Genes, Roommates, and Residence Halls: A Multidimensional Study of the Role of Peer Drinking on College Students’ Alcohol Use

Peer drinking is one of the most robust predictors of college students’ alcohol use and can moderate students’ genetic risk for alcohol use. Peer effect research generally suffers from 2 problems: selection into peer groups and relying more on perceptions of peer alcohol use than peers’ self‐report. The goal of the present study was to overcome those limitations by capitalizing on a genetically informed sample of randomly assigned college roommates to examine multiple dimensions of peer influence and the interplay between peer effects and genetic predisposition on alcohol use, in the form of polygenic scores. We used a subsample (n =755) of participants from a university‐wide, longitudinal study at a large, diverse, urban university. Participants reported their own alcohol use during fall and spring and their perceptions of college peers’ alcohol use in spring. We matched individuals into their rooms and residence halls to create a composite score of peer‐reported alcohol use for each of those levels. We examined multiple dimensions of peer influence and whether peer influence moderated genetic predisposition to predict college students’ alcohol use using multilevel models to account for clustering at the room and residence hall level. We found that polygenic scores (β= 0.12), perceptions of peer drinking (β= 0.37), and roommates’ self‐reported drinking (β= 0.10) predicted alcohol use (all ps<0.001), while average alcohol use across residence hall did not (β= −0.01, p =0.86). We found no evidence for interactions between peer influence and genome‐wide polygenic scores for alcohol use. Our findings underscore the importance of genetic predisposition on individual alcohol use and support the potentially causal nature of the association between peer influence and alcohol use. Genetic predisposition and peer influence, including perceived and self‐reported peer behaviors, are robust predictors of college student alcohol use. Using randomly assigned roommates, we found that perceived peer drinking was the strongest predictor of alcohol use. Genetic risk (measured via polygenic scores) and roommates’ self‐reported drinking also predicted alcohol use, but average residence hall drinking did not. Our findings underscore the importance of genetic predisposition on alcohol use and support the potentially causal nature of peer influence on alcohol use.