Department of Economics
2101 E. Coliseum Blvd
Fort Wayne, IN 46805
NBER Working Papers and Publications
|August 2017||Testing for Peer Effects Using Genetic Data|
with John Cawley, Euna Han, Edward C. Norton: w23719
Estimating peer effects is notoriously difficult because of the reflection problem and the endogeneity of peer group formation. This paper tests for peer effects in obesity in a novel way that addresses these challenges. It addresses the reflection problem by using the alter’s genetic risk score for obesity, which is a significant predictor of obesity, is determined prior to birth, and cannot be affected by the behavior of others. It addresses the endogeneity of peer group formation by examining peers who are not self-selected: full siblings. Using data from the National Longitudinal Survey of Adolescent Health, we find evidence of positive peer effects in weight and obesity; having a sibling with a high genetic predisposition raises one’s risk of obesity, even controlling for one’s own ...