Genetics and Human Behaviour: the Ethical Context a Guide to the Report
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Genetics and human behaviour: the ethical context a guide to the Report Introduction Do we inherit our behaviour? Or The Nuffield Council on Bioethics does it depend on our upbringing? has published a Report, Genetics There is little doubt that genes and human behaviour: the ethical do have some influence on our context, which examines the ethical, personality. But how much? legal and social issues that Research to find out how our genes behavioural genetics raises. This influence our behaviour is complex summary sets out some of the and controversial. There are concerns arguments and recommendations both about the science itself and the which are discussed in more detail potential applications. in the Report. [Notes in square brackets throughout refer to chapters and paragraphs in the Report]. What is behavioural genetics? Research in the field of behavioural genetics aims to find out how genes influence our behaviour. Researchers are trying to identify particular genes, or groups of genes, that are associated with behavioural traits, and investigating the role of environmental factors. Scientific background The Report considers behavioural traits such What is normal? as intelligence, personality (including anxiety, novelty-seeking and shyness), antisocial behaviour We use a statistical definition of ‘normal’ to refer (including aggression and violent behaviour) and to the range of variation, usually about 95% of sexual orientation. The focus is on behaviour the population, which does not contain anyone within the normal range of variation, rather than with clinical disorders or diseases. This use of diseases or disorders. ‘normal’ does not imply any value judgement about different forms of behaviour. Is there a ‘gene for X’? Our focus is on traits that are continuously distributed. These traits are not either present or Some diseases are caused by changes to a single absent, but are found in everyone to some gene, such as cystic fibrosis and Huntington’s greater or lesser extent. It is likely that disease. But many diseases are not most behaviours lie on a continuous spectrum straightforward. For example, heart disease and [paras 3.7-3.8]. diabetes are likely to be affected by many genes, and the environment may also play a role. The relationship between genes and behaviour is even How is the research conducted? more complex. It is widely agreed that genes do I Quantitative genetics: researchers compare have some influence on behaviour but it is likely different groups of people, for example, identical that many genes are involved in influencing and non-identical twins, brothers and sisters, behaviours. Environmental factors will also have families and adopted children. These studies use an effect [Chapter 3]. statistical methods to determine the relative There are several reasons why it is so difficult to find contribution of genetic and environmental which genes have an effect on behavioural traits: factors in influencing behaviour [Chapter 4]. I Molecular genetics: researchers aim to identify I more than one gene may contribute to a trait, individual genes, and to understand how with many genes each having a small effect; different gene variants might influence I a gene may affect more than one trait (for variation in behaviour [Chapter 5]. example in mice, memory and sensitivity to pain I Animal models: researchers use animals to try to have been found to be linked); examine the effects of particular genes on I the action of a gene depends on the presence behaviour. Research is mainly focused on mice of other genes; and rats, but also primates, birds, fish and fruit flies [Chapter 6]. I environmental factors may contribute to a trait; I genes and the environment interact together in What are the findings so far? different ways; and I genes do not have a continuous effect The Report describes the scientific evidence so far, throughout our bodies or for all of our lives. with reviews of research on intelligence, personality, antisocial behaviour and sexual It is unlikely that variation in just one gene orientation [Chapters 7-10]. Behavioural genetics contributes to a behavioural trait. The term a is still a highly speculative area of research. A few ‘gene for X’ is very misleading and does not genetic links have been suggested but, despite convey the complexity of genetic factors. Nor the newspaper headings, to date no individual should we overestimate the predictive power of gene has been shown conclusively to influence genes. The effects of genes are not inevitable. antisocial behaviour, anxiety or intelligence in the Genes, like environmental factors, probably just normal range, or sexual orientation. make a behaviour more or less likely to occur. They are part of the cause, but not the only cause. 