The path estimates from the bivariate model displayed in Fig. 2 were used to derive the percentage of covariance and the phenotypic correlation due to each factor, which are shown in the bottom half of Table 5. The total expected phenotypic correlation of 0.14 results from the aggregate contributions of +0.10 (0.18 × 0.56) from common genetic factors, +0.07 ([0.42 × 0.08] + [0.35 × 0.11]) from the combination of common shared- and twin-environmental factors, and −0.03 (0.82 × −0.03) from common nonshared environmental factors. Therefore, much of the covariation between maltreatment and conduct problems is due to shared genetic factors (70%), a considerable portion to the combination of common shared-and twin-environmental factors (50%), and a negative contribution stems from nonshared environmental factors (−18%). The small negative value for nonshared environmental factors suggests that these factors alone would lead to a small negative correlation between maltreatment and conduct problems.
