The XYY genotype.

The epidemiological data pertaining to the XYY genotype suggest that there is a three- to fourfold overrepresentation of XYY individuals in mental and penal settings and a twentyfold overrepresentation of mental-penal (special security) settings. The reasons behind the risk for behavioral disability are not known at this time. Tallness and ondulocystic acne are reported frequently to be associated with the genotype. Since much of the available information about the XYY sex chromosome complement is biased, more data is required before definitive statements can be made about the personality characteristics or intelligence of the vast majority of XYY men not appearing in social settings oriented towards behavioral deviancy.