approach w ould be t o m onit or em ployees f or early w arning signs of behaviour (such as violence) t hat w ould m ake t hem incapable of perf orm ing t he job sat isf act orily.

SELECTI O N

■ Em ployees should be select ed and prom ot ed on t he basis of t heir abilit y t o m eet t he requirem ent s of t he job, and t hey should be m onit ored t o ensure t hat t heir perf orm ance m eet s t hose requirem ent s.

A N D

■ The prim ary dut y of em ployers is t o provide a saf e environm ent f or t heir em ployees and ot hers. The aim should be t o rem ove hazards f rom t he w orkplace, not t o rem ove em ployees on t he basis of inherit ed charact erist ics or suscept ibilit y t o part icular f orm s of behaviour w it hin t he norm al range.

TESTI N G

15.21 This leads us t o t he f ollow ing conclusions and recommendat ions in t he cont ext of t he use by employers of genet ic t est ing f or behavioural t rait s:

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

reading abilit y, verbal abilit y, IQ scores and so on. The classif icat ion of children based on such skills and t he provision of part icular t ypes of educat ional programme accordingly is also an est ablished part of our educat ional syst em. It is not clear how f indings in behavioural genet ics and t he pot ent ial development of genet ic t est s might or should impinge upon current pract ices. Some researchers in behavioural genet ics have highlight ed t he pot ent ial import ance of t he research in inf orming pract ices in educat ion but as yet t he issue has not received subst ant ial at t ent ion.25 15.24 The development of t est s t hat provide inf ormat ion about genet ic inf luences on t rait s such as int elligence and ant isocial behaviour w ould raise a number of quest ions: ■ Should genet ic t est s be used t o ident if y children w ho may be suscept ible t o t rait s t hat could aff ect t heir ow n educat ional achievement , such as low er t han average IQ? ■ Should genet ic inf ormat ion be used t o det ermine w hich t ype of educat ional programme a part icular child, or group of children, receives? ■ Should genet ic t est s be used t o ident if y children w ho may be suscept ible t o t rait s t hat could aff ect t he educat ional achievement and w ellbeing of ot her children, f or example ant isocial behaviour? 15.25 The use of such t est s in t he educat ional cont ext may lead t o st igmat isat ion or a t endency t ow ards ‘genet ic self -f ulf illing prophecies’ t hat const rain a child’s self -image. We not ed in paragraphs 14.41 – 14.43 t hat carrying out a genet ic t est on a child unable t o consent t o t he procedure w ould have t o be in t he best int erest s of t he child. It may be argued t hat in relat ion t o educat ion, t he predict ive use of genet ic inf ormat ion could be just if ied, if t he aim of such an approach w as t o provide bet t er and more appropriat e schooling f or children. Whet her genet ic inf ormat ion could be used in t his w ay t o posit ive eff ect is current ly unclear. It may be t hat , w hen used in conjunct ion w it h ot her inf ormat ion about children, including evidence f rom previous educat ional perf ormance, such inf ormat ion could play a usef ul role. How ever, w ider argument s about t he advant ages and disadvant ages of t ailoring educat ional programmes t o groups of children, in w hat ever w ay such groups are def ined, w ill also be relevant . 15.26 We not e, w it h some concern, t hat t he implicat ions f or educat ion of research in behavioural genet ics have not yet received signif icant crit ical at t ent ion. In t he light of t he issues t hat m ay arise if genet ic inf orm at ion about behavioural t rait s is applied in t he cont ext of educat ion, w e recom m end t hat f urt her invest igat ion of t he w ays in w hich such research m ight be applied, and t he result ing et hical and social issues, be undert aken. We recom m end t hat dialogue bet w een t hose involved in educat ion and researchers in behavioural genet ics be prom ot ed. We recom m end, f urt her, t hat unt il such dialogue and research is undert aken, genet ic inf orm at ion about behavioural t rait s in t he norm al range should not be used in t he cont ext of t he provision of educat ion.

25

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For example, see suggest ions made regarding t he const ruct ive use of genet ic inf ormat ion in educat ion by Prof essor Robert Plomin in t he f ollow ing art icle: Genius of genes. 8 August 2000. ht t p://new s.bbc.co.uk/1/hi/sci/t ech/850358.st m (20 August 2002).

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

The ABI comprises over 400 insurance companies w hich bet w een t hem account f or over 96% of t he business of insurance companies in Brit ain.

29

Associat ion of Brit ish Insurers. (December 1997 and revised August 1999). Genet ic Test ing: ABI Code of Pract ice. The principal f eat ure of t his code is t hat applicant s f or insurance may not be asked t o undert ake a genet ic t est t o obt ain insurance and only t est s approved by, or current ly under considerat ion by, t he GAIC may be t aken int o account . People w it h negat ive t est result s may benef it w here t he t est result count eract s a f amily hist ory of a condit ion.

30

Bot h t he House of Commons Select Commit t ee and t he HGAC have been crit ical of t he syst em of self -regulat ion, and part icularly t he lack of unif ormit y of applicat ion of t he Code of Pract ice amongst insurance companies. The House of Commons Select Commit t ee not ed in part icular as one of it s conclusions (paragraph 23) t hat ‘There must be doubt s w het her t he ABI, a t rade organisat ion f unded by insurers t o represent t heir ow n int erest s, is t he right body t o regulat e t he use of genet ic t est result s’.

31

A Genet ic Test is def ined as ‘an examinat ion of t he chromosome, DNA or RNA t o f ind out if t here is an ot herw ise undet ect able disease relat ed genot ype, w hich may indicat e an increased chance of developing a specif ic disease in t he f ut ure’.

32

Associat ion of Brit ish Insurers. (August 2001). ABI Response t o Public Consult at ion, paragraph 2.2.

I N SU RA N CE

28

A N D

Human Genet ics Commission. (M ay 2001). The Use of Genet ic Inf ormat ion in Insurance: Int erim Recommendat ions of t he Human Genet ics Commission.

ED U CATI O N

27

EM PLO Y M EN T,

Nuff ield Council on Bioet hics. (1993). Genet ic screening: et hical issues; Human Genet ics Advisory Commission. (December 1997). The Implicat ions of Genet ic Test ing f or Insurance; House of Commons Select Commit t ee on Science and Technology. (April 2001). Genet ics and Insurance, Fif t h Report ; Human Genet ics Commission. (M ay 2001). The Use of Genet ic Inf ormat ion in Insurance: Int erim Recommendat ions of t he Human Genet ics Commission. The HGC convened various meet ings t o discuss insurance and genet ics and t he relevant minut es are collect ed at ht t p://w w w.hgc.gov.uk/t opics.ht m#ins (19 July 2002).

I N

26

SELECTI O N

15.30 If research in behavioural genet ics w ere t o provide such evidence, t here are clearly import ant social and regulat ory issues w hich arise. The ABI has assert ed t hat t he suggest ion t hat genet ic inf ormat ion indicat ing suscept ibilit y t o part icular t ypes of behaviour (such as aggression or novelt y-seeking) w ould be used displays a misunderst anding of t he manner

A N D

15.29 The exist ing debat e has not addressed t he regulat ory issues w hich arise f rom t he possibilit y of using genet ic inf ormat ion about behaviour. Indeed, t he ABI Code of Pract ice it self def ines a ‘Genet ic Test ’ in a manner w hich is limit ed t o t est s w hich indicat e t he risk of a disease developing in t he f ut ure.31 This is principally because, as t he ABI has st at ed, ‘behavioural genet ics is unlikely t o be of relevance t o insurers, because [t he ABI] cannot see t hat it w ould be possible t o robust ly demonst rat e a clear link bet w een genet ic inf ormat ion regarding suscept ibilit ies t o part icular behavioural t rait s and a change in t he risk of an individual claiming on an insurance policy’.32

TESTI N G

15.28 In t he lat e 1990s, most Brit ish insurance indust ry, act ing t hrough t he Associat ion of Brit ish Insurers (ABI)28 agreed on a self -regulat ory Code of Pract ice29 on use of genet ic t est s in insurance.30 In April 1999, t he UK Government est ablished t he Genet ics and Insurance Commit t ee (GAIC) t o evaluat e genet ic t est s, t o recommend t o insurers and t he Government w het her part icular t est s are appropriat e f or use by insurers and t o oversee t he use of genet ic t est s by insurers. In 2001, a morat orium, w hich exceeds in lengt h and f inancial limit s t hat recommended by t he HGC, w as announced by t he insurance indust ry on t he use of DNA t est result s in insurance. This remains a volunt ary agreement and t he Government has not yet considered it necessary t o make any legislat ive int ervent ions in t his area.

1 5

15.27 The implicat ions of t he use of genet ic inf ormat ion by insurers have been considered in det ail by various bodies in recent years.26 M any concerns have been raised, including t he risk of basing decisions on unreliable t est s and t he possibilit y of excluding vulnerable groups f rom obt aining insurance. The Nuff ield Council on Bioet hics recommended a morat orium on t he use of genet ic inf ormat ion by insurers in most sit uat ions in 1993, and many ot her groups subsequent ly endorsed t his suggest ion, most recent ly t he HGC.27

CH A PTER

Insurance

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

in w hich t he risk prof ile of an individual is est ablished.33 How ever, in it s response t o t he Working Part y’s consult at ion w it h t he public, t he Genet ics Group of t he Facult y and Inst it ut e of Act uaries observed t hat w hile ‘at t his st age, no-one know s w het her inf ormat ion on behavioural t rait s w hich is usef ul f or predict ing abnormal levels of insurance risk w ill ever be obt ained f rom Genet ic Test s … it cannot be ruled out . Furt her, t he dist inct ion bet w een behavioural and medical condit ions could w ell be blurred.’ When one considers t he manner in w hich inf ormat ion as t o past behaviour is current ly required by insurers in proposals f or policies and t hen used as an act uarial predict or of f ut ure risks, t he view of t he ABI seems less convincing t han t hat of t he Facult y and Inst it ut e of Act uaries. This mat t er is considered f urt her in paragraph 15.33. 15.31 There are various t ypes of relevant insurance in t his cont ext : lif e insurance, crit ical illness insurance, income prot ect ion and medical insurance. As not ed by t he Consumers’ Associat ion, w it h t he cont ract ion of t he w elf are st at e and prominence being given by bot h major polit ical part ies t o privat e sect or provision, insurance-based and insurance-relat ed product s and services are likely t o play an increasing role in t he lives of cit izens.34 Societ y is moving t ow ards a posit ion w here access t o insurance can no longer be seen as a mere commercial decision by an individual t o purchase an ext ra benef it w hich he or she w ill enjoy in addit ion t o a guarant eed saf et y-net of st at e provision. This change in t he role of insurance st rongly suggest s t hat access t o insurance should more properly be view ed in t erms of an essent ial social right rat her t han an opt ion f or t he f ew w it h appropriat e f inancial resources. This change requires one t o ensure t hat unreasonable discriminat ion on t he basis of genet ic inf ormat ion as t o behaviour is prevent ed by st rict regulat ion. Wit hout such regulat ion, t here is a real risk t hat scient if ic development s in t he f ut ure w ill lead t o t he creat ion of a group of individuals w hose genet ic charact erist ics make t hem eit her uninsurable in t he commercial judgement of t he insurance indust ry, or insurable only at a level of prohibit ively high premiums. The HGC has emphasised t he w ider moral and social consequences of allow ing use of genet ic inf ormat ion (albeit in t he cont ext of disease predict ion) in decision-making in insurance.35 We concur w it h t he HGC t hat w here insurance is linked t o import ant public goods such as house ow nership or lif e insurance and persons are rest rict ed f rom obt aining t hese goods because of personal genet ic qualit ies, it is not unreasonable t o balance t he cost s t o t hese individuals and t o societ y against t he cost s t o t he insurance indust ry. 15.32 Against t his one must , how ever, balance anot her aspect of t he public int erest , namely t he need t o ensure t hat t he cost of obt aining insurance is not rendered prohibit ive t o societ y as a w hole because premiums are calculat ed w it hout access t o import ant predict ive genet ic inf ormat ion w hich w ould allow t hose w it hout genet ic predisposit ions t o cert ain behaviour t o benef it f rom low er premiums. An argument can be made t hat t he great er t ransparency provided by accurat e genet ic inf ormat ion in assessing individual risk w ill be of benef it in set t ing appropriat e premiums f or part icular individuals. In addit ion, t he insurance indust ry cont ends t hat t he problem of so-called ‘adverse select ion’ might arise if t here w ere a prohibit ion on use of genet ic t est s. ‘Adverse select ion’ can occur if applicant s f or insurance need not disclose relevant risk f act ors and consequent ly individuals at high-risk apply more

33

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Associat ion of Brit ish Insurers. (August 2001). ABI Response t o Public Consult at ion, paragraph 2.3.

