Social, Genetics and Developmental Psychiatry Research Centre, Institute of Psychiatry, Kings College London, De Crespigny Park, UK. s.purcell@iop.kcl.ac.uk|Social, Genetics and Developmental Psychiatry Research Centre, Institute of Psychiatry, Kings College London, De Crespigny Park, UK. s.purcell@iop.kcl.ac.uk|Social, Genetics and Developmental Psychiatry Research Centre, Institute of Psychiatry, Kings College London, De Crespigny Park, UK. s.purcell@iop.kcl.ac.uk