Path analysis of general and specific cognitive abilities in the Colorado adoption project: Early childhood

Abstract

A path model of genetic and environmental transmission was fitted to general and specific cognitive abilities (verbal, spatial, visual memory, and perceptual speed) data from biological, adoptive, and control parents and their children at ages 3 and 4. Using a maximum-likelihood estimation procedure. the significance of genetic influence, passive genotype-environment correlation, parental influence on the child's environment, assortative mating, and selective placement was assessed. As predicted, the parameter estimate for genetic influence (a function of the heritabilities of the character during early childhood and adulthood and their genetic correlation) is significant for general cognitive ability at both 3 and 4. Moreover, estimates of the genetic parameter are significant for spatial ability at both 3 and 4 years of age, for verbal ability at 3, and for perceptual speed at 4. Thus, there is at least some continuity between early childhood and adulthood as well as some genetic differentiation for specif cognitive abilities.