The moderation of genetic and shared-environmental influences on adolescent drinking by levels of parental drinking

Objective: Research has consistently shown an association between levels of parental drinking and adolescent alcohol use. Different mechanisms offered to explain this association include environmental mechanisms such as social learning and biological mechanisms such as genetic transmission. To integrate these perspectives, this study examines the moderation of environmental and genetic influences on adolescent alcohol use by parental drinking behaviors. Method: The data used were 1,833 pairs drawn from the National Longitudinal Study of Adolescent Health's monozygotic twins, dizygotic twins, full-sibling and half-sibling pairs. Analyses used Defries-Fulker (DF) models to estimate genetic and shared environmental influences and to evaluate the potential moderation of these influences by household parental drinking. Results: Full sample results revealed that genetic influences (h² = 0.46, p < .05) were significant but that shared environmental influences (c² = 0.10, p > .05) were not. Separate DF analyses for male, female and mixed-gender pairs found the magnitude of genetic and shared environmental influences on adolescents to be similar across male and female pairs. Results for mixed-gender pairs, however, were ambiguous. Extended DF models examining interactions between parental drinking and the expression of genetic and shared environmental influences found parental drinking was associated with a higher expression of genetic influences among male pairs but not among female or mixed-gender pairs. Conclusions: The main inferences to be drawn are that, at least for male adolescents, genetic influences on drinking appear to be potentiated by exposure to parental drinking.