Origins of Individual Differences in Imitation: Links With Language, Pretend Play, and Socially Insightful Behavior in Two-Year-Old Twins



This article is corrected by:

  1. Errata: Errata Volume 78, Issue 3, 1033–1034, Article first published online: 16 May 2007

  • Twins' Early Development Study (TEDS) is supported by program Grant G0500079 from the U.K. Medical Research Council. The authors are indebted to the parents of the twins in the TEDS for making the study possible.

concerning this article should be addressed to Fiona McEwen, Social Genetic and Developmental Psychiatry (SGDP) Centre, Box P080, Institute of Psychiatry, De Crespigny Park, London, SE5 8AF, U.K. Electronic mail may be sent to


Imitation, vocabulary, pretend play, and socially insightful behavior were investigated in 5,206 same- and opposite-sex 2-year-old twin pairs in the United Kingdom. Individual differences in imitative ability were due to modest heritability (30%), while environmental factors shared between twins (42%) and unique to each twin (28%) also made significant contributions to the variance. Imitation correlated significantly, although modestly, with vocabulary, pretend play, and socially insightful behavior, and the strongest relationship was with vocabulary. A model that represented the covariance between the variables as being due to correlated latent genetic and environmental factors fitted the data well, with shared environmental factors influencing most of the covariance. Parents who encourage imitation may also tend to foster the development of language, pretence, and socially insightful behavior.