Psychopathy, Mental Deficiency, Aggressiveness and the XYY Syndrome

Abstract

IN a recent survey of mentally sub-normal male patients with “dangerous, violent or criminal propensities”, Jacobs and colleagues¹ found that seven of 197 inmates had an XYY sex chromosome constitution. This high frequency together with the findings of Casey et al.² in a similar population leads to the suggestion that one or more of the attributes of this type of institutional population may be associated with the presence of an extra Y chromosome. It was noted that these XYY males were strikingly tall compared with their fellow inmates, though otherwise physically unremarkable³. This was so marked in the original population that about 50 per cent of those 72in. tall or more were of XYY constitution. We have attempted to confirm and extend these investigations and report here our preliminary findings from a survey in a comparable population in the United States.