34

Consumers’ Associat ion, Consumer Brief ing, Genet ics and Insurance: Unravelling t he Code f or Consumers.

35

Human Genet ics Commission. The use of genet ic inf ormat ion in insurance: Int erim recommendat ions of t he Human Genet ics Commission. 1 M ay 2002. ht t p://w w w.hgc.gov.uk/business_publicat ions_st at ement _01may.ht m (20 August 2002).

Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

I N EM PLO Y M EN T, ED U CATI O N A N D I N SU RA N CE

36

SELECTI O N

15.36 Given t hat even in t he case of predict ing genet ic diseases, scient if ic development s have not yet caused t he UK Government t o int ervene w it h a syst em of regulat ion f or t he insurance indust ry, it is premat ure t o arrive at any conclusions on t he use of genet ic inf ormat ion

A N D

15.35 From a purely commercial perspect ive, one could view such inf ormat ion as being merely anot her f act w hich an insurer should be permit t ed t o act upon in making a commercial decision as t o w het her he w ill cont ract w it h a person and t he t erms upon w hich he w ill cont ract . As observed above, t here is a cogent case t o be made f or permit t ing t he use of such inf ormat ion in t he public int erest . How ever, w hen one considers t he f act t hat a genet ic predisposit ion t o cert ain pat t erns of behaviour is not a mat t er w it hin one’s cont rol, and t hat use of such inf ormat ion could lead t o denial of access t o an essent ial social benef it (t he abilit y t o cont ract f or insurance), t he right of t he insurer t o demand and use a t est is much less clear. It could be said against t his t hat using such inf ormat ion regarding suscept ibilit y t o cert ain f ut ure behaviour pat t erns is no diff erent f rom t he current use of f amily hist ory of illness by insurers in det ermining access t o, f or example, lif e insurance and crit ical illness policies and in t he set t ing of premiums.36 This presupposes t hat t he use of f amily hist ory, an equally unchangeable f act about an individual, is a legit imat e f act or in decisions about t he provision of insurance. It can be argued t hat if one view s access t o insurance as being a social right , f amily hist ory should not be permit t ed t o w eigh against an applicant f or insurance.

TESTI N G

15.34 The essent ial issue f or regulat ion and policy is w het her, if such inf ormat ion can in f ut ure be obt ained, an insurance company should be able t o demand an appropriat e t est and use t he result s, and t o ref use t o off er insurance t o t hose w ho ref use t o t ake t he t est or off er higher premiums. This is a diff icult quest ion and t he answ er depends on t he social and et hical perspect ive f rom w hich it is approached.

1 5

15.33 Alt hough science has not yet developed t o a st age w here genet ic inf ormat ion can be used t o indicat e suscept ibilit y t o specif ic behavioural pat t erns, it is not diff icult t o f oresee how insurers could use such inf ormat ion in t he f ut ure t o decide w hich individuals w ill be off ered insurance, and on w hich t erms. This is because t he decision t o underw rit e and t he t erms of insurance are based essent ially on personal inf ormat ion concerning a proposed person. In t he example of driving insurance, t his w ill include dat a such as age, sex, occupat ion, past driving record and so on. Such inf ormat ion det ermines premiums. If one w ere able t o classif y a person as being more likely t han ot hers t o be aggressive or exhibit novelt yseeking behaviour using genet ic t est s, t his is just a f urt her layer of inf ormat ion w hich an insurance company could use t o inf orm it s decisions. Just as an individual’s past record of driving is an indicat or of t he likelihood of f ut ure accident s, it could be said t hat an aggressive personalit y equally bears on t he f ut ure risks of an accident . Conversely, an insurer may consider t hat a person w it h a passive personalit y is a much bet t er risk t o insure.

CH A PTER

f or insurance, or persons at low -risk apply less, t hereby skew ing t he pool of individuals request ing insurance.

In t he cont ext of genet ic t est s w hich predict disease, t his very argument appears t o have already been deployed by t he insurers: see M inut es of Plenary M eet ing of HGC, 2 M arch 2001, paragraph 5.5 w here t he consult at ion responses t o Whose Hands on Your Genes? w ere considered (w w w.hgc.gov.uk/business_meet ings_02march.ht m). The HGC has expressed part icular concern t hat t he exist ing use of f amily hist ory, especially w here t his clearly has a large genet ic (inherit ed) component , should be given f urt her considerat ion (Human Genet ics Commission. (M ay 2001). The Use of Genet ic Inf ormat ion in Insurance: Int erim Recommendat ions of t he Human Genet ics Commission.)

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Gen et i cs an d h u m an b eh avi o u r : t h e et h i cal co n t ext

about behavioural t rait s in t he normal range. It is clear, how ever, t hat one cannot cont inue t o view insurance provision and t he t erms of such provision as purely commercial decisions. The commercial imperat ive of insurers is clearly t o set premiums and off er insurance based on t he best possible inf ormat ion as t o risk. Genet ic inf ormat ion may be valuable in t his regard and saf eguards as t o it s use must be developed t o ensure t hat an uninsurable group of individuals is not creat ed. 15.37 We recom m end t hat t he use of genet ic inf orm at ion about behavioural t rait s in t he norm al range should be int erpret ed as f alling under t he scope of t he f ive-year m orat orium agreed in t he UK in 2001, and should t heref ore not be used by insurance com panies in set t ing prem ium s. Fut ure discussion of possible legislat ion should include specif ic considerat ion of genet ic inf orm at ion regarding behavioural t rait s. If t he use of such inf orm at ion w ere considered, a t horough exam inat ion of t he accuracy and reliabilit y of any genet ic t est s and t heir likely predict ive pow er w ould be essent ial.

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Appendices

G e n e t i c s

a n d

h u m a n

b e h a v i o u r :

t h e

e t h i c a l

W O RKI N G

12 June 2001, London

O F

The Working Part y is very grat ef ul t o t he f ollow ing individuals f or t aking t he t ime t o meet w it h members of t he Working Part y and f or providing insight s int o issues relat ing t o research in behavioural genet ics.1

M ETH O D S

Fact-finding meetings

1 :

In November 1999, t he Council held a Workshop t hat addressed issues arising f rom t he st udy of t he genet ics of variat ion w it hin t he normal range of behavioural charact erist ics. Subsequent ly, in November 2000, t he Working Part y on Genet ics and Human Behaviour w as est ablished. The Working Part y met eleven t imes bet w een November 2000 and M ay 2002. As part of it s w ork, t he Working Part y held six f act -f inding meet ings w it h expert s in t he f ield of behavioural genet ics, philosophy and sociology in Brit ain. Three review s w ere commissioned t o assess crit ically t he current scient if ic evidence in various f ields of research in behavioural genet ics. The Working Part y also held a consult at ion w it h t he public, t he responses t o w hich are summarised in Appendix 2.

A PPEN D I X

Appendix 1: M et hods of w orking

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Prof essor Sir M ichael Rut t er, Senior Researcher, Depart ment of Social, Genet ic and Development al Psychiat ric Research, Inst it ut e of Psychiat ry, London Prof essor St even Rose, Prof essor of Biology and Direct or, Brain and Behaviour Research Group, Open Universit y and Joint Prof essor of Physic, Gresham College Dr Jonat han Flint , Wellcome Trust Senior Clinical Fellow, Wellcome Trust Cent re f or Human Genet ics, Oxf ord

4 July 2001, London Prof essor Andrew Heat h, Prof essor of Psychology in Psychiat ry and Associat e Prof essor of Genet ics, Universit y of Washingt on St Louis and Direct or, M issouri Alcohol Research Cent er, US

9 July 2001, Cambridge Prof essor Dorret Boomsma, Prof essor of Biological Psychology, Vrije Universit eit , Amst erdam, The Net herlands Prof essor John DeFries, Prof essor, Depart ment of Psychology, and Direct or, Inst it ut e f or Behavioral Genet ics, Universit y of Colorado at Boulder, US Prof essor Nick M art in, Senior Principal Research Fellow, Queensland Inst it ut e of M edical Research and Adjunct Prof essor, Depart ment of Pat hology, Universit y of Queensland, Aust ralia Associat e Prof essor Irw in D Waldman, Associat e Prof essor of Psychology, Emory Universit y, US Prof essor Thomas Bouchard, Prof essor of Psychology, Universit y of M innesot a, Direct or of t he M innesot a Cent er f or Tw in and Adopt ion Research and Principal Invest igat or on t he M innesot a Tw in Regist ry, US Prof essor Richard Rose, Prof essor of Psychology and M edical Genet ics, Indiana Universit y, US Prof essor M at t hew M cGue, Associat e Chair, and Direct or, Graduat e Program in Individual

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Inst it ut ional aff iliat ions at t he t ime of t he meet ing are list ed.

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Diff erences and Behavioural Genet ics, Depart ment of Psychology, Universit y of M innesot a and Principal Invesigat or, M innesot a Tw in Family St udy, US Prof essor Lindon Eaves, Prof essor of Psychiat ry and Dist inguished Prof essor of Human Genet ics, M edical College of Virginia, Richmond and Direct or, Virginia Inst it ut e f or Psychiat ric and Behavioral Genet ics, US

26 September 2001, London Prof essor Nick Craddock, Wellcome Trust Senior Research Fellow in Clinical Sciences and Prof essor of M olecular Psychiat ry, and Honorary Consult ant Psychiat rist , Universit y of Birmingham Prof essor Robert Plomin, Deput y Direct or, Social, Genet ic and Development al Psychiat ric Research Cent re, Inst it ut e of Psychiat ry, London

3 October 2001, London Prof essor Jonat han Glover, Direct or, Cent re of M edical Law and Et hics, King's College, London Prof essor Søren Holm, Reader in Bioet hics, Inst it ut e of M edicine Law and Bioet hics, Universit y of M anchest er Prof essor Nikolas Rose, Prof essor of Sociology, Goldsmit hs College, Universit y of London

14-16 November 2001, Washington DC, US M embers of t he Hast ings Cent er/American Associat ion f or t he Advancement of Science Group on Craf t ing Tools f or Public Conversat ion about Behavioral Genet ics: Dr V. Elving Anderson, Prof essor Emerit us, Genet ics and Cell Biology, Universit y of M innesot a, US Cat hy Baker, Plain Language Communicat ions, Bet hesda, US Prof essor Jonat han Beckw it h, American Cancer Societ y Prof essor of M icrobiology & M olecular Genet ics, Depart ment of M icrobiology & M olecular Genet ics, Harvard M edical School, US Dr Audrey Chapman, Direct or, Dialogue on Science, Et hics, and Religion, American Associat ion f or t he Advancement of Science, US Prof essor Troy Dust er, Direct or, Inst it ut e f or t he St udy of Social Change, Universit y of Calif ornia, Berkeley, US Prof essor Lee Ehrman, Dist inguished Prof essor of Biology, Division of Nat ural Sciences, Biology Program, SUNY Purchase, US Prof essor Leonard Fleck, Cent er f or Et hics & Humanit ies, M ichigan St at e Universit y, US Dr M ark Frankel, Direct or, Scient if ic Freedom, Responsibilit y and Law Program, American Associat ion f or t he Advancement of Science, US Prof essor Irving Got t esman, Sherrell J. Ast on Prof essor of Psychology, Depart ment of Psychology, Universit y of Virginia, US Prof essor Pat ricia King, Carmack Wat erhouse Prof essor of Law, M edicine, Et hics and Public Policy, The Law Cent er, Georget ow n Universit y, US Dr Yvet t e M iller, M edical Direct or, American Red Cross Great Lakes Region, US Dr Erik Parens, Direct or, The Hast ings Cent er, US Prof essor Nancy Press, Associat e Prof essor Genet ic Ant hropology, Depart ment of Public Healt h and Prevent ive M edicine, Oregan Healt h Sciences Universit y, US

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Dr Robert Wachbroit , Research Scholar, Inst it ut e f or Philosophy & Public Policy, Universit y of M aryland, US Rick Weiss, St aff Writ er, Washingt on Post , US

Review s of the evidence

Prof essor Nicholas J. M ackint osh, Depart ment of Experiment al Psychology, Universit y of Cambridge.

