It is possible that genetics could soon play an important role in the criminal justice system.  It is likely that genetics is responsible for contributing to many personality and behavioral traits.  However, studies confirm that environment accounts for many aspects of behavior regarding criminality and there is currently no evidence that an individual's genetic composition makes one more predisposed to criminal deviance.

Interestingly, one Dutch family studied tends to refute this argument.  There appears to be a strong genetic influence as compared to environmental factors on certain traits regarding aggression in the family.  Although this differs from the norm, it is arguable that in rare cases such as these, there is a genetic defect which causes a predisposition to criminal behavior.

Therefore, it could be argued that a defendant's criminal behavior was genetically determined by factors uncontrollable by the individual.  Lacking control over his or her actions, said defendant might not be held accountable for his/her crimes.  This would create an entirely new defense that could be dangerously abused, leading to a breakdown of criminal liability.

There are even questions as to whether genetics can be accurately used to justify a ruling of "not guilty".  It is interesting to ponder whether genetics will soon be relevant in sentencing.  And what should happen to those whose genetic defenses are successful, but remain a threat to themselves or others?  Is it possible to make a genetic defense without challenging the idea of criminal responsibility?