Activity Level and Hyperactivity in Twins

Abstract

WILLERMAN, LEE. Activity Level and Hyperactivity in Twins. CHILD DEVELOPMENT, 1973, 44, 288-293. The mothers of 93 sets of same-sexed twins completed questionnaires on activity level and zygosity in their twins. Intraclass correlations for activity level in monozygotic twins (MZs) were substantially higher than for dizygotic twins (DZs). Among twin sets where at least 1 member scored in the hyperactive range on the questionnaire (upper 20%), MZ twins showed a high correlation for activity level while DZ twins showed no correlation. The results were interpreted as suggesting a substantial heritable component to activity level.