W O RKI N G

Chapter 7 - Intelligence

O F

The Working Part y commissioned papers f rom expert s on t hree areas of research in behavioural genet ics: research int o int elligence, personalit y t rait s and addict ion. A review of research int o ant isocial behaviour w as w rit t en by a member of t he Working Part y Prof essor Terrie M off it t , and a review of research int o sexual orient at ion w as compiled by t he Secret ariat . These papers w ere used t o inf orm t he Working Part y.

M ETH O D S

Prof essor M arcus Feldman, Prof essor of Populat ion Biology, St anf ord Universit y, US

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Prof essor Dan W. Brock, Direct or, Cent er f or Biomedical Et hics, Depart ment of Philosophy, Brow n Universit y, US

A PPEN D I X

Prof essor Kennet h F. Schaff ner, Universit y Prof essor, George Washingt on Universit y, US

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Chapter 8 - Personality Traits Prof essor Jeff rey Gray, Emerit us Prof essor at t he Inst it ut e of Psychiat ry, Kings College London The paper commissioned on research in behavioural genet ics in t he f ield of addict ion w as used t o inf orm t he deliberat ions of t he Working Part y but w as not included as a separat e chapt er. This paper w as commissioned f rom Prof essor John C. Crabbe, Direct or, Port land Alcohol Research Cent er, and Depart ment of Behavioral Neuroscience, Oregon, US. The papers can be view ed on t he Council’s w ebsit e w w w.nuff ieldbioet hics.org.

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What do you t hink are t he likely advant ages and disadvant ages of research in behavioural genet ics?

TH E

Why study behavioural genetics?

W I TH

A summary of t he responses t o specif ic quest ions posed by t he consult at ion is set out below. It is not int ended t o const it ut e a st at ist ical analysis of t he answ ers, but t o ref lect t he issues and concerns t hat w ere raised.

C O N S U LT A T I O N

■ an emphasis on t he lack of inf ormat ion or evidence t o dat e; ■ t he complexit y of t he t opic and t he import ance of environment al f act ors as w ell as genet ic f act ors; ■ t he diff icult ies in det ermining t he ‘normal’ range, and quest ions about w ho should def ine ‘normal’ and ‘abnormal’; ■ t he import ance of seeing behaviour in t erms of it s social and cult ural cont ext .

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A consult at ion w it h t he public w as held bet w een M arch and July 2001. Approximat ely 1,500 consult at ion document s w ere disseminat ed and 111 responses w ere received f rom individuals and organisat ions. 37 w ere f rom individuals aff iliat ed t o academic inst it ut ions, 27 w ere f rom individuals w ho did not indicat e any aff iliat ion, and 44 w ere represent at ives of organisat ions. The responses came not only f rom t he UK, but also t he US, Israel, Aust ralia and New Zealand. Those w ho responded are list ed below and t he Working Part y is grat ef ul t o t hem all. Some of t he main t hemes t o emerge f rom t he consult at ion responses included:

A PPEN D I X

Appendix 2: Consultation with the public

c o n t e x t

Possible advant ages of t he research in behavioural genet ics w ere ident if ied by a number of respondent s. They included: ■ ■ ■ ■

cont ribut ion t o a bet t er underst anding of human behaviour; possible clinical applicat ions; bet t er inf ormat ion about normal variat ion; an improved underst anding of t he f ull range of f act ors t hat inf luence behaviour, including environment al f act ors.

Possible disadvant ages of t he research w ere also submit t ed, including: ■ ■ ■ ■ ■

f ear of eugenics; misuse of genet ic inf ormat ion f or commercial int erest s or exploit at ion; increased discriminat ion; erosion of individual moral responsibilit y; medicalisat ion of non-medical, or social, ‘problems’ especially t hose charact erist ics t hat should be seen as part of normal human variat ion or t hat are current ly t olerat ed by societ y, f or example homosexualit y; ■ neglect of social and environment al f act ors t hat inf luence behaviour and a t empt at ion t o overst at e t he role of genet ic f act ors; ■ misint erpret at ion or oversimplif icat ion of t he result s; ■ risk of cult ivat ing a reduct ionist view of humanit y.

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Do you t hink t hat behavioural genet ics has special f eat ures? There w as a general f eeling t hat behavioural genet ics does have special f eat ures because behaviour is int egral t o our ident it y. The research raises quest ions about consciousness and w hat it means t o be human, and is t heref ore likely t o arouse st rong f eelings. Should t here be limit s t o scient if ic inquiry in t his f ield? The most common response t o t his quest ion w as t hat t here should not be limit s t o scient if ic inquiry in t his f ield, providing t hat research is carried out w it hin def ined et hical boundaries. The cent ral problem w as seen t o be not t he research it self , but t he pot ent ial applicat ions of t he research. Public debat e about t he value and uses of t he research, and pot ent ial const raint s on t he uses of inf ormat ion w ere t heref ore seen t o be import ant . It w as f elt t o be undesirable t o censor research and several respondent s suggest ed t hat it w as bet t er t o carry out t he research in t he UK, w here it could be regulat ed, rat her t han elsew here. In your view, w ill research in behavioural genet ics have a negat ive or posit ive impact on research int o social and environment al issues? Opinion w as evenly divided on t his quest ion. Those concerned about research in behavioural genet ics f elt t hat ‘genet icisat ion’ or ‘medicalisat ion’ could mean t hat less at t ent ion w ould be paid t o educat ional and social inf luences. There w as concern t hat a f ocus on a simple det erminist ic model w ould be seen as an easy solut ion t hat government s w ould grasp. How ever, ot hers believed t hat it might have a more posit ive impact . One suggest ion w as t hat , in t he long t erm, t here might be great er concent rat ion on environment al f act ors as a result of t he improved underst anding of genet ic inf luences on behaviour. It w as also suggest ed t hat t here w as a need t o count er t he risk of adverse consequences act ively, f or example by giving parallel f unding f or genet ic and environment al research of t he same t opic t o ensure a balanced approach.

How w ill findings in research in behavioural genetics be translated into practice? Should genet ic t est s f or behavioural t rait s and personalit y charact erist ics be developed? Why, or w hy not ? Does t his apply t o all t ypes of behavioural t rait ? For genetic tests for behavioural traits to be accepted, it was suggested that several conditions needed to be fulfilled. These included the requirement that the behavioural trait or characteristic in question must be likely to present a serious danger to others or to the individual; that the gene must have a major effect on the trait; that effective therapy must be available; and, most importantly, that the test must be accurate and reliable. There was some debate whether genetic testing would give added advantages over behavioural tests that are in use already, for example psychometric tests. Some felt that genetic testing would not be any more detrimental than such evidence-based clinical assessment, while others felt that genetic tests would not be any more useful and would be unnecessary. There was consensus that no one should be forced to take a test against their will. Would t he prenat al select ion of behavioural and personalit y t rait s w it hin t he normal range be morally accept able? The vast majorit y f elt t hat t he prenat al select ion of behavioural t rait s w it hin t he normal range w ould never be morally accept able. Reasons cit ed included t hat t he f act ors t hat inf luence behaviour are not just genet ic but social and environment al, and t he relat ed point , t hat predisposit ions t o a cert ain t ype of behaviour do not mean t hat t he behaviour w ill necessarily

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What , in your view, might be t he eff ect of research in behavioural genet ics on our underst anding of healt h, illness, disabilit y and abnormalit y?

TH E PU BLI C

Is t here a moral dif f erence bet w een t he correct ion of a t rait t hought t o be t he result of a genet ic abnormalit y or def ect , and t he enhancement of t hat same t rait f or a ‘normal’ individual? If so, w hy?

W I TH

Some respondent s suggest ed t hat research in behavioural genet ics should give a bet t er underst anding of healt h and illness, leading t o import ant t herapies and improved social and pract ical support . Ot hers w ere concerned t hat t he research could also help reduce prejudice. How ever, t here w ere concerns about t he possibilit y of t he medicalisat ion of t rait s w hich are not current ly t hought of as medical problems. In addit ion, it w as suggest ed t hat behavioural genet ics could lead t o an erosion of moral responsibilit y. M any respondent s quest ioned w hat w as meant by ‘healt h’ and ‘normalit y’, and w ho should decide on t hese def init ions. It w as observed t hat f ashions, cult ures and percept ions can all aff ect how normal behaviour is def ined.

C O N S U LT A T I O N

applications of research in behavioural genetics?

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A PPEN D I X

develop lat er in lif e. It w as suggest ed t hat prenat al select ion f or behavioural t rait s could lead t o children being t reat ed as commodit ies. There w as also concern about reducing variat ion in t he gene pool, and t he diff icult y of def ining t he normal range. Only t hree out of 100 people w ho responded t o t his quest ion w ere in f avour of such prenat al select ion. How ever, pre nat al select ion f or t he avoidance of serious or lif e-t hreat ening condit ions w as t hought t o be more accept able.

c o n t e x t

Quest ions about correct ion and enhancement w ere f elt t o raise some of t he most diff icult issues of all, and opinions w ere divided. Those w ho said t here w as a moral diff erence, f elt t hat correct ion w as about rest oring f unct ion and t reat ing illness and suff ering, and w as t heref ore accept able. How ever, enhancement w as seen t o be int erf erence, or an at t empt t o render some people superior and w as t heref ore view ed in a diff erent light . The main concern w as t hat enhancement w ould lead t o t he eliminat ion of human diversit y. Some respondent s f elt t here w as no moral diff erence bet w een correct ion and enhancement . M any respondent s ref erred again t o t he diff icult y of def ining t he normal range. The boundaries bet w een normal and abnormal w ere seen t o be blurred, and changing. Cosmet ic surgery, f or example, could be f or correct ion or enhancement , and w as now increasingly accept ed. Ot her issues raised included t he mot ive f or making use of an enhancement ; t he quest ion of w hose choice it w as; and issues of t he allocat ion of resources. It w as f elt t hat enhancement could exacerbat e already exist ing social inequalit ies and lead t o great er discriminat ion. Is t he genet ic enhancement of behavioural or personalit y t rait s morally diff erent f rom enhancement by non-genet ic means such as educat ion or medical int ervent ion? The most common response w as t hat t he means of enhancement does have a moral diff erence. Non-genet ic means, it w as suggest ed, can be w it hdraw n, t erminat ed, ignored or f orgot t en. Genet ic int ervent ions w ere t hought t o be irreversible and t o have a permanent eff ect . They w ere t hus seen t o be less accept able. Concerns w ere raised about t he saf et y and eff ect iveness of germline t herapy. One of t he most import ant moral issues w as f elt t o be t he possibilit y t hat genet ic enhancement may remove or reduce t he f reedom of individuals t o consent . One 1 9 7

