As noted above, this study was conducted in a national sample of adults. Research has shown that, while genetic factors account for 28% of the variance in alcohol dependence in adolescence, in young adulthood (age 30 to 32) effects of genetic factors nearly double (58%) and remain above 50% into adulthood (van Beek, Kendler, & de Moor, 2012). As such, in post-hoc analyses we checked for 3-way interactions (such as age X FH X outlet density) but these were not statistically significant when assessed several ways, including using the categorical age variable included in the adjusted models, using a continuous age variable, and using a dichotomous indicator separating respondents under age 40 from older respondents. It would be valuable for future studies to fully examine differences in FH effects and area-level social control on alcohol outcomes across the lifespan, including data from adolescents to older adults.
