1. Psychology and Genetics Research Group, Guy’s King’s and St Thomas’s School of Medicine, Thomas Guy House, Guy’s Campus, London SE1 9RT, UK Department of Public Health Sciences, Guy’s King’s and St Thomas’ School of Medicine, Capital House, 42 Weston Street, London SE1 3QD, UK Sub-Department of Clinical Health Psychology, Department of Psychology, University College London, 1–19 Torrington Place, London WC1E 7HB, UK