Many studies have found associations between parent and child characteristics. Although genetic models partition phenotypic variance into genetic and environmental influences, parents’ genetic and environmental influences are confounded when children are raised by their biological parents. Kerr et al. (2013) separated mothers’ genetic and environmental influences by analyzing associations of depressive and antisocial characteristics of birth mothers (BM) and adoptive mothers (AM) with Internalizing and Externalizing scores obtained from CBCL/1½-5 forms completed separately by AM and by adoptive fathers (AF) when the children were 18, 27, and 54 months old.
The children were all born in the U.S. and adopted by families living in the U.S. After controlling for many variables, including obstetric risk factors, mothers’ prenatal depressive symptoms, and postnatal adoptive family contact with BM, Kerr et al found that BM lifetime depressive symptoms assessed via diagnostic interviews (surprisingly) predicted CBCL/1½-5 Externalizing scores, whereas BM antisocial behavior (surprisingly) predicted CBCL/1½-5 Internalizing scores. Moreover, AM depressive symptoms and antisocial behavior both predicted both CBCL/1½-5 Internalizing and Externalizing scores! Several AM predictive paths but not BM predictive paths were replicated in AF CBCL/1½-5 ratings. The replications in AF ratings indicated that the AM predictive paths were not artifacts of biases in AM CBCL/1½-5 ratings. However, the failure to replicate BM mothers’ predictive paths suggests that AM ratings but not AF ratings captured aspects of children’s problems not captured by AF ratings. The authors concluded that “depressive and antisocial dimensions of maternal psychopathology confer independent risks for . . . early childhood behavior outcomes” and that “This is consistent with recent factor-analytic, epidemiologic, and genetic studies that all point to two distinct, heritable liabilities underlying most comorbidity among psychiatric syndromes: an internalizing and externalizing factor” (p. 731).
Reference: Kerr, D.C.R., Leve, L.D., Harold, G.T., Natsuaki, M.N., Neiderhiser, J.M., Shaw, D.S., & Reiss, D. (2013). Influences of biological and adoptive mothers’ depression and antisocial behavior on adoptees’ early behavior trajectories. Journal of Abnormal Child Psychology, 41, 723-734.