In Add Health, COGA, and the Philadelphia Neurodevelopmental Cohort (PNC), we next explored to what extent genome-wide polygenic scores for EXT were associated with childhood externalizing disorders and a variety of phenotypes that reflect difficulty with self-regulation or its consequences (Figure 3B and Supplementary Tables 29–31, see the tables for standard errors per hold-out sample). Polygenic scores for EXT explained significant variance (ΔR2) in criteria counts of ADHD (mean ΔR2 = 1.65%), conduct disorder (CD; mean ΔR2 = 3.1%), and oppositional defiant disorder (ODD; ΔR2 = 1.96%), as well as in the categories substance use initiation (mean ΔR2 = 1.3–6.5%), substance use disorders (mean ΔR2 = 0.8–1.7%), disinhibited behaviors (mean ΔR2 = 1.5–2.5%), criminal justice system involvement (mean ΔR2 = 1.0–3.0%), reproductive health (mean ΔR2 = 0.3–3.7%), and socioeconomic attainment (mean ΔR2 = 0.1–2.3%). Many of the phenotypes – such as opioid use disorder criteria count, conduct disorder and antisocial personality disorder criteria count, lifetime history of arrest or incarceration, and lifetime history of being fired from work – were not included in our Genomic SEM analyses. The associations between
