The present study is the first long-term longitudinal examination of the etiology of individual differences in language from early childhood through to adolescence. We applied a multivariate latent factor genetic model to longitudinal data from the Twins Early Development Study in order to (a) compare the magnitude of genetic and environmental…

Discusses the concept of temperament interactions in the context of statistical interaction. Categorizes temperament interactions that involve temperament as an independent variable, as a dependent variable, or as both. Describes use of hierarchical multiple regression for the analysis of temperament interactions. (Author/CI)

Focuses on possibility that correlations between measures of environment and child devleopment can be mediated genetically as well as environmentally. Proposing an elementary model to test this hypothesis, data from classical adoption studies and new data from the Colorado Adoption Project are used to illustrate the model and provide quantitative…

This study of 4,274 pairs of 4-year-old twins from the Twins Early Development Study explored the magnitude of genetic and environmental effects on low expressive vocabulary skill, both as a function of general cognitive ability and as a function of the severity of expressive vocabulary impairment. Assessments were conducted through parent report…