Abstract: Recent discoveries in the field of social-science genetics have produced credible genetic-based measures of economically-relevant traits. Yet, there is no consensus in this literature on whether inequalities driven by those measures are consistent, or inconsistent, with equality of opportunity. A similar disagreement is found in the literature of equality of opportunity regarding ‘inborn ability’ or ‘talents’. This disagreement is problematic, as being a proponent of equality of opportunity means dissimilar things to different individuals. This paper proposes two mathematical definitions of equality of opportunity in education, which consider both stances regarding inborn ability. Additionally, it shows how to proxy for inborn ability using the educational attainment polygenic risk score. This conceptual analysis can help to clarify and express existing positions within the equality of opportunity in education debate. An empirical application in the US Health and Retirement Study finds ignoring genetic differences overestimates equality of opportunity by up to 35%. Finally, there is persistent inequality of opportunity for younger cohorts (1948-1953) as compared to older cohorts (1926-1930), irrespective of the definition adopted. This result contrast with the increase in education for the younger cohorts.

The impact of the polygenic score construction method on the ranking of individuals in the polygenic score distribution

Co-authors: Stephanie von Hinke, Hans van Kippersluis, Fleur Meddens, Niels Rietveld

This paper compares the polygenic score-based ranking of individuals using different methods of construction.

Co-authors: Niels Rietveld; Hans van Kippersluis

Abstract: It is well-established that both the child’s genetic endowments as well as maternal smoking during pregnancy impact offspring birth weight. In this paper we move beyond the nature versus nurture debate by investigating the interaction between genetic endowments and this critical prenatal environmental exposure – maternal smoking – in determining birth weight. We draw on longitudinal data from the Avon Longitudinal Study of Parents and Children (ALSPAC) study and replicate our results using the UK Biobank. Genetic endowments of the children are proxied with a polygenic score which is constructed based on the results of a recent genome-wide association of birth weight. We instrument the maternal decision to smoke during pregnancy with a genetic variant (rs1051730) located in the nicotine receptor gene CHRNA3. This genetic variant is associated with the number of cigarettes consumed daily, and we present evidence that this is plausibly the only channel through which the maternal genetic variant affects the child’s birth weight. Additionally, we deal with the under-reporting of maternal smoking by using measures of cotinine, a biomarker of nicotine, collected from the mothers during their pregnancy. We confirm earlier findings that genetic endowments as well as maternal smoking during pregnancy significantly affects the child’s birth weight. However, we do not find evidence of meaningful interactions between genetic endowments and an adverse fetal environment, suggesting that one’s genetic predisposition cannot cushion the damaging effects of maternal smoking

Stop meta analyzing, start instrumenting: reducing measurement error in polygenic scores

Co-authors: Hans van Kippersluis, Stephanie von Hinke

This paper compares the explained variance of a polygenic score by comparing two different forms of aggregating GWAS summary statistics. Results suggest significant gains of instrumenting versus using the traditional meta-analysis of GWAS summary statistics.