Sex and Cohort Differences in Genetic and Environmental Influences Underlying Childhood and Adolescent Antisocial Behavior

We examined sex and birth cohort differences in the magnitude of genetic and environmental influence on childhood and adolescent conduct problems in 293 same-sex and 100 opposite-sex adult twin pairs (aged 15-67 years) who were recruited on the basis of one or both twins' participation in a treatment program for Alcohol Use Disorder. The results suggested common genetic influences underlying alcohol abuse/dependence and antisocial behavior. In addition, cotwins of female probands reported more conduct problems than cotwins of male probands, suggesting that affected females both require and transmit a higher liability for antisocial behavior than do affected males. Despite sex differences for liability and -- to some extent -- in the relative magnitude of genetic and environmental influences, the specific genetic and environmental influences on conduct problems appeared to be the same in both sexes. Analyses ignoring birth cohort suggested that twin similarity for childhood and adolescent conduct problems was due mainly to genetic influences with minimal shared environmental influences. In contrast, birth cohort differences were found for the number of conduct problems reported, as well as for the genetic and shared environmental influences underlying these problems. Genetic influences were of greater magnitude in older cohorts, whereas shared environmental influences were of considerable magnitude only in younger cohorts. These findings suggest that secular trends in societal factors (e.g., increased poverty, community violence, and substance abuse in more recent generations) may have resulted in specific shared environmental influences that increase the similarity for antisocial behavior among family members differing in genetic liability.