A recent study reported genetic correlations between various complex traits and number of children in males and females[52]. We identified only one trait (balding in males) with a fully or partially causal effect on number of children (in males; Table 1). For college education, which has a strong negative genetic correlation with number of children (ρ^g = −0.31(0.07) and −0.26(0.06) in males and females respectively), we obtained low gcp estimates with low standard errors (gcp^ = 0.00(0.09) and gcp^ = 0.04(0.21) respectively, Supplementary Table 12). Thus, a genetic correlation with number of children does not imply direct selection. This result does not contradict the conclusion of reference [52] that complex traits are affected by natural selection, as pleiotropic selection can also affect a trait [53].