2 Concerns about behavioural genetics Concerns about applications Fear of eugenics Misuse of information e.g. [Chapter 2] for employment, insurance or education [Chapter 15] Changing and selecting traits Is the science robust? [Chapter 12] [Chapter 11] Discrimination and Behavioural stigma [Chapter 13] Ignoring research genetics in other areas, ‘Medicalisation’ including social [Chapter 13] and environmental factors [Chapter 11] Impact on legal system [Chapter 14] Impact on our understanding of free will [Chapter 12] Concerns about the research Will behavioural genetics research lead to Is the science robust? eugenic policies? Concerns about research in the field of Research in behavioural genetics takes place in the behavioural genetics include: shadow of eugenic practices. Eugenics, literally I the difficulty of defining and measuring meaning ‘well born’, is the idea of improving behaviours; humanity using scientific methods, for example, by selective breeding. But the use of negative I the dangers of misinterpreting or misapplying eugenics was a central aspect of some of the worst statistical estimates of heritability; atrocities in recent history. In the US, Europe and I the lack of replicated findings; and elsewhere, hundreds of thousands of people were segregated and sterilised. In Nazi Germany, I difficulties in predicting how behaviour ‘euthanasia’ programmes attempted to eliminate develops because of the complex interaction entire groups of people. These policies have been between genes and the environment. widely, and rightly, condemned. The Report outlines the history of the eugenics movement, its Despite these concerns, we think that it is both impact on research into human behaviour, and the theoretically and practically possible to identify lessons that may be learnt [Chapter 2]. genes that influence behaviour, and to understand something about the way they work Despite its history, contemporary research in [Chapter 11]. behavioural genetics is not necessarily eugenic. We conclude that it is important to understand There are currently no practical applications and learn from the past, in order to prevent of research in the genetics of behaviour within similar abuses happening in the future. the normal range. But it is not too soon to Historical and philosophical studies of eugenic examine ethical and social issues raised by practices and policies should be encouraged potential developments. [para 2.20]. 3 Changing and selecting traits Changing traits How should we evaluate interventions to change behaviours? If we can identify which genes influence behaviour, it may be possible to use this information to There are five questions to consider when modify people’s behaviour, by developing a range deciding whether it is acceptable to try to of approaches or treatment [Chapter 13]. change a behavioural trait [paras 13.26-13.43]. These apply to all types of intervention: How might behavioural traits be changed? I Will it be effective? I Genetic interventions: gene therapy – the I Is it safe? repair or replacement of a gene, or the introduction of a working gene along aside a I Is it reversible? faulty one – could be used to alter behaviour. I Who makes the choice? I Medical interventions: using medicines to alter I What are the implications for individuality? behaviour, for example, anti-depressant drugs or drugs to reduce shyness or enhance memory. Should gene therapy be allowed? I Environmental interventions: using social policies, such as changes in diet, education or In the future, gene therapy could be used to alter parental care. This type of approach is used genes that influence behaviour. There are two already, for example, improving a child’s diet types of gene therapy: somatic gene therapy and standard of living can improve his or her which modifies the DNA in the body, usually in intelligence. targeted cells, and germline gene therapy where the reproductive cells are altered and the changes It is not obvious which of these approaches will be are transmitted to future generations. most effective in altering behaviour, and each case should be considered separately. Although we Behavioural variation within the normal range often assume that environmental approaches will is not life-threatening and does not have be safe and reversible, this is not necessarily true serious implications for health. We consider [paras 13.7-13.12]. that gene therapy to change normal behavioural traits is currently too risky, but we recommend that GTAC (Gene Therapy Advisory Medicalisation Committee) should develop guidelines for research into gene therapy for such traits. We One concern is that research in behavioural do not think that germline gene therapy for genetics might exacerbate the trend towards behavioural traits within the normal range can ‘medicalisation’, where behaviour previously be justified [paras 13.31-13.32]. thought to be normal is increasingly thought of as a disorder. This development could lead Is an intervention accessible to everyone? to people being put under increasing commercial and social pressure to use Who should be able to make use of genetic tests medical interventions, when they are not and interventions? Who should pay the costs? always necessary. It may also lead to reduced There are concerns that only wealthy people tolerance of different behavioural traits.