Mental Health and Schooling: Causal Evidence Using Genetic Lotteries between Siblings

Jason Fletcher, Yale University
Steven F. Lehrer, Queen's University and National Bureau of Economic Research (NBER)

In this paper, we exploit “experiments in nature” by using genetic variation within siblings and within twins to identify the causal effect of several poor health conditions on academic outcomes via a family fixed effects / instrumental variables strategy. We use a subsample of the Add Health data to examine the impacts of depression, ADHD and obesity status during adolescence on completed years of schooling. We present compelling evidence of large impacts of poor mental health on years of schooling completed, dropping out of high school and idleness as a young adult. Our estimates suggest that accounting for family fixed effects is important, but these strategies cannot fully account for the endogeneity of poor mental health. Finally, our results demonstrate that the presence of comorbid conditions presents immense challenges for empirical studies that aim to estimate the impact of specific health conditions.