After controlling for participants’ measured (phenotypic) educational attainment in the polygenic analyses, EduYears-GPS continued to be associated with AUDSX and NDSX (but not CUDSX) (Supporting Information Table 2). After controlling for sibling and family differences in educational attainment in the sibling comparison analyses, the effects of sibling differences in EduYears-GPS on SUD criterion counts were attenuated for NDSX and CUDSX (P = 0.09 to 0.13) but remained significant for AUDSX (P = 0.01) (Supporting Information Table 3). Sibling and family differences in educational attainment were also significantly associated with SUD criterion counts. Individuals with higher educational attainment compared to their siblings, and individuals from sibling groups with higher educational attainment had lower AUDSX, NDSX, and CUDSX.
