Genetic, Environmental, and Gender Effects on Individual Differences in Toddler Expressive Language In this article, the authors examined the genetic and environmental factors influencing expressive language development in a sample of 386 toddler twin pairs participating in the Wisconsin Twin Project. Expressive language was assessed using 2 measures from the MacArthur Communicative Development Inventories-Short Form: Total Vocabulary and Two-Word Combination Use (L. ... Research Article
Research Article  |   August 01, 2004
Genetic, Environmental, and Gender Effects on Individual Differences in Toddler Expressive Language
 
Author Affiliations & Notes
  • Carol A. Van Hulle
    University of Wisconsin-Madison
  • H. H. Goldsmith
    University of Wisconsin-Madison
  • Kathryn S. Lemery
    Arizona State University, Tempe
  • Corresponding author: e-mail: cvanhulle@bsd.health.uchicago.edu
  • Carol A. Van Hulle is now at the University of Chicago.
    Carol A. Van Hulle is now at the University of Chicago.×
Article Information
Development / Special Populations / Genetic & Congenital Disorders / Language / Research Articles
Research Article   |   August 01, 2004
Genetic, Environmental, and Gender Effects on Individual Differences in Toddler Expressive Language
Journal of Speech, Language, and Hearing Research, August 2004, Vol. 47, 904-912. doi:10.1044/1092-4388(2004/067)
History: Received September 23, 2002 , Revised February 18, 2003 , Accepted December 16, 2003
 
Journal of Speech, Language, and Hearing Research, August 2004, Vol. 47, 904-912. doi:10.1044/1092-4388(2004/067)
History: Received September 23, 2002; Revised February 18, 2003; Accepted December 16, 2003
Web of Science® Times Cited: 20

In this article, the authors examined the genetic and environmental factors influencing expressive language development in a sample of 386 toddler twin pairs participating in the Wisconsin Twin Project. Expressive language was assessed using 2 measures from the MacArthur Communicative Development Inventories-Short Form: Total Vocabulary and Two-Word Combination Use (L. Fenson et al., 2000). A sex-limitation structural equation model estimated the contribution of genetics, shared environment, and nonshared environment to individual variation. For vocabulary, heritability was higher for boys than for girls (20% vs. 8%). For word combination use, heritability was higher for girls (28% vs. 10%). However, the majority of individual variation in both boys and girls could be attributed to shared environment (54%–78%).

KEY WORDS: twins, language, toddlerhood, gender differences

Acknowledgments
This work was supported by National Institute of Mental Health (NIMH) Grants R01-MH59785 and R37-MH50560 (H. H. Goldsmith, Principal Investigator). This report was prepared while Carol A. Van Hulle was supported by NIMH Training Grant T32-MH18931.
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