from this report comes from the younger cohort’s third assessment (ages: males: M =18.04, SD= 0.66; females: M=18.28, SD = 0.71) as a comprehensive alcohol use assessment was conducted with this cohort for the first time. Our aim was to recruit these participants during their senior year of high school. Zygosity was determined using information from the parents, evaluation by the staff of physical similarity, physical measurements (e.g., fingerprint ridge count), and, when needed, the use of DNA markers. More information about the characteristics of this cohort of twins can be found elsewhere (Blazei, Iacono, & McGue, 2008; Herndon & Iacono, 2005; Johnson, McGue, & Iacono, 2005; McGue, Iacono, Legrand, Malone, & Elkins, 2001).
