Interestingly, we found that the pathogenic gene-by-environment interaction effect decayed over time. Heavy episodic drinking was similar across all conditions by age 23, and by age 25, the effect was reversed. At age 25, we found that married individuals with higher polygenic scores had lower heavy episodic drinking compared to those with lower polygenic scores. In contrast, at age 25 heavy episodic drinking was similar among all unmarried participants, regardless of genetic risk. Our finding adds developmental nuance to the extant literature on gene-by-environment interaction effects for alcohol outcomes, in that it further suggests that marriage is not a uniformly protective environment. Moreover, it underscores the importance of examining intersecting risk and protective factors, with particular consideration of the potential ramifications of developmentally off-time events (e.g., being at greater genetic risk and marrying young).
