Samples were ascertained from a pool of approximately 11,700 Australian families identified through diagnostic interview surveys of two cohorts of like-sex and unlike-sex twin pairs from a volunteer Australian twin panel (cohort 1, born 1895–1964 [N=5995 interviewed twins (4)], but for the purposes of this study mostly born 1940–1964; and cohort 2, born 1964–1971 [N=6257 twins:(26)], as well as through an interview survey of the spouses/partners of the former cohort (N=3846,(27)). Index cases from these families, their full siblings and parents were recruited for three coordinated studies: (i) the NAG (Nicotine Addiction Genetics) Study (28) which ascertained heavy smoking index cases; (ii) the OZALC-EDAC study, which ascertained index cases with a history of alcohol dependence or scoring above the 85th centile for heaviness of drinking factor score (operationalized as in(14)); (iii) the OZALC-BIGSIB study, which ascertained large sibships (4–14 full siblings), regardless of sibling phenotypic values. Additional cases and controls were recruited from Cohort 1 participants, and additional Cohort 2 participants, who did not complete the new interview protocol but had comparable alcohol use/dependence assessments. Finally an unassessed population control
