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The distribution of height measurements on 11-year-old girls and boys of the National Child Development Study (NCDS) are analyzed together with the reported height of their mothers and fathers. Girls, boys, mothers and fathers all show the same type of deviation from normality. The distribution of the children’s height could be described by mixtures of three normal distributions. Being a member of the shortest of the three subpopulations is associated with but not adequately explained by congenital defects. The tall subpopulation comprises chil­dren at a relatively advanced stage of pubertal development, although it is thought that the distinctiveness of this subpopulation might diminish or disappear as the children grow up.