THE GROWTH AND DEVELOPMENT OF FOUR XYY INFANTS

Abstract

Four XYY infants ascertained from 1,066 unselected newborn infants have been followed for 2½ to 3½ years. None of them show any distinctive physical characteristics, though three of the four lack a C triradius in the palmar dermatoglyphics. All four are of normal stature. Three appear of normal intellect and personality. One is of borderline intelligence and by 2 years was exhibiting aggressive, defiant, and destructive behavior. There are great problems of what, if anything, to divulge to the parents when an XYY chromomosome complement has been discovered.