"Warriror gene" BTFO

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Violent crime is a major issue that affects the quality of life even in stable and wealthy societies. In industrialized countries, the majority of all violent crime is committed by a relatively small group of antisocial recidivistic offenders,1,2 and more than 50% of severe antisocial behavior is attributable to genetic factors.3 The classic study by Mednick et al.,4 reported a significant correlation between adoptees and their biological parents for property crimes, but not for violent crimes. However, a recent study using an enormous Swedish nationwide adoption database with a long follow-up period found convincing evidence that the criminal records of biological parents predicted both violent and non-violent criminality among their adopted away children.5 Two decades ago, it was observed that a rare mutation leading to a complete deficiency of monoamine oxidase A (MAOA) was associated with impulsive and aggressive behavior in a Dutch kindred.6 Thus far, only two studies have reported an association between a specific gene and criminal violent offending.7,8 In the study by Caspi et al.,7 55 (12%) of the boys who were studied had a combination of the low-activity MAOA promoter genotype and childhood maltreatment, which accounted for 44% of the violent convictions in their cohort.7 Although this finding has not been replicated, and the majority of violent convictions in this cohort were not severe, such as homicide or attempted homicide, this MAOA variant has become widely called as a ‘warrior gene’.