Fig. 1.

Path diagrams showing the relationship between parental depression and offspring internalizing/externalizing problems. Path estimates are taken from the full (unconstrained) models in which all parameters are freely estimated. A1, Additive genetic effects on parental depression; C1, shared-environmental effects on parental depression; E1, non-shared environmental effects on parental depression; A1′, genetic effects common to parental depression and offspring phenotype; A2, familial effects specific to offspring phenotype; E2, non-shared environmental effects on offspring phenotype. Note that the pathway between A1 and A1′ is fixed to 0.50 because parents and children share 50% of their genome.