Behaviour Disorders and Pattern of Crime among XYY Males Identified at a Maximum Security Hospital

Abstract

The behaviour of nine male patients with an XYY sex chromosome complement has been analysed and assessed. It was found that (a) they suffered from a severe disorder of personality, in most instances associated with intellectual impairment, which it is suggested is due to the extra Y chromosome; (b) in their criminal behaviour they displayed less violence against persons than did control patients; (c) they began their criminal activities at a very young age, on average five years earlier than other patients at the hospital ; (d) they had no significant family history of crime or mental illness; and (e) their criminal behaviour had proved in the past to be resistant to conventional forms of corrective training and treatment. The significance of these findings is briefly discussed. © 1967, British Medical Journal Publishing Group. All rights reserved.