My genes made me do it

An article in the Washington Post discusses new uses of genetic testing in the courtroom that go far beyond standard forensic DNA profiling:

[...] defense attorneys are asking judges to admit test results suggesting that their clients have a genetic predisposition for violent or impulsive behavior, adding a potential "DNA defense" to a legal system that until now has held virtually everyone accountable for their actions except the insane or mentally retarded.

Some gene tests are even being touted for their capacity to help judges predict the likelihood that a convict, if released, will break the law again -- a measure of "future dangerousness" that raises questions about how far courts can go to abort crimes that have not yet been committed.

The article correctly notes that these tests are still very much at the fringes of science - behavioural genetics is a complex field, and the current associations are generally pretty weak. However, there's little doubt that many of the traits underlying a predisposition to criminal behaviour, such as a fondness for risk-taking or susceptibility to addiction, are substantially influenced by genetic factors, and it's only a matter of time before the major genes responsible are identified and characterised.

Although genetic testing will only ever allow for a probabilistic prediction of susceptibility to criminal behaviour (unlike the tortured psychics in Minority Report), society needs to prepare itself for the consequences of these findings. For instance, do "criminal genes" excuse someone from criminality, or do they simply provide an even better reason to lock such people away for the good of society? Should expensive family monitoring and support programs be targeted towards individuals who are genetically susceptible to antisocial behaviour in the presence of abuse or neglect? Given a limited budget, should rehabilitation programs focus on criminals who lack these susceptibility genes and may thus be less inclined to re-offend?

Update: The Genetic Genealogist has a great tangentially-related post on forensic genetics.

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