in the bottom half of Fig. 1 (panels C and D) for African-Americans. In Fig. 1, an EA male with both MBFD and the high-risk TT genotype had the highest probability of starting drinking at any age; specifically, Model 5 predicts that 50% of such EA males will have had their first drink by an age of 14.2 years. The median age of first drink was delayed for an EA male with MBFD and without the high-risk TT genotype to just before their 15th birthday; to soon after their 15th birthday for an AA male with both MBFD and the high-risk TT genotype; to about 15.8 years for an EA male without MBFD and with the high-risk TT genotype; and to just after their 16th birthday for an AA male with MBFD and without the high-risk TT genotype. Three groups did not reach the 50% threshold for cumulative probability of drinking by age 17. These included EA males with neither MBFD nor the high-risk TT genotype (43%), AA males without MBFD but with the high-risk TT genotype (42%), and AA males with neither MBFD nor the high-risk genotype (29%). Changing the covariate of sex to female, while leaving age and