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respondent suggest ed t hat w hereas educat ion allow s great er f reedom of act ion, genet ic modif icat ion could do t he opposit e, enslaving an individual t o our idea of w hat t hey should be. How ever, some f elt t here w as no moral diff erence if t he end result w as t he same. If it w as accept able t o enhance a t rait by changing t he environment , it should be equally accept able t o change it genet ically. How ever, genet ic enhancement w as seen t o be less predict able. Only one respondent expressed t he view t hat genet ic enhancement of behavioural t rait s is et hically superior t o non-genet ic enhancement , t hrough educat ion, since t he f ormer makes learning a pleasure rat her t han a pain. Are t here implicat ions of research in behavioural genet ics f or our general responsibilit y f or our ow n behavioural and personalit y t rait s? Alt hough it w as f elt t o be diff icult t o predict t he likely eff ect of t he research on our concept of responsibilit y, many respondent s f elt t hat individuals might f eel less responsible f or t heir act ions if it w ere show n t hat genes have a subst ant ial inf luence on behaviour. Ot hers f elt t hat alt hough research might change t he w ay w e view personal responsibilit y, it w ould not necessarily be f or t he w orse. What are t he implicat ions f or criminal just ice, and t he legal process generally, of research in behavioural genet ics in t he areas of aggression and ant isocial behaviour? For research t o be admissible as evidence, and t hus t o have an impact on t he just ice syst em, result s w ould need t o be conclusive and reliable. This w as seen t o be unlikely in t he short t erm. How ever, if a genet ic basis f or aggression and ant isocial behaviour w as est ablished, it w as suggest ed t hat t he increase in expert w it nesses and evidence w ould need caref ul handling. Law yers w ould also need inst ruct ion in behavioural genet ics, t o ensure t hey did not misrepresent genet ic evidence. A core concern w as t hat t he criminal syst em w ould break dow n if a genet ic def ence allow ed pleas of no f ree w ill. It w ould be diff icult t o assign responsibilit y f or act s. Respondent s asked w het her a person w ho has a predisposit ion t o aggression deserves credit f or not responding t o provocat ion, and conversely, w het her a person w ho has a predisposit ion t o placid behaviour be punished more severely f or a violent act ? On t he posit ive side how ever, it w as suggest ed t hat research in behavioural genet ics could inf luence t he met hods used t o punish, t reat or educat ion off enders, w it h a syst em based on t reat ment w here possible. In your view, might research in behavioural genet ics height en or reduce discriminat ion, st ereot yping and social discriminat ion bet w een groups? The majorit y of respondent s f elt t hat research in behavioural genet ics w ould height en discriminat ion, by making st ereot yping easier and leading t o t he creat ion of a genet ic underclass. How ever, a f ew people f elt t hat discriminat ion could be reduced, if bet t er know ledge helped reduce f ear and encourage underst anding and sympat hy. The Inst it ut e of Alcohol St udies, f or example, suggest ed t hat t he discovery of a st rong genet ic cont ribut ion t o problem drinking could possibly reduce st igma. By giving addit ional credence t o t he concept of alcoholism or addict ion more generally as a disease, t he condit ion w ould become less likely t o be regarded as self inf lict ed and caused by w eakness of w ill or irresponsibilit y. Several respondent s f elt t hat in t he

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The hope w as expressed t hat healt h prof essionals and ot hers could use genet ic inf ormat ion t o improve t reat ment and w elf are provision. Educat ional aut horit ies could use t he inf ormat ion eit her posit ively or negat ively. There could be st reaming of children according t o t heir IQ score, discriminat ion against t hose disposed t ow ards aggressiveness or low int elligence, or educat ion programmes t arget ed according t o an individual’s genet ic pot ent ial. The use of genet ic inf ormat ion by government s w as f elt t o be a mat t er of concern, part icularly if poor or inconclusive evidence w as used. Several respondent s w ere w orried t hat t hose in a posit ion t o misuse inf ormat ion w ould invade a person’s privacy and discriminat e against t hem. Discriminat ion by employers w as t hought t o be a part icular problem. How ever, a pot ent ial benef it , f rom t he perspect ive of healt h and saf et y, w as t hat some people may be helped by ensuring t hey w ould not be placed in environment s w hich w ould be especially hazardous t o t hem.

W I TH

How might healt h prof essionals, government s, employers, insurers, educat ion aut horit ies and ot hers use genet ic inf ormat ion concerning human behaviour?

C O N S U LT A T I O N

There w as concern t hat genet ic know ledge about behavioural t rait s could be divisive and cause discriminat ion. The impact on an individual w ould depend w het her t here w as a t herapy. If t here w as not a possible t reat ment , know ledge could lead t o individual despondence and hopelessness. Families may be put under pressure t o t ake act ion and seek a ‘cure’. Communit ies may be less w illing t o help t hose w it h challenging behaviour t hat could have been avoided, alt hough t here may also be increased sympat hy. The import ance of genet ic counselling and educat ion of t he public w as emphasised.

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What do you t hink w ill be t he impact of genet ic know ledge about behavioural t rait s on t he individual, on f amilies and on communit ies?

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short -t erm discriminat ion w ould be height ened, but in t he long-t erm it could be reduced. If diff erences w ere show n t o be normal and unavoidable, t here might be increased t olerance. Social discriminat ion bet w een groups might also be reduced if research show ed how much great er genet ic variat ion is among individuals t han among groups. It w as also point ed out t hat it w as not t he research it self , but t he uses t o w hich it w as put t hat w ould lead t o discriminat ion.

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There w as also concern t hat insurers w ould use genet ic inf ormat ion t o increase discriminat ion. Respondent s f rom w it hin t he insurance indust ry off ered diff erent view s as t o w het her such inf ormat ion w ould be of use. Are t here any circumst ances w hen such inf ormat ion should be available t o t hird part ies eit her w it h or w it hout t he consent of t he individual? Respondent s f elt t hat t he only circumst ances w hen such inf ormat ion should be available t o t hird part ies w ould be if it w ere in t he public int erest , t hat is, if it w ere t he case t hat not t o do so could put t he individual or ot her people in danger. It w as also f elt t he inf ormat ion should be available in some criminal cases. How ever, several respondent s added t hat t he inf ormat ion should only be made available t o qualif ied people, and t hat it must be w it h t he consent of t he individual. How can w e ensure t hat consent t o t he disclosure of such inf ormat ion is properly inf ormed and f reely given? The use of genet ic inf ormat ion w as seen t o be one of t he core issues, and t he import ance of consent , conf ident ialit y and appropriat e use of inf ormat ion w ere emphasised. Some

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respondent s suggest ed t hat st ringent new regulat ion w ould be necessary w hile ot hers f elt t hat an ext ension of t he current syst em f or disclosure of medical records could be appropriat e. Inf ormat ion should only be disclosed t o a t hird part y f ollow ing proper inf ormed consent f rom t he individual concerned. In any event , t here w as seen t o be a need f or high qualit y behavioural genet ic counselling. Given t he complex and sensit ive nat ure of research in behavioural genet ics, how can members of t he public best be inf ormed about it ? It w as f elt t o be ext remely import ant t hat t he public should be inf ormed as f ully as possible, w it h open and t ransparent debat e. Suggest ions as t o st rat egies f or achieving t his aim included sensit ive and int elligent media coverage, responsible t elevision document aries, a soap opera st ory line, public post ers, cit izenship classes in schools, and public debat es and discussion meet ings. One respondent suggest ed an off icial body should be est ablished t o ensure media report s are not simplist ic and misleading. Do you t hink t hat research in behavioural genet ics and genet ic t est s f or behavioural t rait s might require new codes of pract ice or new regulat ory cont rols? What in your view should be t he nat ure of such codes of pract ice or cont rols? M ost respondent s f elt t hat new codes of pract ice and regulat ory cont rols w ould be necessary. Several people suggest ed t hat a st at ut ory regulat ory body, similar t o t he Human Fert ilisat ion and Embryology Aut horit y, should be est ablished. An alt ernat ive w as a nat ional et hics commit t ee t hat w ould f ocus specif ically on research in behavioural genet ics. Ot hers f elt t hat int ernat ional regulat ion w ould also be import ant , f or example t hrough t he Unit ed Nat ions. Regulat ion in t his area should be kept under cont inuous review. Some respondent s t ook t he view t hat current codes might be suff icient . How much priorit y w ould you accord research in behavioural genet ics in t he compet it ion f or necessarily limit ed research f unds? The majorit y of respondent s f elt t hat research in behavioural genet ics should be given low priorit y. Some specif ied t hat research should remain w it hin t he public domain, or t hat environment al f act ors should be given more priorit y. Six respondent s expressed t he view t hat such research should be given no priorit y at all, w hile only one suggest ed it should be given t he highest priorit y possible. The diff icult y of separat ing out genet ic research int o normal t rait s f rom t hat int o diseases, and t he diff icult y in separat ing research int o genet ic inf luences f rom t hat int o environment al inf luences on behaviour, w ere highlight ed.

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The Working Part y w ishes t o t hank t he f ollow ing individuals and t heir organisat ions f or t heir int erest ing and helpf ul responses:

Organisations

Associat ion of Brit ish Insurers Associat ion of Brit ish Pharmaceut ical Indust ry The Bioet hics Advisory Commit t ee of t he Israel Academy of Sciences and Humanit ies and t he Israel Helsinki Commit t ee f or Human Genet ic Research Brit ish M edical Associat ion Brit ish Psychological Societ y Church of Scot land Board of Social Responsibilit y Christ ian M edical Fellow ship Cumbria-West morland Federat ion of Women’s Inst it ut es Derbyshire Federat ion of Women’s Inst it ut es East Berkshire Research Et hics Commit t ee

PU BLI C

Consumers’ Associat ion

TH E

Cent re f or Bioet hics and Public Policy

W I TH

Christ ian Act ion Research and Educat ion

C O N S U LT A T I O N

Associat ion of M edical Research Charit ies

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Academy of Learned Societ ies f or t he Social Sciences

A PPEN D I X

Responses to the public consultation

c o n t e x t

East Kent Federat ion of Women’s Inst it ut es East Suff olk Local Research Et hics Commit t ee (LREC) East Yorkshire Federat ion of Women’s Inst it ut es GeneWat ch UK Genet ic Int erest Group Genet ics Group of t he Facult y and Inst it ut e of Act uaries GlaxoSmit hKline Gloucest ershire Federat ion of Women’s Inst it ut es Human Fert ilisat ion and Embryology Aut horit y Human Genet ics Alert Human Genet ics Commission Inst it ut e of Alcohol St udies Inst it ut e of Psychiat ry, King’s College London: Depart ment of Forensic Psychiat ry Isle of M an Freet hinkers Lot hian Research Et hics Commit t ee M edical Research Council M ind The Nat ional Council of Women of Great Brit ain Nat ional Federat ion of Women’s Inst it ut es Nat ional Foundat ion f or Gif t ed and Creat ive Children Nat ional Schizophrenia Felloship

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G e n e t i c s

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Nort hallert on LREC Nort h Not t inghamshire LREC One-in-a-Thousand Societ y Alzheimer’s Societ y Carers Nat ional Associat ion Public Healt h Genet ics Net w ork Royal College of Nursing Royal College of Paediat rics and Child Healt h Royal College of Psychiat rist s: Et hics Sub-commit t ee The Wellcome Trust

Individuals Dr Bill Albert Dr M ichael Ant oniou and Janey Ant oniou Dr M ark Bailey Chris Barchard Rev St ephen Bellamy: Vicar of St . James’, Birkdale Lesley M Bosw ort h Prof essor Robert Boyd: Principal, St . George’s Hospit al M edical School Janet Bryden Pet er Bryden Adam Buick Prof essor C.C.H. Cook: Prof essor of t he Psychiat ry of Alcohol M isuse, Universit y of Kent at Cant erbury A.B. Dunlop: Lot hian Et hics of M edical Research M erinda Fargher St ephen Finlan Dr David S. Gordon M r and M rs SH Hext er David Hill C.A. Hobby Samant ha Hodge M ark How it t Dr G Royden Hunt : Cent re f or Lif elong Learning, Cardiff Universit y James B Jack M arjorie Kat jire Dr Ant hony Kessel: London School of Hygiene and Tropical M edicine Dr Jenny Lew is Alist air C M acDonald Dr Calum M acKellar Sandra M acPhee Fiona M cCandless: School of Nursing, Universit y of Not t ingham Gail M annion: Genet ic Associat e, M ember of Liverpool Healt h Aut horit y Paediat ric Et hics Commit t ee 2 0 2

