We examined whether attained socioeconomic status (SES) moderated genetic and environmental sources of individual differences in cognitive performance using pooled data from 9 adult twin studies. Prior work concerning SES moderation of cognitive performance has focused on rearing SES. The current adult sample of 12,196 individuals (aged 27-98…

Measures of general cognitive ability in one- and two-year-old adopted and nonadopted infants and their parents were subjected to path analysis to estimate the contribution of genetic and environmental factors to short-term stability of mental ability. (Author/RH)

Correlations on subscales of Wechsler intelligence quotient tests and the Revised Beta Examination were obtained for biologically related and unrelated individuals in 181 adoptive families in the Texas Adoption Project. Generally higher correlations for biologically related individuals support the importance of genetic influence in intellectual…

Investigated the etiology of several measures of cognitive delay in over 3,000 pairs of 2-year-old twins, focusing on group-differences heritability for general and specific cognitive delays. Concluded that because the genetic and environmental origins of verbal and performance delays in infancy differ, they are better considered separately rather…

Despite the importance of learning abilities and disabilities in education and child development, little is known about their genetic and environmental origins in the early school years. We report results for English (which includes reading, writing, and speaking), mathematics, and science as well as general cognitive ability in a large and…

Offers a brief overview of Murray and Herrnstein's "The Bell Curve: Intelligence and Class Structure in American Life." Discusses briefly the controversy surrounding the book and about research in the area of intelligence. Gives a background of solicited commentaries. (Author/JDM)

Examined the origins of high general cognitive ability (g) in twins who were participating in the MacArthur Longitudinal Twin Study. Formed high g groups from the 19th percentile and above at each age. Results suggested increasing genetic influence and increasing genetic stability from 14 to 36 months and substantial genetic influences with…

Studied continuity and change in general cognitive ability from infancy to adolescence in adoptees (107 children), biological siblings (87 pairs), and twins (224 monozygotic and 189 dyzygotic pairs). Findings generally support previous findings about genetic and environmental factors, with the exception that in the transition to adolescence,…

Hypothesizes that a child's realization of genetic potential for intellectual development depends on socioeconomic environment. Peabody Picture Vocabulary Test results were examined for a large sibling sample of African American and White adolescents from the National Longitudinal Study of Adolescent Health. When SES factors were considered…

A psychobiosocial model that is based on the inextricable link between the biological bases of intelligence and environmental events is proposed as an alternative to nature/nurture dichotomies. Societal implications and applications to teaching and learning are suggested. (MMU)

Presents a meta-analytic study based on the assumption that children's cognitive abilities can be both highly heritable and highly malleable. Results show strong support for the idea that early childhood education is a highly effective preventive intervention. Also finds that as preschool intervention intensity increases, so does the magnitude of…

Genetic effects on specific cognitive abilities as distinct from those on general cognitive ability were studied in 302 pairs of twins (some reared together, some apart) from the Swedish Adoption/Twin Study of Aging. Overall, results showed significant genetic influence on specific abilities independent of influence on general ability. (SLD)

The present study combined parallel data from the Northeast-Northwest Collaborative Adoption Projects (N2CAP) and the Western Reserve Reading Project (WRRP) to examine sibling similarity and quantitative genetic model estimates for measures of reading skills in 272 school-age sibling pairs from three family types (monozygotic twins, dizygotic…

The present study is a behavioral genetic analysis of specific cognitive abilities in early childhood. Parent-offspring data for adopted children and nonadopted children in the Colorado Adoption Project were used. Significant correlations were found between biological mothers' IQ and the IQ of offspring, but not for specific cognitive abilities.…

Examined the etiology of individual differences in literacy, phonological awareness, and language ability in monozygotic and dizygotic twins. Found that there was no genetic link between phonological awareness and literacy independent of general language ability. Individual differences in literacy ability were substantially influenced by genetics…