1. Division of Psychological Medicine and Clinical Neurosciences, MRC Centre for Neuropsychiatric Genetics and Genomics (Riglin, A.K. Thapar, Langley, Collishaw, Tagg, A. Thapar), and School of Psychology (Livingston, Langley), Cardiff University, Cardiff, U.K.; MRC Integrative Epidemiology Unit, University of Bristol, Bristol, U.K. (Wootton, Davey Smith, Stergiakouli, Tilling)