Eirik Haugland Kvalvik

• Kvalvik, Eirik Haugland; Wang, Yunpeng; Walhovd, Kristine B; Lyngstad, Torkild Hovde & Røgeberg, Ole (2026). Beyond years of schooling: Genetic associations across educational milestones in two Norwegian cohorts. PLoS Genetics. ISSN 1553-7390. 22(9). doi: 10.1371/journal.pgen.1012310. Full text in Research Archive Show summary

  Although educational attainment is heritable, years-of-education (EduYears) measures are not designed to show how genetic associations vary across discrete educational milestones. In the Norwegian Mother, Father and Child Cohort Study (MoBa; N = 120,527) and the Norwegian Twin Registry (N = 8,910), we combined genome-wide association studies (GWAS), polygenic indices (PGIs), and twin models to characterize genetic associations with high-school completion and bachelor’s, master’s, and doctoral attainment. In transition-specific analyses conditional on prior attainment, observed-scale common-variant heritability (h 2 SNP ) and PGI discrimination followed an inverse-U pattern, peaking for progression from high-school completion to attainment of at least a bachelor’s degree (HS → BSc + ; h 2 SNP  ≈ 0.14; R 2 Tjur  ≈ 0.05) and declining at postgraduate transitions. Genetic correlations (r g ) with large-scale GWAS of EduYears (EA4) and intelligence were high at earlier transitions but lower at later ones (for EA4, r g  ≈ 0.92 at HS → BSc+ and ≈ 0.38 at MSc → PhD). In cumulative analyses of attained status in the full cohort, the point-estimate gap between twin- and SNP-based heritability narrowed from ≈ 0.38 at high-school completion to ≈ 0.11 at PhD, while genetic overlap was lower for distant than adjacent milestones (r g  ≈ 0.71 for high-school completion versus PhD and ≈ 0.92 for adjacent milestones). Sensitivity analyses using an alternative intelligence GWAS and additional PGIs showed similar transition-specific trajectories. At the doctoral transition, estimates were obtained among individuals who had attained at least a master’s degree, so attenuation there must be interpreted in light of selection and range restriction. Because EduYears converts distinct credentials and progression steps into a single numerical scale, estimates expressed per additional year should not be interpreted as though one year has the same meaning across the educational sequence. Milestone-preserving analyses make that hidden structure visible and sharpen the interpretation of education GWAS and PGIs.

• Kvalvik, Eirik Haugland; Røgeberg, Ole; Wang, Yunpeng; Lyngstad, Torkild Hovde & Walhovd, Kristine B (2025). Beyond years of schooling: Shifting genetic influences across educational milestones in two Norwegian cohorts | bioRxiv. bioRxiv. ISSN 2692-8205. doi: 10.1101/2025.10.08.680992. Full text in Research Archive Show summary

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• Kvalvik, Eirik Haugland; Røgeberg, Ole; Wang, Yunpeng & Lyngstad, Torkild Hovde (2024). Triangulating Evidence of Declining Heritability Across Educational Levels in Norway: Insights from Twin Models and Polygenic Scores. Behavior Genetics. ISSN 0001-8244. 54(6), p. 483–483. doi: 10.1007/s10519-024-10197-8. Full text in Research Archive Show summary

  Although the genetic basis for educational attainment has been extensively studied, the progression from high school to doctoral levels remains less understood. Therefore this study employs a sequential hurdle model for analyses of twin models (N = 8910, cohorts 1965–2001) and polygenic scores (PGS, N = 114,699, cohorts 1965–1989) to explore the additive genetic effects (A) for these educational transitions across Norwegian cohorts. Findings indicate that genetic influence decreases with higher educational hurdles: for high school graduates, A = 0.6 [0.39, 0.76]; for bachelor’s degree holders, A = 0.49 [0.36, 0.64]; for master’s degree holders, A = 0.42 [0.23, 0.61]; and for doctorate holders, A = 0.3 [0.02, 0.6]. Similarly, McFadden’s pseudo R2 from PGS revealed decreasing genetic influence from high school (0.047 [0.044, 0.051]) to PhD (0.01 [0.007, 0.013]). The study also finds a selection effect, where individuals with higher PGS are more likely to surpass educational milestones, evidenced by the adjusted mean standardized PGS increasing almost linearly with educational level, from high school (- 0.29 [- 0.3, - 0.28]) to PhD (0.72 [0.67, 0.76]). This suggests that for each educational hurdle passed, the less genetic influences matter for passing the next hurdle, but that there is a selection process where individuals with higher PGS tend to more easily pass higher educational hurdles.

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