Behavioural genetics and risk of 'criminality'

'We're not arguing that genes made him do it but if violent behaviour is genetic then it is probably treatable'.

This comment by a US lawyer on behalf of his client (who was eventually executed for murder last year) sums up the hope invested in research into violent and antisocial behaviour (ASB). The legal team argued that Stephen Mobley should have genetic testing on the basis of evidence in the Dutch study by Brunner et al (1995) that found a link between lack of function of a gene called monoamine oxidase A (MAOA) and abnormal behaviours among men in successive generations of one family (1). A study based on a large New Zealand sample found a more complicated picture whereby there was a strong link between ASB  and low levels of MAOA among young men who had been abused as children (Caspi et al, 2002). Of course an abusive family is undesirable for any child, but the social factors correlated with maltreatment such as unemployment, poverty, single parent families and social class can only be tackled by expensive and difficult interventions at the community level. The discovery of a genetic influence could lead to pharmacological treatments, as the New Zealand study suggests, and these could target individuals and be relatively low cost.

An Institute of Public Policy Research (IPPR) report (2) has looked at issues raised by behavioural testing, from fears of discrimination and eugenics to individual responsibility. It concluded that behavioural genetic testing should be a matter of free choice and not be used to select individuals for State services. But is this realistic in the current political climate? There have been a series of measures in England and Wales to deal with ASB among the young, including ASB Orders (ASBOs) and baby ASBOs (for children under ten years old), child curfews and parenting orders. Children age 10 or older who are arrested can also be DNA swabbed and entered (for life) on the National DNA database even if they are never charged with a crime or are charged and subsequently acquitted. This database, with over three million samples, has already been used for research into ethnic profiling. Those who are served with ASBOs have been disproportionately male, urban and with low socio-economic status i.e. those most likely to be on the streets and available for policing. Evidence from self-report studies indicates that ASB of this type is actually widespread in all social classes and among both men and women. Street crime is of course only one form of anti-social behaviour:  environmental pollution, criminal negligence and fraud also cause social harm, injury, illness and distress.

If research and applications in the genetics of problem behaviours proceeds on the crime model then it will not be a matter of choice. If it proceeds on the health system model there would be more safeguards. But even if any genetic risk factors discovered are evenly spread though all classes and ethnic groups, any testing programme would begin with families or groups with higher levels of undesirable behaviour and risk factors. This could result in more reports on the lines of the study that linked MAOA variation to higher rates of aggression, violence and risk taking behaviour among the Maori in New Zealand.

There may be other fruitful lines of research but so far there are people with a genetic risk factor, people with environmental risk factors and people with both who do not go on to engage in violent or criminal behaviour. Interestingly, Stephen Mobley's family tree included both successful businessmen and men displaying abnormal violent ASB.  A predisposition for risk-taking and aggression can be channelled in different ways and the probabilities of going one way or another is related to the social and cultural environment in which the child is growing up. Perhaps some degree of ASB.  is an accepted part of the teenage years. The peak for offending is age 14, but most do not go on to be adult criminals. Research looking at the small group who display 'psychopathic' behaviour when very young could yield benefits, although even here researchers are careful to point out that environmental factors are important too (3). It seems that finding genetic factors in behaviour will not lead to the Holy Grail of a quick fix solution. The risk is that the research will stigmatise those in already stigmatised groups, like the Maori population, but fail to meet their needs.

'Criminal' Genes and Public Policy, CESAGen.