Predisposition to criminality: Swedish adoption studies in retrospect.

The predisposition to criminality was studied in 913 women and 862 men from the Stockholm Adoption Study. Different genetic and environmental antecedents influenced the development of criminality, depending on whether or not there was associated alcohol abuse. Male alcoholic criminals often committed repeated violent offences, whereas non-alcoholic criminals characteristically committed a small number of petty property crimes. These non-alcoholic petty criminals more often had biological fathers with histories of petty crime but no excess of alcohol abuse. The risk of criminality in alcohol abusers was correlated with the severity of their own alcohol abuse, but not with criminality in their biological or adoptive parents. Most explained variation in petty crime was due to differences between the genetic predispositions of the adoptees, but substantial contributions were also made by postnatal environment, either alone or in combination with specific genetic subtypes. There was no overlap between the congenital antecedents of alcoholism and non-alcoholic criminality, but some postnatal variables were common to this kind of criminality and type 2 or male-limited alcoholism. Low social status alone was not sufficient to lead to petty criminality, but did increase risk in combination with specific types of genetic predisposition. Unstable preadoptive placement contributed to the risks of both petty criminality and male-limited alcoholism.