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Abstract
Recent behavioral genetic research has shown that genetic propensities are associated with individual differences in experiences, and thus, what may appear to be environmental effects can reflect genetic influence. This study examines passive genotype-environment correlations (GECs) for language-related abilities by comparing environment-child language associations in adoptive and nonadoptive families. The results provide evidence for the genetic mediation of the association between home environmental variables, such as the provision of toys and games, maternal involvement, and degree of intellectual/cultural orientation with children's language-related abilities. Developmental changes in passive GECs are considered, and the implications for typical and atypical learners are discussed.
Behavioral genetic research has contributed to our understanding of the basis for individual differences in personality and cognition (Plomin, DeFries, McClearn, & McGuffin, 2001). As our understanding of gene-environment relationships has increased, this research has moved beyond simply estimating genetic and environmental main effects for phenotypes, commonly referred to as heritability and environmentality. Studies have turned their focus to more complex issues in etiology, such as how genes and environments interact to produce phenotypes or how environments can be modified by genes, thus complicating the apparent causal paths by which variance in a phenotype is generated (Gilger, 2000; Plomin, 1994; Plomin et al., 2001; Sherman et al., 1997).
One of the complexities in studying the etiology for traits such as language is the existence of gene-environment relationships called genotype-environment correlations (GECs). GECs refer to the selective exposure of different genotypes to different environments (Plomin, DeFries, & Loehlin, 1977) or to the genetic control of exposure to the environment (Kendler & Eaves, 1986). Three types of GECs have been described (Plomin et al., 1977; Scarr & McCartney, 1983): evocative (or reactive), active, and passive. The relative importance of these three GECs is expected to change with age, such that passive forms are more significant early in life and evocative and active forms become increasingly powerful as the individual grows older (Scarr & McCartney, 1983).
In the context of language ability, evocative GEC may occur when linguistically talented children are identified by teachers and provided with special opportunities such as participation on debate teams, journalism, or forensic clubs and activities; that is, the children "evoke" reactions from other individuals on the basis of their...