The study examined the etiology of individual differences in early drawing and of its longitudinal association with school mathematics. Participants (N = 14,760), members of the Twins Early Development Study, were assessed on their ability to draw a human figure, including number of features, symmetry, and proportionality. Human figure drawing was…

The genetic effects on individual differences in reading development were examined using genome-wide complex trait analysis (GCTA) in a twin sample. In unrelated individuals (one twin per pair, n = 2,942), the GCTA-based heritability of reading fluency was ~20%-29% at ages 7 and 12. GCTA bivariate results showed that the phenotypic stability of…

Using a genetic design of 840 60-month-old twins, this study investigated the genetic and environmental contributions to (a) individual differences in four components of cognitive school readiness, (b) the general ability underlying these four components, and (c) the predictive association between school readiness and school achievement. Results…

The effects of appetitive controllability on behavioral and cortisol reactivity to novelty in 12 infant rhesus monkeys were studied. Surrogate-peer-reared infants had homecage access to food treats contingently via lever pressing ("master") or noncontingently ("yoked") for 12 weeks from postnatal month 2. Masters lever-pressed more, but did not…

In this study of the origins of individual differences in theory of mind (ToM), the Environmental Risk (E-Risk) Longitudinal Twin Study sample of 1,116 sixty-month-old twin pairs completed a comprehensive battery of ToM tasks. Individual differences in ToM were striking and strongly associated with verbal ability. Behavioral genetic models of the…

If human cognitive development advances through a series of broad and general stages, then the child's mind at any developmental point should seem consistent and similar across situations in its maturity level and general style. However, there appear to be factors and conditions that promote homogeneity and heterogeneity in the child's cognitive…

A path model of genetic and shared family environmental transmission was fitted to general cognitive ability data from 1-, 2-, 3-, and 4-year-old adopted and nonadopted children and their parents to assess the etiology of longitudinal stability from infancy to early childhood. (HOD)

Examined violent and nonviolent inner-city children's moral reasoning about violence in family and peer situations. All of the children condemned unprovoked violence. With provoked situations, the violent group focused more on the immorality of the provocation and perceived force akin to reciprocal justice, whereas the nonviolent group perceived…

The language development of monozygotic twins, same-sex dizygotic twins, siblings of monozygotic twins, and siblings of dizygotic twins, ages 3-17, was studied to estimate how much of the individual variation in children's language skills results from genetic factors and how much from environmental experience. (BRT)

This study examined the power of nonshared environment to differentiate adolescent monozygotic twin development and the extent to which this power varied across social structural contexts. Findings indicated that differences in maternal closeness, teacher bonding, and religious participation differentiated twins on emotional distress. Family…

Argues that extant research assessing relations between contextual factors and psychological disturbance has confused two different roles of context. Suggests that environmental factors are nonspecific stressors and elicit psychopathology, with specificity of expressed psychopathology governed by individual differences, and that context is…

Used a longitudinal sibling research design and a large, nationally representative sample of 15- to 22-year-old siblings to study shared and unshared environmental influences on delinquency. Although no unshared family environmental influences were found for sisters and mixed-sex siblings, they may have existed for brothers. Data suggested…

Examined influences on children's behavior problems in households defined by marital status and sibling relatedness. Found that genetic influences accounted for 81 to 94 percent of mean-level difference in behavior problems between two-parent/full sibling, and the mother-only/half sibling groups. Shared environmental influences accounted for 67 to…

Argues that an evolutionary account provides insight into developmental function and individual differences. Outlines some assumptions of evolutionary psychology related to development. Introduces the developmental systems approach, differential influence of natural selection at different points in ontogeny, and development of evolved…

Argues that an evolutionary perspective can unite the study of species-typical development and individual variation. Provides examples from the domains of personality, social, and intellectual development. Maintains that understanding the ways in which genes and environments work together helps developmentalists identify children who need…