Etiology of high and low cognitive ability in adulthood was explored through multiple regression analysis of data from 302 pairs of Swedish twins (median age=65.6 years). Both high and low cognitive ability groups demonstrate significant group heritability, with shared rearing environment of relatively low importance. (SLD)

Describes the interdisciplinary research of Myrtle B. McGraw; examines the controversy about McGraw's concept of critical period; and assesses her impact on current research. McGraw contended that the overlapping phases involved in neuromuscular integration demonstrate that learning and maturation interact during development. (BC)

The claim that multiple-birth children use "twin language" was investigated by describing and comparing the phonological characteristics of the speech of 19 sets of multiple birth children (aged 2-4) and by measuring multiple-birth children's understanding of their twins' or triplets' context-free speech. Results indicated that multiple…

A blind child and her sighted twin sister were recorded at home once a month from 2;5 to 3;5, and their repetitions and routines were analyzed with respect to three dimensions. Results showed that the blind twin used routines and modified imitations and repetitions more frequently, and her use of modified repetitions increased during the study.…

Temperament of nine-month olds was assessed by means of questionnaires and two laboratory visits. Mothers' and fathers' agreement on questionnaire scales was low, and their factor structures differed. In laboratory measures, fearfulness and pleasure showed cross-situation generality, short-term stability, and convergence with questionnaire scales.…

Parents who were identical twins, fraternal twins, or adopted siblings completed questionnaires assessing attitudes toward parenting and specific parenting practices, the emotional atmosphere of the home, and parental personality. Model-fitting results implicated modest genetic effects on affect-related aspects of parenting, such as parental…

Objective: To determine treatment patterns for youth attention-deficit/hyperactivity disorder (ADHD) symptoms in a general population sample of 1,610 twins. Method: Twin pairs ages 7 to 17 years and parents ascertained from birth records in the state of Missouri were interviewed using the Missouri Assessment of Genetics Interview for Children…

Background: The purpose of this study was to determine a score on the Obsessive Compulsive Scale (OCS) from the Child Behavior Checklist (CBCL) to screen for obsessive compulsive disorder (OCD) in children and to rigorously test the specificity and sensitivity of a single cutpoint. Methods: A receiver operating characteristic (ROC) curve analysis…

Background: This study examined conduct disorder (CD) and major depression (MDD) in adolescents in relationship to parent-child conflict and psychopathology in their parents. Method: Participants were drawn from a population-based sample of twins and their families. Affected participants had lifetime diagnoses of CD and/or MDD; controls had no…

Non-shared environmental influence (NSE) has been found to account for around 50 percent of anxiety variance, but specific NSE factors have not been identified. Discordant monozygotic (MZ) twins can be used to generate relevant hypotheses because MZ discordance can be caused by NSE, but not by genes or shared environment. Of 1590 MZ pairs teacher…

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…

A self-report measure of conflict and aspects of warmth in the parent-child relationship was completed by 1,330 11-year-old twins, 1,176 of whom completed the inventory again 3 years later. On average, adolescents' perceptions of the quality of the parent-child relationship declined consistently and moderately between age 11 and age 14. Conflict…

Two types of behaviours shown in children--those reflecting social impairment and nonsocial obsessive repetitive behaviours--are central to defining and diagnosing autism spectrum disorders (ASDs). Parent and teacher data on social and nonsocial behaviours were obtained from a community sample of greater than 3000 7-year-old twin pairs. Social and…

We report findings based on analyses of self-reports of six common adolescent psychopathologies (attention deficit/hyperactivity disorder, ADHD; conduct disorder, CD; oppositional defiant disorder, ODD; generalized anxiety disorder, GAD; separation anxiety disorder, SAD; and major depressive disorder, MDD) in a sample of 1,162 male and female…

Grade 1 literacy skills of twin children in Australia (New South Wales) and the United States (Colorado) were explored in a genetically sensitive design (N = 319 pairs). Analyses indicated strong genetic influence on word and nonword identification, reading comprehension, and spelling. Rapid naming showed more modest, though reliable, genetic…