During childhood and adolescence, increases in heritability and decreases in shared environmental influences have typically been found for cognitive abilities. A sample of more than 2,500 pairs of twins from the Twins Early Development Study was used to investigate whether a similar pattern would be found for science performance from 9 to 12…

Five experiments investigated children's intuitions about genetic transmission of features. Results suggest young children have principled, specifically biological notions of inheritance. (PCB)

Findings indicated that zygosity was not related to behavioral scores during the neonatal period, and that environment substantially influenced neonatal temperament. Specific perinatal indicators of risk were found to account for some of the intrapair differences in behavioral variables. (RH)

Explored the roles of genes and environment in masculinity and femininity during pre- and early adolescence in 70 twins of 8-14 years. Results revealed significant genetic influences in all measures. Environmental influences were specific to each individual and not shared by members of the same twin pair. (RJC)

Investigated genetic change and continuity within the domains of temperament, emotion, and cognition and language for 200 pairs of twins assessed at 14 and 20 months of age. Correlations of measures at the two ages indicated that individual differences in the second year of life showed greater change than continuity on most measures. (MDM)

Estimates the extent to which heredity influences perceptions of childhood family environment in a sample of 58 monozygotic and 46 dizygotic pairs of adult twins who were reared apart. The data confirm the importance of genetic factors in some, but not all, measures of family environment. Environmental influences were more important than genetic…

Considered variations in pubertal timing, specifically age at menarche, and association with various antecedents, including heredity; weight and weight for height; stressful life events; family relations; absence or presence of adult male in household; and psychological adjustment, in 75 premenarcheal adolescent girls. Found complex interactions…

Examined low interrater agreement by decomposing common and unique variance among parent, adolescent, and observer reports of parental warmth and negativity into genetic and environmental factors. Model-fitting analyses findings generally supported predictions for warmth and negativity at Family and Individual levels. At the Social level, genetic…

Four experiments explored adults' and grade school children's beliefs about inheritability of racial identity. Found that older children and adults believed that mixed-race children possessed black racial features. Also found that children from an integrated school, regardless of race, expected mixed-race children to have intermediate racial…

Examined the contribution of biological and environmental variables to 11-year-olds' phonological development. Found that temporal lobe (planar) asymmetry, hand preference, family history of reading disability, and SES explained over half the variance in phonological and verbal performance, demonstrating a linear association between cerebral…

Factor analysis of 25 rating scales from Bayley's infant behavior record were performed for a sample of about 300-400 infant twins tested one or more times between 3 and 24 months of age. The analyses provided five major and two minor factors that were considerably consistent at all ages. (Author/DB)