Exploring the genetic basis of violence: The impact of Y and X chromosomes

Violence is a pressing global concern, causing more than 475 000 deaths annually and disproportionately affecting women and children. While environmental, genetic, and epigenetic factors contribute to violent behavior, this article focuses on the genetic aspect, particularly the roles of the X and Y chromosomes. The monoamino oxidase A () gene influences neurotransmitter catabolism and is located on the X chromosome. Polymorphisms, such as tandem repeat variants associated with low transcriptional activity, have been linked to aggression, particularly in men, as X chromosome inactivation complicates studies in women. Other variants, including single-nucleotide polymorphisms, have also been associated with violent behavior. Additionally, individuals with fragile X syndrome often exhibit increased aggression patterns. The Y chromosome's sex-determining region Y gene () plays a pivotal role in male sexual development and behavior. Besides directing testicular formation, is expressed in other tissues, influencing violence by modulating catecholamine release and inhibiting the monoamio oxidasa A. Evolutionary hypotheses suggest that may have adapted to promote male aggression for survival. Despite evidence linking the X and Y chromosomes to violence, conflicting findings highlight the need for further research to fully understand their roles in aggressive behavior. This article focuses on the genetic component, specifically analyzing the bibliographic evidence associating Y and X chromosome genetics to violent behavior.