Does Marriage Moderate Genetic Effects on Delinquency and Violence?

Yi Li, University of North Carolina at Chapel Hill
Hexuan Liu, University of North Carolina at Chapel Hill
Guang Guo, University of North Carolina at Chapel Hill

Using data from the National Longitudinal Study of Adolescent Health (Add Health), we investigate whether marriage moderates genetic effects of 881 single nucleotide polymorphisms (SNPs) in 103 genes on delinquency and violence. The 103 genes are predominantly related to aggression and risky behavior. We extend a recently developed mixed linear model using the SNP data to estimate a heritability parameter—the proportion of variance in the phenotype that is explained by the SNPs' cumulative additive effects. The results show that the collective influence of the SNPs is considerably smaller for those who are married. Because issues such as selection, confounding and heterogeneity may bias the estimate of the gene-by-marriage interaction, we conduct a series of analyses to address these issues. The findings are supportive of the inference that the gene-by-marriage interaction results are not seriously affected by these issues.