Twin children were videotaped hitting an inflated clown figure. Three behaviors (number of hits, intensity of hits, and number of quadrants hit) showed adequate response characteristics, rater reliability, and test-retest reliability. Twin analyses of the three behavioral ratings yielded no evidence of hereditary influence. (Author)

The study of genotype-environment interaction (G x E) has been dominated by two competing hypotheses, one that heritability is greater in high-risk environments (diathesis-stress) and the other that heritability is greater in permissive environments. The current study examined relationships between verbal and nonverbal abilities and 10 measured…

Explored origins of individual differences in infant shyness by studying its relationship to parental shyness, sociability, and introversion-extraversion. Full adoption design examined role of both genetic and family environmental influences as possible etiological factors in development of infant shyness. Results indicate genetic influences and…

Studied genetic and environmental origins of individual differences in adults' (N=386) ratings of their current family environment using Moos Family Environment Scales (FES). Found 25 percent of adults' FES scores due to genetic differences. Found environment in which they were reared had little effect on adults' ratings of their family…

Provides an overview of a longitudinal, prospective, multivariate adoption study of behavioral development and discusses the results of analyses of cognitive measures and environmental assessments as examples of the types of information that can emerge from a design of this sort. (Author/RH)

The current study examined whether socioeconomic status (SES) and chaos in the home mediate the shared environmental variance associated with cognitive functioning simultaneously estimating genetic influences in a twin design. Verbal and nonverbal cognitive development were assessed at 3 and 4 years for identical and same-sex fraternal twin pairs…

Extensive data on twins, nontwin siblings, siblings separated by adoption, and parent-child similarity indicate that the heritability of intelligence is closer to .50 than to .70. Differences could be due to environmental or genetic changes in the population, or to methodology. (Author/CP)

Used the Sibling Inventory of Differential Experience with 396 adolescent and young adult children to determine the extent to which genetic differences between siblings or sibling differences in family constellation variables were responsible for differential experiences. (HOD)