The Interaction Between Genes and Environment in Determining Health and Education Inequalities: the Impact of in Utero Exposure to Nicotine on Weight and Cognition Later in Life

Abstract: There is a vast medical literature exploring the consequences of in-utero exposure to nicotine. This paper makes use of an innovative approach in an attempt to solve two of the most common issues in this literature: the under reporting of smoking and its endogenous character. First, we use a measure of cotinine, a biomarker of nicotine, in order to account for underreporting of smoking during pregnancy. We find that the self-reported level of smoking is 23% while 33% of the mothers had enough cotinine in their urine to be considered active smokers. Second, to deal with the endogeneity of smoking, we instrument the decision to smoke during pregnancy with a single SNP located in the nicotine receptor gene CHRNA3. Finally, we explore heterogeneous effects across children with different genetic susceptibilities with respect to educational attainment and weight.