plots the correlation each of monozygotic twins (MZ, red), dizygotic twins and siblings (DZ, blue) and unrelated individuals (UR, green) of (A) BAS residual score for all; (B) BAS residual score for girls; (C) BAS residual scores for boys; (D) BIS residual score for all; (E) BIS residual score for girls; (F) BIS residual scores for boys. The results of slope test of these regressions are shown in Supplementary Table S3. Regression lines were built using pairs of scores for MZ and DZ. “Subject 1” and “Subject 2” represent MZ or DZ twin pairs. For UR, pairs of children were randomly constructed by shuffling and splitting the sample into halves. This procedure was repeated 100 times, and mean regression lines were computed. 95% confidence intervals were calculated and are represented in the plot by shaded areas for MZ and DZ.