Difficult to know if the effects of alcohol consumption on mate-selection are due to social factors or cohabitation leading to becoming more similar over time; found that genetic variants related to alcohol may, via effect on alcohol behaviour, influence mate selection

Alcohol consumption and mate choice in UK Biobank: comparing observational and Mendelian randomization estimates. Laurence J Howe, Dan J Lawson, Neil M Davies, Beate St. Pourcain, Sarah J Lewis, George Davey Smith, Gibran Hemani. bioRxiv, https://doi.org/10.1101/418269

Abstract: Alcohol use is correlated within spouse-pairs, but it is difficult to disentangle the effects of alcohol consumption on mate-selection from social factors or cohabitation leading to spouses becoming more similar over time. We hypothesised that genetic variants related to alcohol consumption may, via their effect on alcohol behaviour, influence mate selection. Therefore, in a sample of over 47,000 spouse-pairs in the UK Biobank we utilised a well-characterised alcohol related variant, rs1229984 in ADH1B, as a genetic proxy for alcohol use. We compared the phenotypic correlation between spouses for self-reported alcohol use with the association between an individual's self-reported alcohol use and their partner's rs1229984 genotype using Mendelian randomization. This was followed up by an exploration of the spousal genotypic concordance for the variant. We found strong evidence that both an individual's self-reported alcohol consumption and rs1229984 genotype are associated with their partner's self-reported alcohol use. The Mendelian randomization analysis, found that each unit increase in an individual's weekly alcohol consumption increased their partner's alcohol consumption by 0.29 units (95% C.I. 0.20, 0.38; P=2.15x10-9). Furthermore, the rs1229984 genotype correlated within spouse-pairs, suggesting that some spousal correlation existed prior to cohabitation. Although the SNP is strongly associated with ancestry, our results suggest that this concordance is unlikely to be explained by population stratification. Overall, our findings suggest that alcohol behaviour directly influences mate selection.