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Criminal genes: guilty as charged?

Posted by on October 14, 2013

Following on from her last blog post, Dr Claire Hastings discusses how our increasing knowledge of behavioural genetics might influence the criminal justice system, ahead of the Royal Institution debate entitled: “The good, the bad, and the genetically predetermined” 0n the 15th of October, during Biology Week 2013. Follow #rilive on Twitter from 19:00 on Tuesday 15th October.

Join the debate…

Criminal risk chromosome and hammer

Behavioural genetics is the study of the genes that have a role in determining behaviour. Establishing which genes are responsible for behaviour is complicated because more than one gene may affect a behavioural trait. However, if scientists are able to identify the contributing genes, they can perhaps provide early diagnosis and even develop treatments for behavioural disorders such as depression, obsessive compulsive disorder, eating disorders and many more. If you know you are more likely to suffer from these disorders then perhaps a change of lifestyle could minimise the risk of developing it.

The study of behaviour also covers antisocial or criminal activity. Several genetics factors have been identified to show an increased likelihood of criminal behaviour. Back in 1965, a study by Jacobs et al revealed that there is an increased percentage of men with an extra Y chromosome (XYY) in prison than in the general population. In fact, possessing a Y chromosome at all is a risk factor for criminal behaviour since the majority of prison inmates in the UK are men.

Chromosome pairs of females, males and men with XYY syndrome. Inheriting this extra Y chromosome cause those affected to experience an increased growth rate and severe acne as a teenager, resulting higher levels of testosterone. They are often more aggressive and have a slightly less than average IQ. XYY occurs in around 1 in 1000 males but most people who possess this extra chromosome have no idea as the appear within what is considered normal.

More recently, variants of genes involved in the processing of serotonin, noradrenaline and dopamine have also been implicated as a risk factor for criminal behaviour due to an increase in aggressive tendencies. As the field progresses many more genes involved in behaviour will be identified.

Research into this field poses interesting questions regarding to role of this new information in the criminal justice system. Where the advantages of research into clinical behavioural disorders are clear, it is less obvious how to use criminal behavioural genetics to benefit society.

There are three main topics of debate around behavioural genetics and the criminal justice system:
1) If someone is genetically predisposed to commit a crime, can they really be found guilty of it?
2) If found guilty, should criminals with genetic risk receive a more lenient sentence?
3) Should individuals be screened for criminally risky genes?

Before considering these points, it is important to consider whether genetics acts alone. As I discussed in my last blog post, genes are influenced by external factors such as the people and places we interact with, as well as happy and stressful life events.

Possessing a gene that predisposes criminal behaviour does not mean that person will inevitably become a criminal. People who experience happy, sheltered upbringings tend not to become criminals, irrespective of their genetic risk. If someone steals because they have little or no income, are they not a victim of their environment as much as a predisposed criminal is to their genes? If class and income had nothing to do with crime then ‘Made in Chelsea’ would be a very different TV show.

Therefore to answer point 1, unless the criminal justice system also holds parents, friends, the local community, society in general or acts of God to account, then genetics cannot be used to plead diminished responsibility. The individual must take responsibility for their own actions.

Taking into account a person’s home environment and background before sentencing (discussion point 2) is already common place in the criminal justice system, particularly in the case of young offenders. The penalty for murder may also be less for those whose commit a crime passionnel compared to premeditated crimes. A more aggressive or impulsive person may be more likely to commit crimes of passion so there is scope for a persons genetic make-up to be acknowledged during sentencing. There have been several cases in the USA where judges have taken this evidence into account.

Caution is necessary here. As I mentioned above, possessing a Y chromosome makes you more likely to commit a crime, so should women automatically get harsher punishments because testosterone isn’t clouding their judgement? I think not.

The third point is certainly more contentious. Once identified, developing a test to screen for genes that determine whether a person is likely to commit a crime or not is almost trivial undertaking for a scientist. But should this information be available? Children and adults have the right to genetic privacy to prevent stigma. However, if children are tested then they could receive additional support to meet their own personal needs.

The role of behavioural genetics in the criminal justice system is a fantastically interesting subject and this blog post only touches on aspects of the debate. I offer no conclusions at this point but if you are interested in learning more or if you have an opinion on any of the topics discussed above then come along to the Royal Institution on the 15th of October. Tickets are available now.

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