between best estimate IQ and SOC was still significant but with IQ accounting for less than 1% of the total variance of SOC. Since the inclusion of best estimate IQ would reduce the sample size by approximately one quarter due to missing values in IQ, it was not included as a covariate for SOC. Tables 2 and 3 in Supplement 1 list the effects of the selected covariates for SOC and BEH, respectively. The heritability estimate was .35 (p = 5 × 10−9) for SOC and .52 (p = 5 × 10−17) for BEH.
