The core of this community sample was drawn from the Australian Twin Registry (ATR) volunteer twin panel, which was formed in 1978–79 and supported by the Australian National Health and Medical Research Council. Multiple collection phases of alcohol-related data ensued over the next 25 years, as described in detail in Hansell et al. (2008). Briefly, data were drawn from two phases of collection via mailed questionnaire and three subsequent phases of collection through telephone interview. The first mailed questionnaire survey (1988–1989) targeted twins born up to and including 1964 and their relatives, while the second (1989–1992) targeted twins born from 1964 through 1972 and their relatives. Follow-up telephone interviews, which were adapted from the Semi-Structured Assessment for the Genetics of Alcoholism (SSAGA, Bucholz et al., 1994), were conducted for both the older twin cohort (1992–1993) and the younger twin cohort (1996–2000). The third phase of telephone interviews (2001–2005) indexed smokers, drinkers, and controls from the older and younger cohorts. For 53% of our sample, self-reported ancestry for all grandparents was available. Ancestry was predominantly European with 93% having full European
