mean level on the relevant environmental dimension, then no main effect of CHRM2 would be observed, as sampling is occurring essentially where the lines cross on Figure 4b. However, deviation from mean levels on the relevant environmental dimension (in either direction) would lead to the ability to detect significant main effects of CHRM2. This could explain the notable early replications of CHRM2’s effects across multiple independent samples, as many samples were clinical samples, and perhaps more likely than community samples to deviate from mean normative environmental conditions. (However, we note that an equally plausible explanation of mixed findings is normal sampling variability across studies trying to detect small genetic effects.)
