What makes a criminal? Scientists associate two genes with violent crime

Is a violent criminal born that way, or shaped by childhood experiences and circumstances? Delving into one of oldest questions in psychology, some scientists have suggested genes may contribute to roughly half of the influence - by affecting complex brain chemistry, for instance. But, until now, DNA clues to support this have been sketchy. Scientists in Europe and the United States on Tuesday fingered two genes which in a mutated form are found in a “substantially higher frequency” in violent offenders.

I think that we have found two genes which have the largest effect on aggressive behaviour, and that there are probably tens or hundreds other genes having smaller effects.

Jari Tiihonen, of the neuroscience department at Sweden’s Karolinska Institutet

A study of nearly 800 Finns jailed for both violent and non-violent crimes, and compared to the general population, found variants of two genes, called MAOA and CDH13, to be “associated with extremely violent behaviour”. The study was not designed to explain the impact of genetic variants and the authors believe there could be many other genes which play a role, directly or indirectly, in the molecular cascade.

Should these preliminary findings hold up, they would have significant implications for identifying potentially violent offenders at an earlier stage.

William Davies, a lecturer in behaviour genetics at Cardiff University

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