Testing for Peer Effects Using Genetic Data

44 Pages Posted: 21 Aug 2017 Last revised: 24 Apr 2022

See all articles by John Cawley

John Cawley

Cornell University - College of Human Ecology, Department of Policy Analysis & Management (PAM); Cornell University - College of Arts & Sciences, Department of Economics; Erasmus University Rotterdam (EUR) - Erasmus School of Economics (ESE); University of Galway - J.E. Cairnes School of Business & Economics; NBER; IZA

Euna Han

College of Pharmacy, Yonsei University

Jiyoon Kim

Korea University Business School (KUBS)

Edward C. Norton

University of Michigan at Ann Arbor

Date Written: August 2017

Abstract

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 genetic predisposition to obesity. Implications of the findings include that peer effects may be an explanation for continued worldwide increases in weight, and that, because of social multipliers, the cost-effectiveness of obesity treatment and prevention programs may have been underestimated.

Suggested Citation

Cawley, John and Han, Euna and Kim, Jiyoon and Norton, Edward C., Testing for Peer Effects Using Genetic Data (August 2017). NBER Working Paper No. w23719, Available at SSRN: https://ssrn.com/abstract=3023117

John Cawley (Contact Author)

Cornell University - College of Human Ecology, Department of Policy Analysis & Management (PAM) ( email )

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Cornell University - College of Arts & Sciences, Department of Economics ( email )

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IZA ( email )

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Euna Han

College of Pharmacy, Yonsei University ( email )

Seoul
Korea, Republic of (South Korea)

HOME PAGE: http://works.bepress.com/euna_han

Jiyoon Kim

Korea University Business School (KUBS) ( email )

Anam-Dong, Seongbuk-Gu
Seoul 136-701, 136701
Korea

Edward C. Norton

University of Michigan at Ann Arbor ( email )

500 S. State Street
Ann Arbor, MI 48109
United States

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