For some, violent criminality may be written in their genes

In an apparent first, a study of Finnish convicts has identified genetic variations at two key sites on the genome that may distinguish extremely violent criminals from the rest of us. The two single nucleotide polymorphisms, or SNPs, that appear to predispose an individual to committing acts of repeated or extreme violence may account for as many as 10 percent of crimes, say the authors of the study.

Looking for a genetic basis for violent behavior makes looking for a needle in a haystack look easy. It also raises thorny questions about free will, criminal culpability and the perils of declaring a person dangerous based on biology rather than behavior.