Fertility Outcomes, Heritability and Genomic Associations of In-Group Preference and In-Group Marriage.

Fieder, M., , Huber, S., 2021. Fertility Outcomes, Heritability and Genomic Associations of In-Group Preference and In-Group Marriage. Twin Research and Human Genetics 24, 264-272.


Using data from the Midlife Development in the USA (MIDUS) sample (3070 men and 3182 women) and the Wisconsin Longitudinal Study(WLS; 2240 men and 2346 women), we aimed to investigate whether religious, ethnic and racial in-group preferences as well as religioushomogamy are associated with reproductive outcome in terms of number of children. Using data from the MIDUS twin sample, we furtherestimated the inherited genetic component of in-group attitudes. Additionally, we analyzed the association of∼50 polygenic scores (PGSs)recently published for the WLS study and in-group attitudes as an indicator of potential pleiotropic effects. We found in both samples that,with one exception, religious though not other in-group attitudes are associated with a higher reproductive outcome. Also, religioushomogamy is associated with higher average number of children. The inherited component of all in-group attitudes ranges from∼21%to 45% (MIDUS twin sample). PGSs associated with religious behavior are significantly positively associated with religious in-group attitudesas well as family attitudes. Further associations are found with PGS on life satisfaction (work) and, negatively, with PGS for any sort of addic-tion (smoking, alcohol and cannabis use), indicating pleiotropy. We conclude that the positive association between religious in-group attitudesas well as religious homogamy and reproductive outcome may indicate selective forces on religious in-group behavior. As all investigated in-group attitudes, however, have a substantial inherited component, we further speculate that potential previous reproductive benefits of racialand ethnic in-group preferences, if they ever existed, might have been substituted by religious in-group preferences.Keywords:In-group favouritism and homogamy; reproduction; heritability; evolution; polygenic scores (Received 7 October 2021; accepted 8 November 2021)

Read full article

Research Areas: