We extended Genomic SEM to estimate genetic correlations between EXT and 91 preregistered phenotypes with GWAS summary statistics that were not among the seven discovery phenotypes (Extended Data Fig. 1 and Supplementary Table 8). The genetic correlations indicate convergent and discriminant validity of the common EXT factor (Figure 1C): As anticipated, EXT showed strong positive genetic correlations with drug exposure (rg = 0.91, SE = 0.09), antisocial behavior (rg = 0.65, SE = 0.17), and impulsivity measures, including motor impulsivity (rg = 0.70, SE = 0.17) and failures to plan (rg = 0.68, SE = 0.13). We estimated similar genetic correlations with personality domains (based on 23andMe20) as to those reported in twin studies, i.e., positive correlation with extraversion (rg = 0.32, SE = 0.03), and negative with conscientiousness (rg = −0.23, SE = 0.04) and agreeableness (rg = −0.09, SE = 0.04)11,21. However, prior work has found neuroticism but not openness to be correlated with externalizing21, while we found a positive correlation with openness (rg = 0.22, SE = 0.04) but not with neuroticism (rg = 0.02, SE =
