The effect of weight on labor market outcomes : an application of genetic instrumental variables / Petri Böckerman (Turku School of Economics, IZA and Labour Institute for Economic Research), John Cawley (Cornell University and IZA), Jutta Viinikainen (Jyväskylä University School of Business and Economics), Terho Lehtimäki (University of Tampere), Suvi Rovio (University of Turku), Ilkka Seppälä (University of Tampere), Jaakko Pehkonen (Jyväskylä University School of Business and Economics), Olli Raitakari (University of Turku and Turku University Hospital) ; IZA