A genetic relatedness matrix (GRM) was estimated from a pruned set of semi-independent SNPs using the command line software GCTA (Yang et al., 2011) to facilitate estimation of the degree to which genetic factors contributed to marriage and divorce. In view of linkage disequilibrium (LD) differences across ancestral groups (Campbell & Tishkoff, 2008), separate GRMs were estimated for the EA (n SNPs = 423,096) and AA (n SNPs = 562,983) samples.