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James M iles St ephen M ilt on Gaynor M it chell Hilary M urray: President , M anchest er M edical Et hics Group Ainsley New son: Et hics Unit , M urdoch Children’s Research Inst it ut e, Aust ralia Dr Ian K. Pople Bet t y Rat hbone: Clinical Psychologist Dr Ann Richardson: Independent Research Consult ant M ervyn Richardson Robin Root es

Roy G. Silson Jonat han Sussex

PU BLI C

Prof essor St even Rose: Prof essor of Biology and Direct or, Brain and Behaviour Research Group, Open Universit y and Joint Prof essor of Physic, Gresham College

TH E

Prof essor Hilary Rose: Visit ing Research Prof essor in Sociology, Cit y Universit y; Joint Prof essor of Physic (w it h ref erence t o genet ics and societ y), Gresham College and Prof essor Emerit us of Social Policy, Universit y of Bradf ord

W I TH

M at t Ridley

C O N S U LT A T I O N

Emilio M ordini; Psychoanalyt ic Inst it ut e f or Social Research, It aly

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Gemma M onks

A PPEN D I X

Prof essor Theresa M art eau: King’s College London

c o n t e x t

Prof essor R. Tallis: Depart ment of Geriat ric M edicine, Universit y of M anchest er M ark Taylor: Law Facult y, Universit y of Sheff ield Grant D Vallance: Depart ment of Philosophy, Open Universit y Rev. FCM Van Den Broeder Prof essor Veronica van Heyningen At t am Vet t a David Vile: Research Psychologist , St James’ Hospit al, Dublin Prof essor Dorot hy C. Wert z, Universit y of M assachuset t s M edical School, Shriver Division, US Ian Whit t aker Pet er Windle

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Addit ive genet ic variance: Variat ion due t o t he eff ect s of numerous genes w hich combine in a linear f ashion, each gene cont ribut ing a relat ively small eff ect t o a phenot ypic f eat ure. See also non-addit ive genet ic variance.

G LO SSA RY

Glossary

Allele: A variant f orm of a gene, w hich diff ers in DNA sequence f rom alt ernat ive alleles of t he same gene. Am ino acid: A molecule w hich serves as t he building block of prot eins. Prot eins have diff erent charact erist ics as det ermined by t he sequence of amino acids. Genes specif y t his sequence. Associat ion st udies: An associat ion st udy compares t he f requency of a part icular genet ic variant in a group of people w it h a part icular t rait w it h a mat ched set of cont rols (a similar group of people not displaying t he charact erist ic). Balanced polym orphism : The maint enance of t w o or more diff erent alleles in a populat ion because each is advant ageous over t he ot her under part icular circumst ances. Behavioural genet ics: The f ield of research t hat at t empt s t o quant if y t he genet ic cont ribut ion t o behaviour and locat e specif ic genes, or groups of genes associat ed w it h behavioural t rait s, and t o underst and t he complex relat ionship bet w een t hese genes and t he environment . Candidat e gene: A gene suspect ed t o cont ribut e t o a disease or behavioural t rait by virt ue of know ledge of it s f unct ion and/or chromosomal posit ion. Chrom osom e: The t hread-like DNA in a cell is divided int o several separat e lengt hs. Each lengt h f orms a st ruct ure called a chromosome. M ost mammalian cells cont ain t w o copies of every chromosome, w it h t he except ion of sex chromosomes in males. Human cells cont ain 23 pairs of chromosomes. Concordance: The rat e of co-occurence of a phenot ype bet w een individuals (f or example, pairs of t w ins). Dizygot ic (DZ) t w ins: Dizygot ic t w ins arise w hen t w o eggs are released and f ert ilised separat ely. They are also know n as f rat ernal or non-ident ical t w ins. DNA (deoxyribonucleic acid): The chemical subst ance of w hich a gene is made and w hich encodes genet ic inf ormat ion. Dom inant /dom inance: The f orm of inherit ance in w hich a genet ic variant has an eff ect w hen it is present in only one of a pair of chromosomes. See also recessive. Eff ect size: The proport ion of individual diff erences f or a t rait in t he populat ion account ed f or by a part icular f act or. For example, in molecular genet ics st udies, t he eff ect size of a gene is t he proport ion of variance t hat t he gene is t hought t o explain. Egalit arian: A t ype of et hical or polit ical posit ion t hat seeks t o minimize unjust if iable inequalit ies bet w een people, especially inequalit ies in t he opport unit ies open t o t hem. Em bryogenesis: The phase of prenat al development w herein an embryo develops. Environm ent : The environment is t aken t o include everyt hing t hat inf luences a person’s phenot ype, apart f rom t heir genot ype. It is underst ood very broadly in research in behavioural genet ics.

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Epidem iological research: Research relat ing t o t he dist ribut ion and det erminant s of healt hrelat ed st at es or event s in specif ied populat ions, and t he applicat ion of t his st udy t o t he cont rol of healt h problems. Epist asis: The masking or unmasking of t he eff ect s of one gene by t he act ion of anot her. For inst ance, a gene t hat causes complet e baldness w ould be epist at ic w it h a gene t hat det ermines hair colour. Epist at ic eff ect s cont ribut e t o non-addit ive genet ic variance. Eugenics: The lit eral meaning of t he t erm eugenics is ‘w ell born’. It ref ers t o t he doct rine t hat humanit y can be improved by select ive breeding, t hat is, by encouraging t hose w it h desirable t rait s t o reproduce or discouraging t hose w it h undesirable t rait s f rom doing so. Founder eff ect : The principle t hat w hen a small sample of a larger populat ion est ablishes a colony in a new locat ion, it s gene pool carries only a f ract ion of t he genet ic diversit y represent ed in t he original populat ion. Changes in t he f requency of alleles are likely t o occur as a result of diff erent evolut ionary pressures operat ing on diff erent gene pools. g (general cognit ive abilit y): A concept derived f rom st at ist ical analysis t hat ref ers t o t he common f act or measured by diff erent int elligence t est s. Gam et es: A gamet e is a cell involved in sexual reproduct ion (egg or sperm) and cont ains only one copy of each chromosome. Gene: The f undament al physical and f unct ional unit of heredit y consist ing of a sequence of DNA, occupying a specif ic posit ion w it hin t he genome. Gene-environm ent correlat ion: The genet ic inf luence on exposure t o environment . Children not only inherit genes f rom t heir parent s but are also exposed t o environment s t hat are shaped by t heir ow n and t heir parent ’s genet ic makeup. Gene-environm ent int eract ion: Genet ic suscept ibilit y t o environment s. The impact of environment al f act ors may diff er depending on a person’s genet ic makeup. Gene expression: The process by w hich inf ormat ion cont ained in a gene is t ranscribed t o produce f unct ional RNA molecules w hich are t hen t ranslat ed t o produce prot eins. Genet ic det erm inism : The view t hat a person's genes det ermine by t hemselves import ant charact erist ics of a person, such as t heir charact er or int elligence. Genet ic drif t : The random f luct uat ions of gene f requencies due t o sampling errors. While drif t occurs in all populat ions, it s eff ect s are most evident in very small populat ions. Genet ic m arker: Any locus t hat , by virt ue of allelic variat ion bet w een individuals, serves t o dist inguish one group of chromosomes f rom anot her at a part icular locat ion. Depending on t he cont ext , microsat ellit es, SNPs and polymorphisms in prot eins may all serve as genet ic markers. Genet ic variat ion: The presence of diff erent combinat ions of alleles in diff erent individuals in a populat ion. Genom e: The t ot al genet ic complement of an individual or of a species. Genot ype: An individual’s genot ype is t heir ent ire genet ic const it ut ion, as dist inguished f rom t heir physical charact erist ics. See also phenot ype. Germ line gene t herapy: An experiment al process of insert ing genes int o germ cells or f ert ilised eggs in order t o correct a heredit ary disease. The new genet ic mat erial can be passed on t o off spring. See also somat ic gene t herapy. 2 0 6

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Herit abilit y: A st at ist ical est imat e of how much of t he t ot al variat ion in a populat ion can be explained by genet ic diff erences. Broad-sense herit abilit y includes bot h addit ive genet ic variance and non-addit ive genet ic variance. Narrow -sense herit abilit y ref ers only t o addit ive genet ic variance.

G LO SSA RY

Haploinsuff iciency: A sit uat ion in w hich t he prot ein produced by a single (normal) copy of a gene pair is not suff icient t o assure normal f unct ion.

Het erozygot e: An individual is said t o be a het erozygot e w hen t he t w o alleles at a part icular locus are diff erent . Hom ozygot e: An individual is said t o be a homozygot e w hen t he t w o alleles at a part icular locus are ident ical. Knockout m odels: Animal models in w hich a specif ic gene has been inact ivat ed. Lesion m odels: An animal model in w hich t he f unct ion of an organ is st udied by causing a specif ic injury or disease t o occur. Linkage disequilibrium : When alleles at t w o dist inct ive loci occur t oget her in gamet es more f requent ly t han expect ed, t he alleles are said t o be in linkage disequilibrium. Evidence f or linkage disequilibrium can be helpf ul in mapping disease genes since it suggest s t hat t he t w o may be very close t o one anot her. Locus: The sit e of a specif ic gene on a chromosome. M endelian disease: A disease w hich f ollow s t he pat t erns of inherit ance originally ident if ied by Gregor M endel. M icrosat ellit es: M icrosat ellit es cont ain t andem repeat s of a simple DNA sequence t hat vary in number and are usually of no f unct ional signif icance. Because t hese repeat lengt hs are usually st ably inherit ed f rom generat ion t o generat ion, diff erences in t he dist ribut ion of repeat lengt hs bet w een t w o populat ions may indicat e diff erences in t heir genet ic origins. M olecular genet ics: M olecular genet ic met hods involve st udying genes at t he level of t he nucleot ide sequence. M onozygot ic (M Z) t w ins: M onozygot ic t w ins arise f rom a single f ert ilised egg and are t heref ore assumed t o be genet ically ident ical. They are also know n as ident ical t w ins. M ult if act orial: A t erm w hich denot es t hat many f act ors, bot h genet ic and environment al, cont ribut e t o t he development of a disease. M ut agenesis: A process t hat result s in modif icat ion of DNA sequence. See also mut at ion. M ut at ion: The modif icat ion of a DNA sequence t hat can pot ent ially result in a change in t he f unct ion of a gene. M ut at ions may be caused by mist akes during cell division, or t hey may be caused by exposure t o DNA-damaging agent s in t he environment . M ut at ions can be harmf ul, benef icial, or have no eff ect . If t hey occur in cells t hat make eggs or sperm, t hey can be inherit ed; if mut at ions occur in ot her t ypes of cells, t hey are not inherit ed. Non-addit ive genet ic variance: Variat ion due t o t he eff ect s of numerous genes w hich combine t o have an eff ect in a non-linear or int eract ive f ashion. See also addit ive genet ic variance. Non-shared environm ent : Environment al inf luences t hat make f amily members diff erent f rom each ot her. See also shared environment .

