title: Causal inferences: identical twins help and clarity about necessary assumptions is critical.
authors.affiliation: Department of Economics, Central Michigan University, Mount Pleasant, MI 48859, USA. Electronic address: amin1v@cmich.edu.
authors.forename: Vikesh
authors.initials: V
authors.lastname: Amin
authors.affiliation: William R. Kenan, Jr. Professor of Economics and Sociology, McNeil 160, 3718 Locust Walk, University of Pennsylvania, Philadelphia, PA 19104-6297, USA. Electronic address: jbehrman@econ.upenn.edu.
authors.forename: Jere R
authors.initials: JR
authors.lastname: Behrman
authors.affiliation: Fredrick J. Warren Professor of Demography, McNeil 272, 3718 Locust Walk, University of Pennsylvania, Philadelphia, PA 19104-6297, USA. Electronic address: hpkohler@pop.upenn.edu.
authors.forename: Hans-Peter
authors.initials: HP
authors.lastname: Kohler
authors.affiliation: School of Economics and Management, Southeast University, Jiangsu, China. Electronic address: xiongyanyan@seu.edu.cn.
authors.forename: Yanyan
authors.initials: Y
authors.lastname: Xiong
authors.affiliation: Department of Economics, Chinese University of Hong Kong, Shatin, NT, Hong Kong. Electronic address: jszhang@cuhk.edu.hk.
authors.forename: Junsen
authors.initials: J
authors.lastname: Zhang
mesh_terms: D015984:Causality; D015986:Confounding Factors, Epidemiologic; D004522:Educational Status; D059647:Gene-Environment Interaction; D005838:Genotype; D054624:Health Status Disparities; D006801:Humans; D064890:Social Determinants of Health; D018433:Twin Studies as Topic / Q000592:standards*; D014430:Twins, Monozygotic
keywords: Causal inference; Health; Schooling; Twins fixed-effects