A forest plot of the heritability estimates for the adoption studies is presented in Fig. 2. Very few of the adoption studies individually produced significant estimates of the heritability of AUDs. However, when analyzed together, the estimate of heritability in males was 40.0% and statistically significant (95% CI 0.23–0.56, χ2 = 22.15, df = 1, p < 0.001). In females, the estimated heritability of AUDs was modest (0.241) but not statistically significant (95% CI 0.00–0.52, χ2 = 2.75, df = 1, p = 0.05). When the sexes were combined, no significant differences were seen between them, and the heritability was estimated at 0.36 with relatively wide CIs (0.22–0.50). The model fitting results for the adoption studies are presented in Table 5 and the parameter estimates are presented in Table 6.
