341: The Genetic Lottery and the Value of an Extra Year of School

Widding-Havneraas T et al., PNAS - This study uses genetic variation related to educational attainment as a quasi-experimental instrument (Mendelian randomization) together with Norwegian registry data to estimate the causal return to an additional year of schooling on labor-market earnings. Key terms: returns to education, Mendelian randomization, polygenic index, Norwegian registries, life-cycle earnings.

Study Highlights:
The authors triangulate OLS, sibling and twin fixed-effects, and Mendelian randomization (MR) using a 335-SNP polygenic index to estimate returns to schooling in Norwegian population and MoBa samples. OLS estimates an additional year of schooling raises prime-age earnings by about 5.9%, sibling FE by 5.3%, MZ twin FE by 3.3%, and MR by 8.0% (with a Norway-only MR estimate of 9.7%). Life-cycle analyses show negative early-career returns that turn positive around age 27 and grow thereafter. Internal rates of return across models exceed the market interest rate, indicating education is profitable over the life cycle.

Conclusion:
Using genetically informed quasi-experiments, one additional year of schooling causally increases annual earnings (MR ~8%), and education appears to pay off across the life cycle.

Music:
Enjoy the music based on this article at the end of the episode.

Article title:
Estimating returns to education using the genetic lottery

First author:
Widding-Havneraas T

Journal:
PNAS

DOI:
10.1073/pnas.2537049123

Reference:
Widding-Havneraas T, Demange PA, Zachrisson HD, Borgen N, Ystrom E, Elwert F. Estimating returns to education using the genetic lottery. PNAS. 2026;123(15):e2537049123. https://doi.org/10.1073/pnas.2537049123. Published April 8, 2026.

License:
This episode is based on an open-access article published under the Creative Commons Attribution 4.0 International License (CC BY 4.0) – https://creativecommons.org/licenses/by/4.0/

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QC:
This episode was checked against the original article PDF and publication metadata for the episode release published on 2026-04-13.

QC Scope:
- article metadata and core scientific claims from the narration
- excludes analogies, intro/outro, and music
- transcript coverage: Substantive audit focused on the episode’s discussion of methodology, key numerical results, lifecycle interpretation, and robustness checks as presented in the original article.
- transcript topics: Causality vs correlation in education and earnings; Mendelian randomization as a quasi-experiment; 335-SNP polygenic index as educational attainment instrument; Comparison across identification strategies: OLS, sibling, DZ/MZ twins, MR; Compliers and nonshared environments; Life-cycle returns and age-27 crossover

QC Summary:
- factual score: 10/10
- metadata score: 10/10
- supported core claims: 7
- claims flagged for review: 0
- metadata checks passed: 4
- metadata issues found: 0

Metadata Audited:
- article_doi
- article_title
- article_journal
- license
- episode_title
- episode_number
- season

Factual Items Audited:
- MR estimate: 8.0% increase in lifetime earnings per additional year of schooling
- OLS estimate: 5.9% increase per additional year of schooling
- Norway-only MR estimate: 9.7% per additional year
- Internal rate of return (IRR) to schooling: 10.1%
- Crossover age where returns become positive: about age 27
- Women experience higher fin...