ABSTRACT
Although career criminality has been referred to as the holy grail of criminological research, virtually all the literature centers on its sociological and psychological characteristics. The paucity of biological research is unfortunate given the empirical strength of the effects of genetic and biological factors on antisocial and aggressive behavior. For instance, Walters (1992:604) conducted a meta-analysis of 38 family, twin, and adoption studies on crime and found a consistent and statistically significant association between various indices of heredity and crime. He concluded: “With a mean unweighted effect size of .25, median effect size of .17, and mean weighted effect size of .09, there would appear to be guarded optimism for a genetic interpretation of certain facets of criminal behavior.” Since that analysis, “guarded optimism” about the genetic bases of serious antisocial behavior has become significantly more substantial. Moffitt’s (2003:54-55) review of the literature indicated that approximately 60 percent of variation in aggression and approximately 40 percent of variation in delinquency is heritable.
