Working Paper

Genetic markers as instrumental variables: an application to child fat mass and academic achievement


Debbie A. Lawlor, Carol Propper, Stephanie von Hinke, Frank Windmeijer, George Davey Smith

Published Date

2 March 2010


Working Paper (CWP03/10)

The use of genetic markers as instrumental variables (IV) is receiving increasing attention from economists. This paper examines the conditions that need to be met for genetic variants to be used as instruments. We combine the IV literature with that from genetic epidemiology, with an application to child adiposity (fat mass, determined by a dual-energy X-ray absorptiometry (DXA) scan) and academic performance. OLS results indicate that leaner children perform slightly better in school tests compared to their more adipose counterparts, but the IV findings show no evidence that fat mass affects academic outcomes.