Cognitive ability and academic achievement in the Colorado Adoption Project: A multivariate genetic analysis of parent-offspring and sibling data

Abstract

To test the hypothesis that the etiology of covariation among measures of cognitive ability and academic achievement is due at least in part to shared genetic influences, data from 198 adoptive and 220 nonadoptive families participating in the Colorado Adoption Project were subjected to multivariate behavioral genetic analyses. Data on measures of cognitive ability (verbal comprehension and perceptual organization) and academic achievement (reading recognition and mathematics achievement) from related and unrelated sibling pairs tested at age 7, as well as from adoptive and nonadoptive parents, were analyzed. Phenotypic analyses confirmed previous findings of moderate correlations among measures of cognitive ability and achievement, averaging about .35. Although 54% of the covariation between reading and mathematics achievement was due to influences shared with verbal ability, a significant proportion of this covariation was independent of the cognitive ability measures. Heritabilities for the various measures were moderate, ranging from .21 to .37. Moreover, genetic influences accounted for 33-64% of their phenotypic covariation; for example, 33-60% of the observed correlations between verbal comprehension and the achievement measures, 64% of those between perceptual organization and the achievement measures, and 63% of that between reading recognition and mathematics achievement were due to shared genetic influences. Similar to the results of the phenotypic analysis, nearly half of the genetic covariance between reading and mathematics achievement was independent of cognitive ability. Their remaining covariance was due primarily to nonshared environmental influences.

School performance and weight status of children and young adolescents in a transitional society in Thailand

“…A report from the Colorado Adoption Project showed that cognitive ability and academic achievement at the age of 7 y were correlated and genetic in¯uences accounted for 33 ± 64% of these observed correlations. 24 These genetic and social environmental factors may be the main predictors of the association between overall school performance and BMI status in our study.…”

‘Generalist genes’ and mathematics in 7-year-old twins

“…In the only other twin study of the genetic overlap between mathematics and reading, a genetic correlation of 0.47 was found in a study of 220 MZ and 135 DZ twin pairs aged from 8 to 20 years (Knopik & DeFries, 1999). In an adoption study, the genetic correlation between reading and mathematical performance was 0.80 in a parent-offspring analysis (Wadsworth, DeFries, Fulker, & Plomin, 1995a) and 0.83 in a sibling analysis (Wadsworth, DeFries, Fulker, & Plomin, 1995b). One of these studies also explored the extent to which mathematics performance overlaps genetically with g. In a report based on 319 MZ and 251 DZ twin pairs aged from 8 to 20 years, the genetic correlation between latent factors of mathematics and g was 0.95 (Alarcón et al, 2000).…”

Heritability of Word Recognition in Middle-Aged Men Varies as a Function of Parental Education

“…Heritability estimates for different components of reading ability from twin (Brooks et al, 1990;Knopik and DeFries, 1999;Matheny and Dolan, 1974;Stevenson et al, 1987;Thompson et al, 1991) and adoption (Cardon et al, 1990;Wadsworth et al, 1995) studies in which participants were unselected for reading disability range from 0 to 0.69. Reading is a complex skill requiring multiple component processes, and the measurement of different component processes is one likely reason for the variability in results.…”

“…(We use the acronym WRAT to refer specifically to the reading subtest.) Heritability estimates for word recognition based on best fitting biometrical genetic models from previous studies with child and adolescent samples unselected for reading difficulties or samples selected as controls for participants with reading difficulties range from 0.19 to 0.49 (Brooks et al, 1990;Cardon et al, 1990;Knopik and DeFries, 1999;Stevenson et al, 1987;Wadsworth et al, 1999;Wadsworth et al, 1995).…”