The Influence of Spousal Genotype on Alcohol Problems in Marriage

The conventional understanding of how genetic factors impact risk for alcohol use disorder (AUD) typically focuses on how one’s own genetic predispositions influence the likelihood of experiencing clinically significant problems with alcohol (direct genetic effects). Yet, in close relationships like marriage, a spouse’s genotype may function as part of the target individual’s environment through its influence on spousal behaviors and experiences, termed social genetic effect. We examined social genetic effects on AUD in 660 opposite-sex spousal dyads from the Collaborative Study on the Genetics of Alcoholism, restricting analyses to individuals who were genetically similar to European reference panels. Measured and latent indicators of genetic risk included polygenic scores of problematic alcohol use (PGSPAU) and parental history of AUD (PHAUD), respectively. The outcome was DSM-5 alcohol use disorder criteria count (AUDsx) during marriage. After accounting for direct genetic effects (i.e., the influence of one’s own genetic predispositions) and the correlations between partners’ genetic predispositions, we found that having a spouse with a higher PGSPAU was associated with greater AUDsx (B = .08, 95%CI [0.035, 0.132]). This social genetic effect was robust after controlling for both partners’ educational attainment. Spousal PHAUD was not associated with AUDsx. Exploratory analyses indicated that the social genetic effect of partner PGSPAU was stronger for males. Findings highlight the potential importance of social genetic effects for understanding the pathways from genotype to alcohol use disorder, and the need for further investigation of latent measures of genetic predispositions in studies of social genetic effects.