Second, we performed null simulations with a nonzero genetic correlation. 1% of SNPs had causal effects on L, and L had effects q1=q2=0.2 on each trait (so that ρg = 0.2). 4% of SNPs were causal for each trait exclusively (Figure 2b, Supplementary Table 2). MR and MR-Egger both produced excess false positives, while Bidirectional MR and LCV produced well-calibrated p-values. These simulations violate the MR-Egger assumption that the magnitude of pleiotropic effects on trait 2 are independent of the magnitude of effects on trait 1 (the ``InSIDE" assumption) [7], as SNPs with larger effects on L have larger effects on both trait 1 and trait 2 on average, consistent with known limitations [22].
