(Nov. 11th, 2009) How can behavioural genetics save you from doing time? Based on gene expression analysis, an Italian court came to an interesting decision…
In 1876, Cesare Lombroso thought he was able to identify a criminal mind by facial features after observing male inmates in Italian prisons. According to him, a criminal had a slanting forehead, a flat nose and large jaws. That’s of course nonsense but hey, instead of your looks why not blame your own genes for your crimes?
It works, at least if you are tried in Italy. Nature recently reported that an Italian court cut down the sentence of a convicted murderer because of abnormalities in his gene expression. The man who stabbed and killed his victim over an insult already got less than the usual sentence because his lawyer claimed him to be “mentally ill”, the sentence was reduced even further when new tests, conducted by a molecular and a cognitive neuroscientist, found that besides irregularities observed in brain-imaging scans, five genes "associated" with violent behaviour were expressed at unusual levels, amongst them monoamine oxidase A (MAO-A).
MAO-A has been the focus of interest in behavioural genetics and courtrooms for some time because of its important function in the brain, the inactivation of monoaminergic neurotransmitters. MAO inhibitors used to be a common treatment option for depression but its direct association to aggressive behaviour could only be shown when there was a total lack of the enzyme (Brunner et al.) or when an individual with low enzyme activity was maltreated as a child (Caspi et al.). Furthermore, ethnicity also plays a role in the effectiveness of the MAO-A gene (Widom et al.).
Because of these rather non-supporting results, no court has ever ruled in favour of the genetically or, in this case, MAO-A-challenged person, even though a few lawyers have tried. However, the Italian neuroscientists responsible for the mitigation of sentence in the current case came to the conclusion that "some genes together with a particular environmental insult may predispose people to certain behaviour". This shaky statement was enough for the judge to let the man get off even more lightly and brought about questions whether genetic predisposition could be used as an excuse for misdeeds. One comment to the Nature news article gets to the heart of it, "Genes don't make you 'bad'. Genes make proteins!"
But next time you're caught committing a crime just claim, “It wasn't me, it was my genes!” It might just work.
Kathleen Gransalke