1 Jeremy Coid, Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Wolfson Institute of Preventive Medicine, Centre for Psychiatry, Forensic Psychiatry Research Unit, William Harvey House, 61 Bartholomew Close, London EC1A 7BE, UK. Email: j.w.coid@qmul.ac.uk; Simone Ullrich, Constantinos Kallis, Queen Mary University of London, Barts and The London School of Medicine and Dentistry, Wolfson Institute of Preventive Medicine, Centre for Psychiatry, Forensic Psychiatry Research Unit, London, UK.