Nature Versus Nurture - Implications in Law

Implications in Law

Recently, the nature versus nurture debate has entered the realm of law and criminal defense. In some cases, lawyers for violent offenders have begun to argue that an individual’s genes, rather than their rational decision-making processes, can cause criminal activity. Early attempts to employ a genetic defense were concerned with XYY syndrome – a genetic abnormality in which men have a second Y chromosome. However, several critiques argue that XYY individuals are not predisposed to aggression or violence, discrediting the theory as a plausible criminal defense.

Evidence that supports the genetic defense stems includes H.G. Brunner's 1993 discovery of what is now known as Brunner Syndrome, and a series of studies on mice. Proponents of the defense suggest that individuals cannot be held accountable for their genes, and as a result, should not be held responsible for their dispositions and resulting actions. If a single gene mutation is the reason for aggressive behaviour, there is a possibility that aggressive offenders would have a genetic excuse for their crimes. Genetic determinism has been debated for its plausibility of use in the judicial system for some time, yet "the use of a 'genetic defense' in the courtroom is a fairly new phenomenon." In the United States, use of genetics in court defense has been used and successful in reducing sentencing for violent offenders, for "certain predispositions may reduce the blameworthiness of the offender."

Canadian Judge Justice McLachlin denotes, "I can find no support in criminal theory for the conclusion that protection of the morally innocent requires a general consideration of individual excusing conditions. The principle comes into play only at the point where the person is shown to lack the capacity to appreciate the nature and quality or consequences of his or her acts."

Several mitigating factors already shape the purposes and principles of sentencing in relation to genetics such as impairment of judgment and a disadvantaged background. A 'genetic predisposition to violence' could fall similarly under the same statute laws 718c in the USA as a mitigating factor in crime if the science behind genetic determinants can be found conclusive. However, Duke University researcher Laura Baker disagrees, as "although genes may increase the propensity for criminality, for example, they do not determine it."