became the new reference model when evaluating the impact of the chosen candidate SNP. Model 4 contained all predictors from Model 3 plus the number of T alleles at rs279871 (additive genetic model). The likelihood of initiating drinking was 28% higher for each additional copy of the T allele (aHR = 1.28 fold, p = 0.01). Model 5 contained all predictors from Model 3 plus the presence of a homozygous TT genotype (recessive genetic model for the high-risk T allele). The likelihood of initiating drinking was 54% higher for those with the TT genotype (aHR = 1.54-fold, p < 0.001). The effects of predictors and covariates common to Models 3–5 were very similar in magnitude. LRT between nested models concluded that Model 3 should be rejected in favor of both Model 4 (χ2[df = 1] = 6.63, p = 0.001) and Model 5 (χ2[df = 1] = 11.07, p < 0.001). Model fit statistics of AIC and SBC were both lower for Model 5 compared to Model 4, suggesting that Model 5 was the best overall model.
