This article reviews sex studies of children of cousin marriages and three studies of children of incestuous matings. It is argued that these studies, taken as a whole, provide no substantial evidence for an inbreeding depression effect within the polygenic system commonly asserted to determine IQ. (Author/DB)

Explored genetic and environmental etiologies of individual differences in printed word recognition and related skills in identical and fraternal twin 8- to 18-year-olds. Found evidence for moderate genetic influences common between IQ, phoneme awareness, and word-reading skills and for stronger IQ-independent genetic influences that were common…

Posits that an evolutionary perspective can unite the study of the typical development for and individual variation within a species and that environments within the normal range for a species are required for species-normal development. Individual differences in children reared in normal environments arise primarily from genetic variation and…

Focuses on the integrity and ethics of Arthur Jensen, while tracing the negative reactions his work on genetic differences in intelligence has evoked. Outlines some other areas in which Jensen has worked and commends his emphasis on honest psychological science. (SLD)

The Flynn effect, documented by a New Zealand political scientist, refers to the fact that average IQ scores have been increasing over time, reflecting the effects of environmental factors. Implications for the measurement of the intelligence of African American children and their educations are discussed. (SLD)

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…

Examines contemporary research on parental socialization. Highlights research designs that consider inherited, dispositional, and experiential factors in estimating influence. Describes evidence addressing issues of causality regarding the scope and nature of parental influences. Recommends basing conclusions about the significance of parenting on…

Despite extensive research, questions underlying the nature and nurture of talent remain both numerous and diverse. In the current paper, we present an account that addresses 2 of the primary questions inspired by this debate: (a) the very existence of innate talents and (b) how exceptional abilities are developed. The development of exceptional…

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…

D. V. M. Bishop and M. J. Snowling (2004) proposed that 2 dimensions of language are required to conceptualize the relationship between dyslexia and specific language impairment: phonological skills and wider language skills beyond phonology (grammatical, semantic, and pragmatic skills). In this article, we discuss the commonalities between…

The author reexamines the controversy surrounding his genetic hypothesis in an attempt to clarify his contention that differences in IQ scores between blacks and whites may be attributable as much to heredity as environment. (EH)

Determinants of Schaefer's (1965) three dimensions of perceived parenting (Acceptance vs. Rejection, Psychological Control vs. Psychological Autonomy, and Firm vs. Lax Control) were investigated by administering a shortened Children's Reports of Parental Behavior Inventory to adolescent twins. The sample consisted of 46 pairs of identical twins…

A parent-offspring adoption path model, with a measured index of the home environment, was developed to assess extent to which genetic and environmental influences of the parents affect relationships between the environmental index and children's behavior. Intelligence Quotient (IQ) data from the Colorado Adoption Project were used. The…

The choice between genetic and environmental explanations is most properly based on "jointly genetic/environmental designs," which control for both genetic and environmental differences in a behavior genetic framework. (Author/GC)

Examined data from 408 pairs of identical, same-sex fraternal twins at 14, 20, and 24 months to assess cognitive development and to identify genetic and environmental influences on phenotypic similarity. Found various patterns of development for separate constructs, for females versus males on each construct, and for individuals across constructs.…