Two American studies comparing identical twins, who share the same genes, with non-identical twins, have supported the contentious suggestion that some criminals may be born, not made. However, other scientists and criminologists have criticised the agenda and membership of the closed meeting this week at the Ciba Foundation.
The row has now reached the European Parliament. Yesterday, Hiltrud Breyer, a German MEP who has campaigned against the patenting of human genes, warned that ideas from the meeting "deny the social character of violence: the unemployed, the poor and the homeless would be the target of a new branch of pharmaceutical intervention. Crime and poverty would no longer be considered as the social and economic problems that they are but as curable illnesses caused by personal biological make-up."
One of the speakers at the meeting, Professor Judy Silberg from the department of human genetics at Virginia Commonwealth University, said in an interview that children who exhibit "attention deficit disorder" at six may be saved from a career of criminality later if they are put on a course of therapeutic drugs.
Professor Silberg has studied 1,412 pairs of twins and their parents in an attempt to separate a significant inherited component to criminal behaviour from that due to environment and upbringing. The twins were all Caucasians aged eight to 16.
For some children she found juvenile delinquency was just a phase they grew out of. It appeared to have no genetic basis but to be strongly influenced by peer-group pressure and the environment in which they lived.
However, Professor Silberg believes she has identified a more numerous group of twins who have "co-morbidity of attention-deficit disorder [as children] with adolescent conduct disorder" - children who misbehave at school and grow up to be delinquents. Professor Silberg believes genetic factors govern the behaviour of these children.
A separate study of 3,200 pairs of male twins who served in the United States armed forces between 1965 and 1975, during the Vietnam era, has revealed similar differences between criminality persisting into adulthood, which appears to be genetically linked, and criminality which adolescents grow out of.
But this study, by Dr Michael Lyons, a psychologist from Boston University, showed that "violent behaviour is less influenced by genetic factors". Genetics are more important for petty criminality, such as theft, selling drugs and pimping.
This finding appears to run counter to research on animal behaviour which has revealed that biochemical imbalances can render laboratory mice highly aggressive. But Dr Lyons believes that "it's tricky to analogise between aggression in non humans and human violence. Aggression may make you a good ... race car driver. Lawyers can be pretty aggressive too".Reuse content