Data from adoptive families suggest that exposure to parent smoking represents an environmental risk factor for the lifetime use of tobacco and marijuana in adolescent offspring. When contrasted with data from biologically related families, however, the findings indicate that the effect of exposure to parent smoking is both larger and more diverse when adolescents and their parents share a common genetic endowment. Thus, smoking parents may provide an environment that increases their offspring's risk for tobacco and marijuana use, and non-adoptive parents may also transmit genes that increase their offspring's liability for disinhibited behavior, including substance use, disruptive behavior disorders, delinquency, antisocial attitudes, aggressive orientation, and preference for risk taking.
