The use of genetic data to establish a physiological basis for violent or impulsive criminal behaviors is occurring more frequently in criminal trials. However, a new review finds that genetic evidence used in the courtroom is not likely to be effective in convincing judges and juries that the defendants are less culpable for their actions.
Evidence for a link between gene variants and criminal behavior has been tenuous. For example, low activity in the MAOA gene, found on the X chromosome, added to a history of childhood maltreatment, has been associated with an increased number of convictions for violent crime. However, the relationship between the gene’s activity, environmental factors, and criminal behavior is unclear.
One possible reason for its limited effectiveness may be that using genetic data arouses contradictory perceptions in the people hearing it in the courtroom.
It has also been argued that genetic explanations are not sufficient to decrease responsibility for behavior. The law requires that defendants must show limited rationality (e.g., due to insanity) or have a reason for reduced behavioral control (e.g., mental disability or young age) for the courts to reduce responsibility or shorten a sentence.
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