Common aetiology for diverse language skills in 41/2-year-old twins 1
Multivariate genetic analysis was used to examine the genetic and environmental aetiology of the interrelationships of diverse linguistic skills. This study used data from a large sample of 4[fraction one-half]-year-old twins who were tested on measures assessing articulation, phonology, grammar, vocabulary, and verbal memory. Phenotypic analysis suggested two latent factors: articulation (2 measures) and general language (the remaining 7), and a genetic model incorporating these factors provided a good fit to the data. Almost all genetic and shared environmental influences on the 9 measures acted through the two latent factors. There was also substantial aetiological overlap between the two latent factors, with a genetic correlation of 0·64 and shared environment correlation of 1·00. We conclude that to a large extent, the same genetic and environmental factors underlie the development of individual differences in a wide range of linguistic skills.(Received October 29 2004)
(Revised September 23 2005)
c1 Department of Psychology, University of York, Heslington, York YO10 5DD. e-mail: email@example.com
1 We gratefully acknowledge the ongoing contribution of the parents and children in the Twin Early Development Study (TEDS). TEDS is supported by a programme grant (G9424799) from the UK Medical Research Council.