Background: Parental depressive symptoms are associated with emotional and behavioural problems in offspring. However, genetically-informative studies are required to distinguish potential effects from familial confounds, and longitudinal studies are required to distinguish parent-tochild effects from child-to-parent effects.
Method: We conducted cross-sectional analyses on a sample of Swedish twins and their adolescent offspring (N = 876 twin families), and longitudinal analyses on a US sample of children adopted at birth, their adoptive parents, and their birth mothers (n = 361 adoptive families). Depressive symptoms were measured in parents, and externalising and internalising problems measured in offspring. Structural Equation models were fitted to the data.
Results: Results of model fitting suggest that associations between parental depressive symptoms and offspring internalising and externalising problems remain after accounting for genes shared between parent and child. Evidence for genetic transmission appeared stronger for the relationship between parental depressive symptoms and youth externalising problems. Child-to-parent effects were evident in the longitudinal adoption study.
Conclusions: We interpret the results as demonstrating that associations between parental depressive symptoms and offspring emotional and behavioural problems are not solely attributable to shared genes, that bidirectional effects may be present in intergenerational associations, and that adult depressive symptoms may share greater genetic overlap with child externalising than with child internalising.