Polygenic score analysis of educational achievement and intergenerational mobility

ALDO RUSTICHINI, William G. IACONO, James LEE, Matt MCGUE

Research output: Book/ReportCommissioned report

Abstract

A Genome-wide association study (GWAS) estimates size and significance of the effect of common genetic variants on a phenotype of interest. A Polygenic Score (PGS) is a score, computed for each individual, summarizing the expected value of a phenotype on the basis of the individual’s genotype. The PGS is computed as a weighted sum of the values of the individual’s genetic variants, using as weights the GWAS estimated coefficients from a training sample. Thus, P GS carries information on the genotype, and only on the genotype, of an individual. In our case phenotypes of interest are measures of educational achievement, such as having a college degree, or the education years, in a sample of approximately 2700 adult twins and their parents. We set up the analysis in a standard model of optimal parental investment and intergenerational mobility, extended to include a fully specified genetic analysis of skill transmission, and show that the model’s predictions on mobility differ substantially from those of the standard model. For instance, the coefficient of intergenerational income elasticity may be larger, and may differ across countries because the distribution of the genotype is different, completely independently of any difference in institution, technology or preferences. We then study how much of the educational achievement is explained by the PGS for education, thus estimating how much of the variance of education can be explained by genetic factors alone. We find a substantial effect of P GS on performance in school, years of education and college. Finally we study the channels between PGS and the educational achievement, distinguishing how much is due to cognitive skills and to personality traits. We show that the effect of PGS is substantially stronger on Intelligence than on other traits, like Constraint, which seem natural explanatory factors of educational success. For educational achievement, both cognitive and non cognitive skills are important, although the larger fraction of success is channeled by Intelligence.
Original languageEnglish (US)
StatePublished - 2018

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