Genetics of Educational Attainment and Childhood Problem Behavior: Direct Genetic Effects, Cognitive Pathways, and Sex Differences.

We examined the genetic underpinnings of problem behavior in children and adolescents (4-17 years old) by leveraging a within-family trio design using data of European ancestry from the Lifelines cohort (N=3,160-4,611). We estimated direct genetic effects of educational attainment (EA) polygenic indices (PGIs), as a whole and decomposed into cognitive (Cog) and non-cognitive (NonCog) components via GWAS-by-subtraction, on a comprehensive set of internalizing and externalizing behaviors assessed via self- and parental report Achenbach System of Empirically Based Assessment (ASEBA) measures. We found that higher EA PGIs, particularly their Cog component, were robustly associated with lower levels of Attention Problems and Somatic Complaints, in parental and self-report samples respectively. These associations persisted after adjusting for parental PGIs, supporting a causal interpretation under counterfactual reasoning. In contrast, the NonCog EA PGI showed weaker and less consistent associations with problem behavior, though we cannot rule out that this reflects limited power to detect smaller effects. We observed pronounced sex differences, with associations largely driven by girls, for whom the Cog component was the primary predictor. In the self-report sample in particular, associations with Somatic Complaints were significantly stronger in girls, with no significant findings observed for boys. We also found that associations with Somatic Complaints were significantly larger in the self-report than the parental report sample, while for other scales, differences across informants were statistically negligible. Our findings contribute to a more holistic understanding of how EA-related genetics manifest in socioemotional processes beyond academic achievement.