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Nucleotide: Nucleotides are the subunits from which DNA and RNA molecules are assembled. A nucleotide is a base molecule (adenine, cytosine, guanine or thymine in DNA; adenine, cytosine, guanine or uracil in RNA), linked to a sugar molecule and phosphate groups. Nucleotides combine in groups of three to code for amino acids. Ontogeny: The development of an individual from fertilisation to maturity. Over-expression: Greater than normal production of a gene product, for example a protein or RNA molecule, from a gene. Many animal studies involve the over-expression of a gene in order to determine the function of its product. See also under-expression. Phenotype: The observable or measurable traits of an individual as produced by its genotype and the environment. Phylogeny: The relationship of groups of organisms as reflected by their evolutionary history. Pleiotropy: The phenomenon in which a single gene gives rise to a number of seemingly unrelated characteristics. Polygenic: A disease or trait is said to be polygenic when it is influenced by more than one gene. Polymorphism: Where two or more alleles exist for a gene, such that at least two of the alleles are present in more than 1% of the chromosomes in a population. Population variation: The range of differences between individuals in a population. Preimplantation genetic diagnosis: A technique used to determine whether an embryo created by in vitro fertilisation carries a genetic disease or trait, prior to it being implanted in the uterus. Prenatal diagnosis: Determining whether a fetus has a disease or trait. Protein: Proteins are biological molecules that are essential for all life processes and are encoded by an organism’s genome. A protein consists of chains of amino acid subunits and its function depends on its three-dimensional structure, which is determined by its amino acid sequence. Quantitative genetics: Quantitative genetic methods are used to estimate the effect of genetic and environmental influences on variation of a trait within a population. Research into quantitative genetics uses statistical methods to examine and compare groups of people without focusing on particular genes. Quantitative Trait Locus (QTL) analysis: A technique for identifying genes that influence polygenic traits varying between individuals in a continuous fashion. Recessive: The form of inheritance where a genetic variant causes little or no outward effect unless it is present in both of a pair of chromosomes and therefore has been inherited from both parents. See also dominant . RNA (ribonucleic acid): A single stranded nucleic acid molecule comprising a linear chain made from four nucleotides, whose sequence determines the informational content of the molecule. RNA is produced by transcription from DNA and may either be translated into protein or may itself play a functional role. Shared environment: Environmental influences that make family members more similar are said to be part of the shared environment. See also non-shared environment. Single nucleotide polymorphism (SNP): SNPs are single DNA base pair variations. In the human genome project they are being used as genetic markers to locate genes that cause disease or 2 0 8

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Somatic gene therapy: An experimental process of inserting genes into any cell other than a germ cell for therapeutic purposes. The new genetic material cannot be inherited by offspring. See also germ-line gene therapy.

G LO SSA RY

influence behaviour or other traits. Most SNPs fall within the non-coding regions of human DNA and make no difference to the individual.

Stratification: This refers to a problem with association studies where there are subtle, but undetected differences in the populations from which the cases and matched controls were sampled. In this situation, differences in allele frequency might simply reflect the background evolutionary differences between the two samples, rather than reflecting true trait-specific differences. Susceptibility allele: An allele which is associated with a predisposition to a trait. Transcription: The process by which a gene’s DNA sequence is copied into RNA. Translation: The process by which RNA directs the synthesis of a protein. Transgenic: An organism into which foreign DNA has been experimentally transferred. Under-expression: Lower than normal production of a gene product from a gene. See also overexpression. Zygosity: Twins are referred to as monozygotic or dizygotic based on whether they were derived from a single zygote (and thus are considered to be genetically identical) or not. Zygote: A cell with two sets of chromosomes produced by the fusion of male and female gametes. A fertilised egg.

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ABI ACGT ADA ADHD AID CARE CBCL CIPD CPI DDA DNA DPA DRC DRD4 DSM -IV DZ EC ECHR ERA EST EU FDA g GAD GAIC GTAC HFEA HGAC HGC IGF2R INAH IQ IVF M AOA M M PI M PQ M RC MZ NHS PAH PGD PKU PND QTL SAD SNP UNESCO

Associat ion of Brit ish Insurers Advisory Commit t ee on Genet ic Test ing Americans w it h Disabilit ies Act 1990 At t ent ion Def icit Hyperact ivit y Disorder Art if icial inseminat ion by donor Christ ian Act ion Research & Educat ion Child Behaviour Check List Chart ered Inst it ut e f or Personnel and Development Calif ornia Psychological Invent ory Disabilit y Discriminat ion Act 1995 Deoxyribonucleic acid Dat a Prot ect ion Act 1998 Disabilit y Right s Commission Dopamine recept or D4 gene Diagnost ic and St at ist ical M anual of M ent al Disorders, f ourt h edit ion Dizygot ic European Communit y European Convent ion on Human Right s and Fundament al Freedoms Employment Right s Act 1996 Expressed sequence t ag European Union Food and Drug Administ rat ion (US) General cognit ive abilit y Generalised anxiet y disorder Genet ics and Insurance Commit t ee Gene Therapy Advisory Commit t ee Human Fert ilisat ion and Embryology Aut horit y Human Genet ics Advisory Commission Human Genet ics Commission Insulin-like grow t h f act or 2 recept or Int erst icial nuclei of t he ant erior hypot halamus Int elligence quot ient In vit ro f ert ilisat ion M onoamine oxidase A M innesot a M ult iphasic Personalit y Invent ory M ult idimensional Personalit y Quest ionnaire M edical Research Council M onozygot ic Nat ional Healt h Service Phenylalaninehydroxylase gene Pre-implant at ion genet ic diagnosis Phenylket onuria Prenat al diagnosis Quant it at ive t rait locus Social anxiet y disorder Single nucleot ide polymorphism Unit ed Nat ions Educat ional, Scient if ic and Cult ural Organizat ion

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Glossary of Abbreviat ions and Acronyms

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I N D EX

Index abortion see termination of pregnancy access, to interventions xxvi–xxvii, 145–6 Achenbach Child Behaviour Checklist 89 achievements, value of individual 143 additive genetic variance 40, 111 in intelligence 75–6 adoption studies 44–5 criminal behaviour 92 intelligence 72 personality 83 sexual orientation 101–2 ‘adverse selection’ 186–7 Advertising Standards Authority xxviii, 147 Advisory Committee on Genetic Testing (ACGT) xxvii, 147, 182 see also Human Genetics Commission age heritability of IQ and 73 of onset (of a trait) 30 aggression 90, 160 animal research 95–6 biological explanations 160–1, 162 heritability 92 insurance issues 187 legal responsibility 162, 163 see also violence Agreeableness 81, 82 quantitative genetics 83 alcoholism 136 DRD4 gene and 51 genetic variant protecting against 49, 112 aldehyde dehydrogenase (ALDH) gene variant 49 al-Ghazali 123 alleles 29 processes influencing frequency 30–1 susceptibility 30, 49–53 see also human genetic variance alpha-1 antitrypsin deficiency 33 Alzheimer’s disease 59, 74 Americans with Disabilities Act 1990 (ADA) 178, 179 anger management 167 animal models 57–63 advantages 60–1 disadvantages 61–3 methods of creating 58–9 species used 57–8 see also mouse models animals research using xxi, 27, 57–63 antisocial behaviour 95–6 intelligence 74 personality traits 85–6 reporting xxiii–xxiv sexual orientation 103 selective breeding 14, 58–9 anterior commissure 104 antisocial behaviour 8, 89–96 adoption studies 44–5 animal research 95–6 applications of current research 113 assortative mating 92 biological explanations 159–62 definition and measurement 89–91 environmental influences 41, 96, 166 exculpation 162–6

future research directions 96 medicalisation 165 molecular genetics 95, 96, 161–2 prediction xxxii, 160, 168–71 quantitative genetics 91–4 selection and testing in education 183–4 sentencing and treatment 166–8 sex differences in heritability 94 as social construct 159 see also criminal behaviour antisocial personality disorder 89 antisocial personality traits 90, 92 anxiety animal research 62 medicalisation 137–8 molecular genetics 84–5, 112 apolipoprotein E, 2 allele 31 aptitude tests 175 Aricept (donepezil) 144 Aristotle 123 artificial insemination by donor (AID) 16 ascertainment bias 105 Association of British Insurers (ABI) 185, 186 association studies 51–2 assortative mating 92, 149 Attention Deficit Hyperactivity Disorder (ADHD) 160 diagnostic spread 137 DRD4 gene and 51 Australian Twin Study of Sexual Attitudes and Behaviour 107 autism 136 autonomy in criminal law 162–3 see also freedom/free will Averroes (Ibn Rushd) 123 Avicenna (Ibn Sina) 123 Barchard, Chris 13 battered child syndrome 161 battered spouse syndrome 161 behaviour describing human 35 evidence for genetic influences xxiv legal responsibility 159–71 medicalisation 135–9 normal range see normal behaviour prediction from genetic information 36 behavioural genetics 5, 27–36 animal research 27, 57–63 complexity 5–6 ethical issues xxiv–xxxi and eugenics xx–xxi, 13 focus 27 funding research xxxiii, 114–15 historical context xx–xxi, 13–22 legal issues xxxi–xxxii personal identity/responsibility and 121–30 policy issues xxxii–xxxiii practical applications xxiv–xxv, 133–5 reporting research xxii–xxiv, 113–14 reviews of evidence 111–15 science xxi–xxiv scope 8 behavioural traits difficulty of defining and measuring 111

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interventions 134–5 predictability 36, 133 role of genes in causation 32–4 selecting and changing 133–56 terminology 8 behaviourist psychology 20 The Bell Curve (Herrnstein & Murray) 21, 71 bisexuality 101, 102 blood pressure, high 32 body symmetry, IQ and 77 body types, criminals 159 brain structure heritability 75 sexual orientation and 104 volume, IQ and 75 breeding selective 6, 13, 14 see also eugenics British Eugenics Society 16, 17 British Psychological Society 13 Buss–Durkee hostility scales 90 California Psychological Inventory (CPI) socialisation scale 90 Canada, eugenic practices 15 candidate genes 49, 52 causation criminal behaviour 165 role of genes xxi–xxii, 32–4, 52 cells 29 Chart ered Inst it ut e f or Personnel and Development (CIPD) 175 Charter of Fundamental Rights of the European Union (EU 2000) 176–7 chemicals mutagenic 59 prenatal exposure 104 children disruptive/hyperactive 137, 138 environmental interventions 135 genetic tests 142–3, 170–1 maltreatment/abuse 95, 113, 162, 170 relations with parents xxx–xxxi, 154, 155, 156 right to an open future 154 see also education China 17 choice, individual 142–3 Christianity 122 chromosomes 28 Ciba Foundation 15 clinical genetics 16, 18 Clothier Report (Report of the Committee on the Ethics of Gene Therapy) xxvi, 134–5, 141 see also gene therapy Code of Practice and Guidance on Human Genetic Testing Services Supplied Direct to the Public (Advisory Committee on Genetic Testing) xxviii, 147 cognitive therapy 167 communication, research results xxii–xxiv, 113–14 Communities that Care 170 complex traits 42 conduct disorder 89, 92, 160 confidentiality 175, 180–1 Conscientiousness 81, 82, 83 consent 170–1, 175, 181 consumer protection xxviii, 147 Consumers’ Association xxix, 148, 186 Convention for the Protection of Human Rights and Dignity

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of the Human Being with Regard to the Application of Biology and Medicine: Convention on Human Rights and Biomedicine (Council of Europe 1997) 134, 176 cosmetic orthopaedics 142 cosmetic surgery 142, 144 criminal behaviour (including offending) 89–90 biological explanations 159–62 definition and measurement 89–90 exculpation 160, 162–6 heritability 92, 93–4 prediction xxxii, 168–71 responsibility for xxxi–xxxii, 159–71 sentencing and treatment xxxi, 160, 166–8 as social construct 159 see also antisocial behaviour criminal law 159–71 critical illness insurance 186, 187 culpability, diminished 166 culture 128–9 cystic fibrosis 32, 134, 149 Darwin, Charles 14, 19 Data Protection Act 1998 (DPA) 180–1 Davis, Deena 154 delinquency 90 applications of current research 113 heritability 92, 93 sentencing and treatment 166 dementia 161 deoxyribonucleic acid (DNA) 28 depression 7, 114 postnatal 161 ‘designer babies’ xxix–xxx, 149–50 determinism 123–4, 125, 126 developmental psychology 22, 39 diagnostic categories, widening of xxx, 136–9 diagnostic procedures, compulsory 170 Diagnostic and Statistical Manual for Mental Disorders (DSM), homosexuality 99 Diamond Blackfan anaemia 149 diet, changes in 135 dignity, human xxiv, 121, 130 diminished culpability 166 diminished responsibility xxxi, 164, 165–6 disability 178, 179 Disability Discrimination Act 1995 (DDA) 179, 183 Disability Rights Commission (DRC) 183 discrimination laws 178–9 disease causation 32–3 therapy 144 dismissal, unfair 180 DNA 28 dominance 30, 75 donors gamete 16, 150 for siblings, selection of embryos as xxx, 149, 150 Doogie mice 59–60 dopamine 84 dopamine D4 receptor (DRD4) 49, 51, 84, 112 driving insurance 187 drug abuse 51 drugs as interventions see medical interventions regulating provision xxix, 148 safety 141 Duchenne’s muscular dystrophy 32, 149 Dworkin, Ronald 146

