Adolescent alcohol use was measured at age 14 using an item that asked subjects to report how frequently they drink alcohol, with 4 response options (once a week or more; about 1 to 2 times a month; less often than once a month; never, I don’t drink alcohol). A total of 1,432 same-sex twin pairs (373 female MZ, 340 male MZ, 341 female DZ, and 378 male DZ) responded to the item and were used in analyses. For alcohol use frequency, 66% of the sample reported that they had never used alcohol, 19% reported drinking less often than once a month, 11% reported using alcohol about 1 or 2 times per month, and 3% reported using alcohol once per week or more. After adjusting for the familial clustering in the data, girls are slightly more likely to report alcohol use than boys at this early age [F(2.77, 3965.03) = 3.39, p = 0.02], as has been discussed previously in this sample (Rose et al., 2001a).
