Basic estimates of heritability are presented in Table 1. As seen there, both CP and parent–child conflict evidenced small-to-moderate genetic influences. Shared environmental influences, by contrast, were moderate to large in magnitude, in keeping with prior work (Burt, 2009b). We also present MZ and DZ intraclass correlations separately by level of conflict experienced. Although these results do not constitute a formal test of etiological moderation, the pattern of MZ–DZ differences observed across the cells is consistent with either decreasing genetic influences and/or increasing shared environmental influences on CP with increasing levels of parent–child conflict.
