Data were drawn from the Collaborative Studies on Genetics of Alcoholism (COGA), a multi-site, large, multigenerational family study that aims to identify genetic influences on alcohol dependence and related psychiatric phenotypes (Begleiter et al., 1995). Probands were identified through alcohol treatment programs at seven U.S. sites and were invited to participate if they had a sufficiently large family (usually sibships of more than three with parents available) with two or more members affected by alcohol use disorder in the COGA catchment areas. Population-based comparison families were also recruited. Data collection for COGA started in 1991 when adults in the extended families were invited to complete the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA), a comprehensive interview that assesses demographic factors, alcohol use disorders, and a variety of psychiatric phenotypes (Bucholz et al., 1994). In 2004, COGA launched the Prospective Study that aims to examine how genetic risks unfold across development and in conjunction with the environment. Specifically, offspring in the extended families who were between ages 12–22 and had at least one parent who completed a SSAGA in the
