Genetics of aggressive and violent behavior

This article develops the topic of the genetics of aggressive and violent behavior from three directions. Firstly, evidence from twin, family, and adoption studies will establish the case for the importance of genetically transmitted factors in the genesis of aggressivity from childhood through adulthood. Secondly, evidence from adoption studies will be presented to show that some environmental conditions interact with genetic factors in such a way as to suggest that the development of aggressivity requires that both genetic and environmental factors be present. Thirdly, additional and direct evidence of genetic factors in aggressivity is presented from the perspective of molecular genetics, where underlying biochemical mechanisms associated with aggressivity have been found to be caused by specific genes in animal models with confirmation of similar physiologic mechanisms in humans.