Genes, environment, and individual differences in alcohol expectancies among female adolescents and young adults.

Alcohol expectancies are an important proximal causal risk factor in several models of the familial transmission of alcohol use, abuse, and dependence, yet the familial transmission of alcohol expectancies is not well understood. The purpose of this study was to examine the familial transmission of positive alcohol expectancies. Participants were 2,627 14- to 22-year-old female twins. Experiences shared by twins, rather than genetic factors, explained most of the familial similarity for positive alcohol expectancies, but an even larger proportion of the variation in positive alcohol expectancies was explained by nonfamilial factors. The extent to which the familial similarity for positive alcohol expectancies was moderated by age, race, drinking status, and the sharing of peer groups was also examined.