'Criminal gene': Does it exist?

University of Canterbury academic Dr Debra Wilson said her new book -- Genetics, Crime and Justice -- would examine the ethical and legal issues genetic research raises. Photo / iStock

Are criminals born or made? The author of a new book says genetics and neuroscience will change the justice system, as questions of a "criminal gene" increasingly emerge in legal cases.

University of Canterbury academic Dr Debra Wilson said her new book -- Genetics, Crime and Justice -- would examine the ethical and legal issues genetic research raises.

High-profile studies of interest to the "criminal gene" debate have already been carried out in countries including New Zealand.

Raising an issue with potentially far-reaching consequences for concepts of free will and criminal responsibility, Dr Wilson said the genetics defence had already been used in more than 200 cases in America and in Europe.

She said the defence raised questions around verdicts, jury decisions, sentencing and other issues for societies worldwide.

Wellington criminologist Dr Michael Roguski said the "jury was still out" on whether a criminal gene existed.

Dr Roguski said ideas of a criminal gene could quickly snowball into undesirable or oppressive activities such as racial profiling and eugenics.

He also said the idea of a criminal gene could be a way for society to absolve itself of responsibility for the conditions that exacerbated crime.

"It's very easy for society to say that the deficit's in the individual, rather than understanding the context within the wider society and the social pressures of say, unemployment, or childhood abuse. I lean more towards nurture, not nature."

In 2002, Dr Avshalom Caspi and colleagues published a paper examining the role of the monoamine oxidase A gene (MAOA) in the development of antisocial behaviours.

The researchers tracked people born in Dunedin in the early 1970s.

Their findings showed MAOA modified associations between childhood abuse and antisocial behaviour, and people with the low-activity MAOA variant were more responsive to the effects of maltreatment than the high-activity group.

Low activity of the gene meant neurotransmitters serotonin, dopamine, and norepinephrine were not properly metabolised.

Last year, a study published in Molecular Psychiatry said at least 5-10 per cent of all violent crime in Finland could be attributed to individuals with the MAOA and CDH13 genotypes.

Dr Wilson said New Zealanders would have to start talking about the consequences of research previously limited to the realms of science fiction.

"With the growing use of DNA databases, there are issues around privacy and individual rights that need to be considered."

She said society would have to ask if everyone should be tested, and how to respond if such a gene was identified.