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)

Conducted a trivariate genetic analysis of the Home Observation for Measurement of the Environment (HOME), Mental Development Index (MDI), and Task Orientation (TO). Found that for 101 nonadoptive and 92 adoptive sibling pairs at 12 and 24 months of age, TO explained the remaining genetic variance on the HOME not explained by the MDI. (MDM)

Examined genetic and environmental contribution to self-reported peer-group characteristics among adoptive and nonadoptive adolescent sibling pairs. Found that although peer preference is influenced, in large part, by nonshared environment factors, genetic influence is present. Substantial genetic influence emerged for college orientation, and…

Scarr and Weinberg's results (Intelligence, 1977) are compared to those of similar adoption studies and found to be quite similar, despite the transracial adoption patterns in Scarr and Weinberg's sample. The author also suggests that the major contribution of behavioral genetics to psychology may be our increased understanding of the environment.…

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.…

Explored aggression and delinquency in unrelated adoptive sibling pairs and biologically-related sibling pairs in the Colorado Adoption Project at 7, 9, 10, 11, and 12 years. Found that boys and adopted children were higher in externalizing behavior problems than girls and biologically related pairs. Sex differences in delinquency were more…

This chapter argues for the value of sibling research in addressing behavioral genetic issues on the etiology of individual differences. The goal of the report is to provide a set of simple and practical examples of sibling analyses in order to highlight the importance of incorporating siblings in future research. It begins with a discussion of…

Focuses on possibility that correlations between measures of environment and child devleopment can be mediated genetically as well as environmentally. Proposing an elementary model to test this hypothesis, data from classical adoption studies and new data from the Colorado Adoption Project are used to illustrate the model and provide quantitative…

Language development was studied in 310 pairs of 4-year-old twins. Rotated factor analyses indicated presence of a general language factor (L) and a general nonverbal factor (NV). Moderate genetic influence was found for L and NV abilities. Bivariate genetic analysis estimated a genetic correlation of .63 between L and NV abilities. Results…

This study of 707 sibling pairs, 10- to 18-years-old, examined parent-child and sibling interactions to determine the effects of genetics on family environment. The sample included identical and fraternal twins and full siblings in nondivorced families, as well as full, half, and unrelated siblings in divorced families. Found significant genetic…

Outlines what developmentalists can do with genes associated with behavioral dimensions and disorders once they are found. Suggests that genes can be used to answer questions about developmental continuities, psychopathological patterns such as heterogeneity and comoribidty, and environmental-risk mechanisms informed by studies of gene/environment…

This behavioral genetic study examined perceived competence and self-worth in same-sex twins, siblings, and stepsiblings 10 to 18 years old, and again 3 years later. Findings at second assessment showed six of seven subscales heritable. Genetic contributions to stability were found for perceived scholastic competence, athletic competence, physical…

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)

Reviews research on the heritability of intellectual factors, personality factors, and psychopathology. Discusses the importance of investigating within-family environmental differences in order to understand the environmental origins of individual differences in development. (Author/BJV)