Naturalistic observation of a set of identical twins revealed many differences in personality and motor development. (MS)

Examines recent developments in the American debate over heredity and environment. (RM)

Describes a methodology of behavior genetics in the context of twin and sibling/adoption design. This model was applied to cross-sectional data on cognitive development throughout the lifespan. Results from a twin and adoption study of general intelligence are presented to illustrate the use of the basic behavior genetic model in studying causes…

Social scientists are often concerned that research on biological causes of behavior will encourage biologically-based public policy. By simultaneously examining both social and biological causes of behavior, biosocial research models prevent simplistic biological thinking. Concludes that biosocial models clarify ethical problems rather than…

This article reviews and critiques the research on possible genetic factors in stuttering. The failure to consider epidemiologic factors is thought to have biased previous research, but recent data provide evidence that spontaneous recovery and chronicity are influenced by genetic factors. Findings support previous conclusions about combined…

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…

Examined the effects of gender on academic achievement for 138 mono- and 125 dizygotic twin pairs, ranging in age from 6 to 12 years. Results suggested that individual differences in academic achievement may be more influenced by genetic than environmental variance in females, and by environmental than genetic variance in males. (BC)

This study examining children's understanding of biological inheritance addressed four central questions: (1) are young children able to distinguish between the relative influences of nature and nurture in their understanding of how physical characteristics versus behaviors and preferences develop in animals? (2) does children's understanding of…

Research has shown that differences among ordinary people in intelligence and personality depend equally on individual genetic variability and on differences in the environments that siblings experience within the same family, not differences in the neighborhood, school, and community environments. As of yet, there are no adequate theories to…

Reviews the furor and reaction to Arthur Jensen's controversial genetic theory of intellectual differences. The cases of Shockley, Eysenck, and Herrnstein are also discussed as instances in which intellectual debate was supplanted by academic persecution and impassioned rhetoric. (EH)

Intelligence tests were administered to a stratified sample of 4058 school children from Palermo, Sicily. I.Q. scores were found to be positively correlated with socioeconomic status and negatively related to family size. As birth order increased, mental development decreased. Implications for future research were discussed. (EH)

The estimation of genetic models reported by J. L. Jinks and L. J. Eaves in a recent review are critically examined. A number of errors in procedure and interpretation are found. It is concluded that the evidence, provided by kinship correlations, for the proposition that intelligence is highly heritable, is not persuasive. (Author/BJG)

Scores were obtained on 31 item-clusters from the California Psychological Inventory for 490 identical and 317 same-sex fraternal twin pairs from the National Merit twin sample. Ordinary and cross-pair correlations were calculated and used to derive three matrices hypothesized to reflect the influence of genes, shared environment, and unshared…

This paper reviews what is known about intelligence and the use of intelligence tests. Environmental and hereditary factors that affect performance on intelligence tests are reviewed, along with various theories that have been proposed about the basis of intelligence. Intelligence tests do not test intelligence per se but make inferences about a…

Accumulating empirical evidence documents the significant contribution of biological variables to the determination of social behaviors. More appropriate biosocial models may need to allow for causal relationships between biological and social determinants and for effects that are interactive, nonlinear, and discontinuous. Demographic surveys…