The best fitting univariate model of divorce indicated that paths should be allowed to vary across sexes. According to this model, genetic factors accounted for a moderate proportion of the variance in divorce for males and females (estimates [95% CIs]: males 21.3% [7.6, 28.5] and females 31.0% [18.8, 37.1]). These estimates are consistent with two prior divorce heritability studies (estimates [95% CIs]: 15% [5, 19] and 32% [26, 38]) (19, 20) but are lower than the heritability estimate of 52.5% [41.9, 63.1] reported by McGue et al. (18). Nonshared environmental factors accounted for the majority of the variance in divorce for males and females (76.1% and 66.9%, respectively). Shared environmental factors were modest (2.7% and 2.1% of the variance in males and females) and did not differ from zero.