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Charter of Fundamental Rights (2000) 176–7 discrimination laws 178–9 evidence, for genetic influences on behaviour xxiv evolution, homosexuality 106–7 evolutionary psychology 8, 21–2 exculpation, genetic information for 160, 162–6, 171 expression analysis 60 ‘expressivist’ position, prenatal selection 153 Extraversion 8, 81, 82, 83 extremes analysis 44 versus normal variation 44, 45 Eysenck, Hans 20, 81

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education xxxiii, 175, 183–4 educational attainment gamete donors 151 IQ scores and 71 egalitarianism xxvii, 146, 153–4 eggs, selection of donor 151 eliminativist position 125–6, 127–8 embryo biopsy 148 selection xxx, 148–9, 150, 152 see also pre-implantation genetic diagnosis emotionality animal model 85–6 negative 114 emphysema 33 employment xxxii–xxxiii, 175, 177–83 current legal framework 177–8 discrimination laws 178–9 earlier reform proposals 181–2 privacy and confidentiality 180–1 testing for behavioural traits 182–3 unfair dismissal 180 Employment Rights Act 1996 (ERA) 180 endophenotypes 34 see also ‘intermediate phenotype’ enhancement, versus therapy xvi–xxvii, 144–5 environment (environmental factors) 27 in allele selection 30 in antisocial behaviour 41, 96, 166 in disease causation 33 estimating influence 41 family, twin and adoption studies 42–5 intelligence 19, 41, 72 non-shared 41, 84 relationship with genes 33, 34 shared 41 environmental interventions 21, 134, 135 choice 142 effectiveness 140 monitoring provision xxix, 148 reversibility 142 safety 140 epigenetic effects 29 epistasis 75 Equal Employment Opportunity Commission 179 equal environments assumption, twins 43 equality of opportunity xxvii, 145–6 prediction of antisocial behaviour and 170 prenatal selection and 153–4 Equal Treatment Directive 76/207/EEC 178, 179 ethical issues xxiv–xxxi Ethics Committee of the American Society of Reproductive Medicine 150 ethnic origin see race/ethnic origin eugenics xx–xxi, 6, 13–22 in EU Charter 176–7 history 14–16 impact on research into behaviour 18–22 links to behavioural genetics 13 negative 14, 17 positive 14 unacceptability of past practices 16–18 European Convention on Human Rights and Fundamental Freedoms (ECHR) 180 European Group on Ethics in Science and New Technologies 177 European Union (EU)

facially neutral standardised tests 178 factor analysis 70, 83 Faculty and Institute of Actuaries 186 family reporting of sexual orientation 100 risk factors for criminal behaviour 166 role in affecting behaviour 41 family history 187 family studies 42, 45 sexual orientation 100–1 fatalism xxv, 123–4, 135 ‘feeble minded’ 14 Feinberg, Joel 154 female homosexuality biological influences 104 quantitative genetics 100–1, 102 see also sexual orientation females, antisocial behaviour 94 Field Medal winners 151 ‘fierce’ mutation 96 finger-length ratios 104 fingerprint ridge asymmetry 104 fluoxetine (Prozac) 85 fluvoxamine (Luvox) 137 Flynn effect (secular increase in IQ) 41, 69 folk psychology 125–6, 127–8 Food and Drug Administration (FDA) xxvi foodstuffs xxix, 148 fragile X syndrome 73 freedom/free will xxiv, 122, 124–5, 130 in criminal law 162–3 reproductive see reproductive freedom restriction of child’s 154 fruit fly 62, 103 functionalist position 126–7, 128, 130 funding, research xxxiii, 114–15 g (general cognitive ability) 52, 70, 76 Galton, Francis 14, 17, 18–20 gamete selection xxix, 16, 149, 150 Gay Brothers Study 107 ‘gay gene’ 102–3, 105, 113 gender see sex gene(s) 28–9 candidate 49, 52 conservation across species 58 expression 29, 60 mutations 30 products 28, 29 relationship with environment 33, 34 role in causation xxi–xxii, 32–4, 52 gene chips 53 gene–environment correlation 33, 34 adoption studies 44–5

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estimation 41–2 gene–environment interaction 33, 34 adoption studies 45 estimation 41–2 Generalised Anxiety Disorder (GAD) 137 gene therapy xxvi, 134 germline xxvi, 134, 141 safety 141 somatic 134 see also genetic interventions Gene Therapy Advisory Committee (GTAC) xxvi, 141 genetic counselling 16 genetic disorders causation 32–3 gene therapy 134 prenatal testing 148–9, 150 genetic drift 30 genetic factors in criminal behaviour 159–60 estimating influence 39–41 evidence for influence on behaviour xxiv family, twin and adoption studies 42–5 identifying 49–53 in intelligence 71–2 in personality 83–86 in sexual orientation 100–103 see also heritability genetic hitch-hiking 31 genetic information in education 183–4 in employment 177–83 in exculpation of criminal behaviour 160, 162–6, 171 guiding legal principles on use 176–7 in insurance 185–8 to predict antisocial behaviour 160, 168–71 in prediction of behaviour 35–6 in sentencing of offenders 160, 167–8 genetic interventions 134 in antisocial behaviour 167–8 effectiveness 140 individuality and 143 regulating provision 148 reversibility 142 safety 141 see also gene therapy genetics criminal behaviour 161–2 freedom and human dignity and 121–30 misunderstandings about 133 see also behavioural genetics; molecular genetics; quantitative genetics Genetic Screening: The Ethical Issues (Nuffield Council on Bioethics) 6, 175, 185 Genetics and Insurance Committee (GAIC) 185 genetic tests 5–6 accuracy 175 children 142–3, 170–1 compulsory 170 definition by insurers 185 in education 184 in employment 177–83 equality of access 145–6 individual choice and 142–3 in insurance 185–8 insurers’ Code of Practice 185 monitoring provision xxvii–xxix, 146–8 to predict antisocial behaviour xxxii, 170–1 predictive capacity 133, 175

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prenatal 148–50 provision xxvii purposes xix, 6 recommendations 147 genetic variation 29–31 genome-wide approaches 52 genotype 27 GlaxoSmithKline (formerly SmithKline Beecham) 137 Glover, Jonathan 17 Graham, Robert 16 Griggs v Duke Power Co. (1971) 178 Guidelines on Science and Health Communication xxii, 114 haemophilia 134 Hamer, Dean 102–3, 107 haploinsuffiency 61 Harvard Educational Review 20 health, IQ and 77 height 40–1, 92 herbal remedies xxix, 148 heritability 39–41 antisocial behaviour 91–4 sex differences 94 brain structure 75 broad-sense 40 common sense meaning 20, 39 generalisability of estimates 112 intelligence see intelligence (including IQ), heritability limitations of estimates 111–12 measuring 39–46 narrow-sense 40 personality traits 83–4 scientific meaning 20, 39 sexual orientation 101–2 versus genetic determination 40–1 see also quantitative genetics heterozygote 29–30 heterozygote advantage 30 high blood pressure 32 historical context xx–xxi, 13–22 homicide 93 homosexuality 7 in animals 103 attitudes to 99 evolution 106–7 legal status 99 linkage studies 50 public responses to genetic research 139 termination of pregnancy for 139, 153 see also sexual orientation homozygote 29–30 hormones, prenatal exposure 104 hostility 90 Human Fertilisation and Embryology Authority (HFEA) xxx, 149, 151 Human Genetics Advisory Council (HGAC) 6–7, 181 Human Genetics Commission (HGC) 7 monitoring genetic tests and interventions xxviii–xxix, 147–8 use of personal genetic data 175, 181–2, 185, 186 Human Rights Act 1998 (HRA) 180 humility, natural xxx–xxxi, 154–5 Huntington’s disease 19, 32–3, 124, 161 hypothalamus, interstitial nuclei of anterior (INAH) 104 Ibn Rushd (Averroes) 123 Ibn Sina (Avicenna) 123 identity, personal 121

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correlations between 70 history 18–19, 69 specific abilities measured 70–1 use in education 175 value 71 Islam 122–3

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IGF2R gene 74 impairment 179 Implications of Genetic Testing for Employment (Human Genetics Advisory Council) 181 impulsivity (sensation-seeking) 81, 160 legal responsibility 163, 164, 167 molecular genetics 84 quantitative genetics 83 incarnation 122 income protection insurance 186 individual differences 20–1 individuality, intervention and 143–5 Information Commissioner 181 inheritance see heritability innocence, presumption of 170 insanity, defence of 161, 165 Inside Information: Balancing Interests in the Use of Personal Genetic Data (Human Genetics Commission) 175 insulin 74 insulin-like growth factor II receptor (IGF2R) 74 insurance xxxiii, 175, 185–8 intelligence (including IQ) 8, 69–77 animal research 62–3 applications of current findings 112 aspects measured in IQ tests 70–1 assortative mating 149 definition and measurement 69–71 effects of general increase 143, 144 environmental influences 20, 41, 72 eugenic policies 17 future research directions 76–7 general cognitive ability (g) 52, 70, 76 heritability 71–3 debate from 1960s onwards 20–1 in first half of 20th century 18–20 scientific meaning 20 interventions to increase 135, 140 molecular genetics 73–6 prenatal selection for 153 quantitative genetics 71–3 secular increase (Flynn effect) 41, 69 selection and testing in education 183–4 tests see IQ tests ‘intermediate phenotype’ 34, 129 see also endophenotypes Int ernat ional Classif icat ion of Diseases (ICD), homosexualit y 99 internet xxix, 148 interstitial nuclei of anterior hypothalamus (INAH) 104 interventions (to change behavioural traits) xxv–xxvi, 134–5 access to xxvi–xxvii, 145–6 antisocial behaviour 167–8 choice 142–3 effectiveness 140 evaluating 140–5 individuality and 143–5 monitoring provision xxvii–xxix, 146–8 provision xxvii, 144–6 recommendations 148 reversibility 142 safety 140–1 therapy versus enhancement xxvi–xxvii, 144–5 see also environmental interventions; genetic interventions; medical interventions; prenatal selection Introversion 81, 82, 83 in vitro fertilisation (IVF) 148–9, 150 IQ (Intelligence Quotient) see intelligence IQ tests 69–71

