Unpacking the relationship between parenting behaviours and child aggression: Triangulating different causal inference models across two cohorts

High or persistent levels of aggression are associated with psychopathology and difficulties with health and education as the child develops. Parenting behaviours have been frequently associated with childhood aggression, however much of this literature does not control for the shared genetics between parent and child or investigate the direction of effects. Here, we triangulated across two family-based designs, the Norwegian Mother Father and Child Cohort Study (MoBa) and the Early Growth and Development Study (EGDS) from the United States, both of which have comparable measures and allow for direction-of-causation analysis and control for shared genetics. Analyses were pre-registered.We found converging evidence across both studies for both genetic and environmental transmission in the relationship between parenting behaviours and child aggressive behaviour, with the association between positive parenting and lower child aggression being driven primarily by shared genetics. In MoBa, 47% of the association between inconsistent parenting and child aggression was explained by shared genetics. We found significant child-to-parent effects in both the MoBa and the EGDS samples. This work shows the strength of triangulation, allowing us to describe a pattern of intergenerational association that is not dependent on a specific sample or study design.