We performed sample-size weighted meta-analysis with METAL (versions 2011-03-25 and 2020-05-05)66, while ensuring absence of sample overlap (Supplementary Information section 2.5.1). We excluded any summary statistics with negligible SNP-based heritability (h2 < 0.05) or GWAS signal (χ¯2 < 1.05), estimated with LD Score regression (version 1.0.0)12,55. At this stage, we had collected or generated well-powered summary statistics for 11 phenotype-specific GWAS (or meta-analysis) that satisfied our inclusion criteria (Supplementary Table 3): (1) attention-deficit/hyperactivity disorder (ADHD, N = 53,293), (2) reverse-coded age at first sexual intercourse (FSEX, N = 357,187), (3) problematic alcohol use (ALCP, N = 164,684), (4) automobile speeding propensity (DRIV, N = 367,151), (5) alcoholic drinks per week (DRIN, N = 375,768), (6) reverse-coded educational attainment (EDUC, N = 725,186), (7) lifetime cannabis use (CANN, N = 186,875), (9) lifetime smoking initiation (SMOK, N = 1,251,809), (9) general risk tolerance (RISK, N = 426,379), (10) irritability (IRRT, N = 388,248), and (11) number of sexual partners (NSEX, N = 336,121) (Supplementary Table 4). The GWAS effect-sizes of age at first sexual intercourse and educational attainment were reversed to anticipate positive correlations with externalizing liability.