Jensen, Arthur 20–1 Joseph Rowntree Charitable Trust 170 Judaism 122, 139 justice, eugenics and 18 juvenile delinquency see delinquency karma 123 Kinsey Scale of Sexual Orientation 99–100, 106 Klein Sexual Orientation Grid 100 Klinefelter’s syndrome (XYY males) 160–1 knock-out animals 58 law criminal 159–71 employment-related 177–81 learning, genetic enhancement 5, 59–60 legal principles, use of genetic information 176–7 legal responsibility xxxi–xxxii, 159–71 lesbianism see female homosexuality libertarianism xxvii, 146, 152–3 life insurance 186, 187 linkage disequilibrium 31, 50, 52 linkage studies 50–1, 52 Lombroso, Cesare 159 Luvox (fluvoxamine) 137 Maimonides 122 male homosexuality biological influences 104–5 molecular genetics 103 quantitative genetics 100, 101–2 see also sexual orientation males antisocial behaviour 94 criminal behaviour 161 ‘Man and his Future’ (Ciba Foundation) 15 Maternal and Infant Health Law (China) 17 media, reporting research results xxii, 113–14 medical examination, employees 177, 178 medical insurance 186 medical interventions 134, 135 in antisocial behaviour 167–8 choice 142 effectiveness 140 individuality and 143 monitoring provision xxix, 148 reversibility 142 safety 141 medicalisation antisocial behaviour 165 human behaviour xxv–xxvi, 135–9 Medical Research Council (MRC) 114 memory enhancement 144 mouse model with enhanced 5, 59–60 water maze task 62–3 Mental Deficiency Act, 1914 14 mental disorders 160 antisocial behaviour as 89 classification and diagnostic systems 99 concept of individuality 143

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dangerous severe personality disorder and 169 homosexuality as 99 legal responsibility 162, 163, 165 Mental Disorders and Genetics: The Ethical Context (Nuffield Council on Bioethics) 6 mental handicap 6 mental retardation 73 mental state, during criminal behaviour 162–3 methylphenidate (Ritalin) 137 microarrays 53 microsatellites 50 Ministry of Defence 181 Minnesota Multiphasic Personality Inventory (MMPI) 81 psychopathy scale 89 Mitchell, Gaynor 13 mitigating factors, sentencing of offenders 166, 171 molecular genetics xxi, 27, 49–53 antisocial behaviour 95, 96, 161–2 applications of current findings 112 association studies 51–2 bottom-up and top-down approaches 49–50 identifying alleles influencing behaviour 52 intelligence 73–6 lack of replicated findings 112 linkage studies 50–1 new larger-scale methods 52–3 personality traits 84 reporting research xxiii sexual orientation 102–3, 105 monoamine oxidase A (MAOA) gene 95, 112, 113, 161–2 ‘morally incompetent’ 14 motivations, self 122 mouse models 57–8 advantages 60–1 disadvantages 61–3 genetically-enhanced memory 5, 59–60 personality traits 85–6 violence 96 Muller, Hermann 16 Multidimensional Personality Questionnaire (MPQ) aggression scale 90, 94 multivariate genetic analysis 76 mutations 30 disease-causing 31 experimental induction 59 rates 76–7 narcolepsy 61 National Consumer Council xxix, 148 National Sickle Cell Anaemia Control Act, 1972 (US) 133 natural science 127–8 nature, interfering with 154 nature–nurture debate, intelligence 18, 20–1 Nazi Germany 6, 15, 17 negative emotionality 114 neo-Platonism 122–3 neuroplasticity 104 Neuroticism 81–2, 83 animal models 85, 86 applications of current research 112–13 quantitative genetics 82, 83, 85 neurotransmitters 84 see also dopamine; serotonin nirvana 123 Nobel Prize winners 16, 151 noradrenaline 84 normal behaviour xix–xx, 7, 31–2 other approaches to defining 7

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statistical approach 7, 31–2 normal capacities, enhancement xxvi–xxvii, 144–5 normal distribution curve 31, 32 normal variation, versus extremes 44, 45 novelty-seeking 83 DRD4 gene variant 51, 84 insurance issues 187 Noyes, John Humphrey 14 Nuffield Council on Bioethics xix, 6–7, 175, 185 occupational health and safety 182 occupational status, IQ scores and 71 offending see criminal behaviour Office of Fair Trading xxviii, xxix, 147, 148 Openness to Experience 81, 82, 83 oxytocin 60 PAH gene 124 pain, long-term 5, 60 parents consent by 170–1 relations with children xxx–xxxi, 154, 155, 156 Paxil (paroxetine) 137, 138 pedigree techniques 18–19 Perfectionist Community, Oneida, New York State 14 personality disorders 129–30 antisocial 89 dangerous severe 168–9 legal responsibility 163–4 psychopathic (psychopathy) 89, 163–4 personality traits 8, 81–6 animal research 85–6 antisocial 90, 92 applications of current findings 112–13 ‘Big Five’ 81–2 definition and measurement 81–3 future research directions 86 insurance issues 187 molecular genetics 84–5 and personal responsibility 129 quantitative genetics 83–4 testing in employment field 175 phenotype 27, 129 ‘intermediate’ 34, 129 see also endophenotypes phenylketonuria (PKU) 124 physiognomy, crime and 159 plants, selective breeding 14 pleiotropy 31, 86 Plomin, Robert 73, 76, 184 policy issues xxxii–xxxiii polygenic traits 19 polymorphisms 29 identifying significant 50 single nucleotide (SNP) 29, 30, 50, 52 population variation 32 environmental influences 41 gene–environment correlation and interaction 41–2 genetic influences 39–41 methods of studying 39–42 post-traumatic stress disorder 113, 161 poverty 166 prairie voles 60–1 pregnancy stress during 104–5 termination see termination of pregnancy pre implantation genetic diagnosis (PGD) xxix, 148–9, 150 for non-clinical reasons xxx–xxxi, 150–6

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quantitative genetics xxi, 27, 39–46 antisocial behaviour 91–4, 96 current applications 45 family, twin and adoption studies 42–5 intelligence 71–3 methods used 39–42 personality traits 83–4 reporting research xxiii sexual orientation 100–2 see also heritability quantitative trait loci (QTL) 50, 52 animal studies 62, 85–6 personality traits 85–6 race/ethnic origin discrimination 178–9 IQ scores and 20, 69 Race Relations Act, 1976 178–9 radiation-induced mutagenesis 59 rationalist position 126–7, 128, 130 rats, personality traits 85, 86 recessivity 30 recombination 31 reductionism 127 reincarnation 123 relatives see family religion 122–3, 179 Remaking Eden (Silver) 145–6

replication, association studies 52 Report of the Committee on the Ethics of Gene Therapy (Clothier Report) xxvi, 134, 141 reporting research on behavioural genetics xxii–xxiv, 113–14 Repository for Germinal Choice 16, 151 reproductive freedom right to xxx, 152–3 violations of 17–18 responsibility diminished xxxi, 164, 165–6 legal xxxi–xxxii, 159–71 personal 121–30 reversibility, of interventions 142 ribonucleic acid (RNA) 28, 29 Ritalin (methylphenidate) 137 RNA 28, 29 rodent models 85–6, 95–6 see also mouse models Ron’s Angels 151 Rose, Nikolas 159, 167 Rose, Steven 13 Rothman, Barbara Katz 133 Royal College of Psychiatrists 152 Royal Institution of Great Britain xxii, 114 Royal Society xxii, 114 Rutter antisocial scale 89

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public opinion 152 recommendations xxxi, 156 premenstrual syndrome 161 prenatal diagnosis (PND) xxix, 148, 150 public opinion 152 recommendations xxx, 152 prenatal environment sexual orientation and 104–5 twins 43 prenatal selection xxix–xxxi, 148–56 on non-clinical grounds xxx–xxxi, 150–6 arguments against 153–6 arguments for 152–3 public responses 152 recommendations 152, 156 technologies 148–50 prenatal testing 148–50 preventive detention 171 in severe personality disorder 168–9 primates, non-human 57–8 privacy 170, 171, 175, 180–1 private sector provision, interventions and tests xxvii, 144–6 procreative autonomy see reproductive freedom proteins 28, 29 Prozac (fluoxetine) 85 psychiatric disorders see mental disorders psychology in first half of 20th century 18–20 from 1960s onwards 20–1 psychopathic personality disorder (psychopathy) 89, 163–4 psychoticism 81, 84 Public Health Genetics Network 13 public responses genetic research into sexual orientation 139 prenatal selection xxx, 152 research into behavioural genetics 114–15 Working Party methods 195–203 public sector provision, interventions and tests xxvii, 144–6

safety of interventions 140–1 schizophrenia 165 selection 6 ‘adverse’ 186–7 in employment, education and insurance 175–88 prenatal see prenatal selection selective breeding 6, 13, 14 animal models 58–9 see also eugenics self, material 122–3 sensation-seeking see impulsivity sentencing of offenders xxxi, 160, 166–8, 171 serotonin 61–2, 84, 95, 112 serotonin transporter gene 84–5 sex differences genetic influences on homosexuality 106 heritability of antisocial behaviour 94 sex discrimination 178–9 indirect 178, 179 sex selection xxix, 149, 150–1 sexual orientation 8, 99–107 animal research 103 applications of current research 113 critique of evidence 105–6 employment discrimination law 179 evolutionary aspects 106–7 future research directions 107 molecular genetics 102–3 other biological influences 104–5 public responses to genetic research 139 quantitative genetics 100–2 trait measurement and definition 99–100, 105–6 see also homosexuality shyness 135, 136, 137–8 see also Generalised Anxiety Disorder (GAD), Social Anxiety Disorder (SAD) siblings pairs 50 selection of embryos as donors for xxx, 149 sickle cell disease 30, 133, 181 Silver, Lee 145–6

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Simon–Binet test 69 single-gene disorders 19, 33 single nucleotide polymorphisms (SNP) 29, 30, 50, 52 skin lightening 142 ‘smart mice’ 59–60, 113 SmithKline Beecham (now GlaxoSmithKline) 137 sociability 41 Social Anxiety Disorder (SAD) (shyness) 135, 136, 137–8 social disadvantage 41 socialisation 90 Social Issues Research Centre xxii, 114 social policies as interventions 135 misguided 133 socioeconomic status, IQ scores and 21, 71 Spearman, C. 70 sperm donors, selection 16, 151 sorting xxix, 149, 151 sporting ability 142, 143, 153 statism 18 sterilisation, compulsory 6, 15, 17 stigma 139, 171, 184 stirpiculture 14 stratification 51 stress, prenatal exposure 104–5 Sure Start scheme 135 susceptibility alleles 30 identifying 49–53 Sweden, eugenic practices 15 Switzerland, eugenic practices 15 syndromes, causing criminal behaviour 161 termination of pregnancy for fetal abnormalities 148, 149 for homosexuality 139, 153 for non-clinical reasons 152, 153 testosterone 105 tests see genetic tests therapy, versus enhancement xxvi–xxvii, 144–5 transgenic animals 58 transmission disequilibrium tests 51 twins dizygotic (DZ) 42–3 equal environments assumption 43 monozygotic (MZ) (identical) 42–3, 130 prenatal environments 43 twin studies 42–4, 45 intelligence 71–72 interpretation 43–4 methods 42–3 sexual orientation 101–2, 105 unfair dismissal 180 United Nations Educational, Scientific and Cultural Organization (UNESCO) xxvi, 141 United States (USA) employment-related law 178, 179 eugenic practices 15 Universal Declaration on the Human Genome and Human Rights (UNESCO) xxvi, 141, 176 Vallance, Grant 152 values, pluralism of 17 variance 32

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vasopressin 60 violence animal research 96 biological explanations 160–1 heritability 93–4 within relationships 94 see also aggression water maze test 62 Watson, James 18, 123, 139 Wellcome Trust 114 Wertz, Professor Dorothy C 152 X chromosome, Xq28 region 50, 102–3, 105, 107 XYY males 160–1

Genetic screening: ethical issues

Published December 1993 Human tissue: ethical and legal issues

Published April 1995 Animal-to-human transplants: the ethics of xenotransplantation

Published M arch 1996 M ental disorders and genetics: the ethical context

Published Sept ember 1998 Genetically modified crops: the ethical and social issues

Published M ay 1999 The ethics of clinical research in developing countries: a discussion paper

Published Oct ober 1999 Stem cell therapy: the ethical issues – a discussion paper

Published April 2000 The ethics of research related to healthcare in developing countries

Published April 2002 The ethics of patenting DNA: a discussion paper

Published July 2002

Published by Nuff ield Council on Bioet hics 28 Bedf ord Square London WC1B 3JS Telephone: 020 7681 9619 Fax: 020 7637 1712 Int ernet : w w w.nuff ieldbioet hics.org