This study investigates the unique contributions and interactions of schooling, socioeconomic status (SES), and genetics on intelligence. Using a multi-trait polygenic score for cognition (cogPGS) and a regression discontinuity design, the study analyzed data from 6567 children (aged 9–11). Results showed large, independent effects of schooling, cogPGS, and SES on working memory, crystallized (cIQ), and fluid intelligence (fIQ). Two years of schooling had a larger effect on intelligence than the lifetime effects of SES or cogPGS inequalities. However, no interaction was found between schooling and cogPGS or SES, indicating that schooling did not lessen or widen the impact of these pre-existing factors.

Nicholas Judd, Bruno Sauce, Torkel Klingberg