Fabio Ruini’s blog

Whenever research is published revealing a link between genes and criminal behaviour, a wave of controversy follows. Some critics argue the research will lead to a new eugenics movement with offenders subject to forced sterilization, or those with the ‘wrong genes’ locked up pre-emptively. Others fear that connecting genes to crimes will lead to lighter sentences, since it de-emphasizes personal responsibility.

Until recently, these were philosophical debates because genetic research has rarely factored into sentencing decisions – and when it has, it has often been dismissed. That all changed when an Italian court decided to shave one year off a nine-year sentence handed to convicted murderer, Abdelmalek Bayout, who was found to have a small handful of genes previously linked to violence.

The court’s decision to reduce Bayout’s sentence is questionable. Criminal behaviour is highly complex, the result of many genes and many environmental factors. Hundreds or even thousands of genes influence the likelihood that someone will offend and each of these has very small effects. So when a single gene, or only a small number of genes, is examined in isolation, it can only account for a small part of the reason why someone would commit a crime. In the Bayout case, just five genes were used to justify the reduction in his sentence.

With criminal behaviour, or virtually any behaviour, genes are not fatalistic nor are they deterministic – they simply increase or decrease the odds of someone committing a criminal act. The vast majority of people with Bayout’s genetic variants never engage in crime, much less kill another human being. Other factors, including environmental ones, play a role.

With one of the genes identified in the Bayout case, MAOA, previous research has found it only tends to have strong effects on crime and violence in people who were exposed to high levels of stress, abus and neglect in childhood. So whether the MAOA gene was indeed a mitigating factor in Bayout’s case would depend, in large part, on his childhood. The court appears to have glossed over this.

During the past five years, there have been at least 200cases in the US and 20 in Britain where lawyears have tried to use genes as mitigating factors. And this number is likely to increase rapidly because research tying genes to criminal behaviour is growing at an incredible pace.

So, should an individual’s genes determine their punishment? At this point, we probably do not know enough about how genes influence criminal behaviour to be basing sentencing decisions on whether a defendant possess a single gene or even a number of different genes. But if genetic research does find its way into the legal system on a routine basis, it is imperative that courtroom actors are aware that the path from a gene to crime is a long one that involves environmental, biological and genetic factors that are mutually interdependent on each other.

Around about now, I’ll be chucking in the towel on my post-Christmas diet. And if it’s anything like past years, there will be much celebration among friend and family alike. Not because of my new, slimline appearance – fat chance of that – but because I’ll no longer be in a seething temper. Like any human being, I object to not being allowed to eat stuff I like. But there’s something else: eating a lot of some foods I am allowed to eat seems to do my head in too.

I first noticed this a few years back when I went on a low-carb diet. This seemed great, as I could forget about calorie counting and just swap high-carb food like bread and potatoes for loads of lovely protein-rich stuff like cheese and meat. And as a way of losing weight, it worked a treat: I lost several kilograms in a fortnight. But I had to give it up – partly out of boredom, but mainly because I was in danger of murdering passers-by. For some reason, all that protein put me in a towering rage. Once I stopped, I went back to being merely tetchy.

Ever since, I’ve been on the look-out for evidence that diet causes bad behaviour. When celebrity chef Jamie Oliver did his better school dinners campaign, I was struck by how the teachers reported that their kids were much better behaved once they switched to a healthier diet. But what really impressed me was a study carried out at a young offenders’ institutions in Aylesbury. Inmates were given food supplements to see what effect it had on their behaviour, and the researchers found it cut violent incidents by 35 per cent.

One might have thought the prison authorities would jump at this recipe for improving life in Britain’s jails. After all, food supplements are cheaper than paying NHS doctors to take knives out of people’s eye-sockets. Yet the Government refused to accept the findings, or fund any further research – apparently for fear of appearing ‘soft’ on criminals.

Fortunately, the Wellcome Trust charity has decided it doesn’t mind annoying the Daily Mail, and has stumped up £1.5 million to fund a study of the effects of diet in three UK prisons. The project involves over 1,000 inmates and is due to run for another two years, but findings from studies in other countries suggest it’s likely to confirm that nutrion can have a profound effect. Research has linked traits like impulsivity and aggression to low levels of zinc, calcium and omega-3.

And it’s not just behaviour that’s affected. Studies of disadvantaged young people have found they’ve typically got low intakes of dietary iodine, iron and selenium – all of which are linked to poor cognitive functioning. Improving nutrition could therefore do more than just make prisons less violent: it might also help inmates stay out of trouble once released (as long as they stay off the junk food when they get home). If there’s one thing that leads to a life of crime, it’s an inability to hold down a job – and that’s hard to do when your brain isn’t working too well.