66. Reznick, J. S. (1997). Intelligence, language, nature, and nurture in young twins. In R. J. Sternberg & E. L. Grigorenko (Eds.), Intelligence: Heredity and Environment. New York: Cambridge University Press.

The data presented in this chapter suggest one basis for asynchrony between expressive and receptive language during the second year: differential sensitivity to genetic and environmental influence. Apparently, environmental factors affect receptive language, but variance in expressive language is more difficult to account for because it is also affected by genetic mechanisms. This may also explain why individual differences in receptive language are strong predictors of subsequent MDI.