To understand the nature of the ALDH2 by age interaction, table 3 provides best-fitting model estimated mean alcohol use phenotype values for each genotype group at three ages (15, 18, and 22), which correspond approximately to the sample mean age at each assessment. For every phenotype, alcohol use occurred with very low incidence at early ages, but increased over the course of adolescence and early adulthood before leveling off or decreasing near the end of early adulthood (figures 1-3). Effect sizes for continuous outcomes, and odds ratio for the discrete outcome, show that, as we expected, the protective effect of the ALDH2*2 allele against all forms of alcohol use also increased with participant age (this trend may also be observed for each of the outcomes displayed on figures 1-3). For example, for the drinking index, the effect size for the estimated standardized mean difference between the ALDH2 groups grew from d = −.07 at age 15, to .22 at age 18 and .40 at age 22. Likewise, the predicted probabilities of alcohol abuse or dependence diagnosis showed the protective effect
