Presents a study, using questionnaires, that defines and describes a typology of the relational structures of child twins on the basis of their mothers' representations of their behavior at school and home. Focuses on the dependence on the co-twin and dominant/dominated relationship in the two environments. (CMK)

Objective: To examine gender differences in attention-deficit/hyperactivity disorder ("ADHD") symptom comorbidity with "oppositional defiant disorder", "conduct disorder", "separation anxiety disorder", "generalized anxiety disorder", speech therapy, and remedial reading in children. Method: From…

The moderating effect of maternal warmth on the association between low birth weight and children's attention-deficit/hyperactivity disorder (ADHD) symptoms and low IQ was studied in 2,232 twins. Half of 5-year-old children had low birth weights, below 2,500 g. Maternal warmth, a component of expressed emotion, was coded from mothers' audiotaped…

Objectives: Little is known about how genes influence the development of symptoms included in the DSM-IV subtypes of attention-deficit/hyperactivity disorder (ADHD) from childhood to adolescence. The aim of this study was to examine genetic influences contributing to the development of hyperactive-impulsive symptoms and inattentive symptoms of…

Background: A fundamental issue for child psychology concerns the origins of individual differences in early reading development. Method: A measure of word recognition, the Test of Word Reading Efficiency (TOWRE), was administered by telephone to a representative population sample of 3,909 same-sex and opposite-sex pairs of 7-year-old twins.…

Background: Psychopaths are not only antisocial, but also have a callous and unemotional personality profile. This article selectively reviews evidence that psychopathic personality traits are an important factor in understanding and predicting the development of persistent antisocial conduct. Cognitive neuroscience research and more tentative…

Background: Findings from family and twin-based studies of Attention Deficit/Hyperactivity Disorder (ADHD) have indicated that inattentive and combined subtypes cluster together among sibling pairs who both express ADHD symptoms. The current report examines the familial clustering of ADHD subtypes, defined according to latent class and DSM-IV…

The use of assisted reproductive technology is increasing rapidly. Research, although sparse, has resulted in inconsistent findings as to the developmental prognosis for infants conceived by assisted reproductive techniques such as in vitro fertilization and the use of fertility drugs. In the present study, the authors compared twins who were…

A pair of monozygotic twins discordant for symptoms of Asperger syndrome was evaluated at the age of 13.45 years using psychometric, morphometric, behavioural, and functional imaging methods. The lower-functioning twin had a smaller brain overall, a smaller right cerebellum, and a disproportionately large left frontal lobe, and manifested almost…

This study was a longitudinal examination (21 month follow-up) of language development in a pair of fraternal twins. One twin received a cochlear implant at age 20 months secondary to sensorineural hearing loss. The other twin had normal hearing. Data were obtained every 6 months following her initial cochlear implant stimulation. Both twins…

We report the first major genetic study of mild mental impairment. From a representative sample of 3,886 twins (1,314 monozygotic, 1,296 dizygotic same-sex, and 1,276 dizygotic opposite-sex), the lowest 5% were selected on a composite measure of verbal and nonverbal abilities assessed by parents when the twins were 2, 3, and 4 years of age. Twin…

This study uses a multitrait, multimethod (MTMM) approach to investigate the genetic and environmental etiologies of childhood deviant peer affiliation (DPA) and problem behavior (PROB). The variability of genetic and environmental estimates by agent and method is also examined. A total of 77 monozygotic and 72 dizygotic twin pairs and each twin's…

Based on an actual event, this case study focuses on problems associated with reproductive technologies. It tells the story of the "Jones" who, after in vitro fertilization, discovered that their fraternal twins were less similar in appearance than one would expect two brothers to be. Students work in teams to unravel the mystery using DNA…

To investigate differences in mothers' interaction patterns with their neonate twins based on birth order, relative size at birth, or gender, 37 neonate twins and their mothers were observed during the first 10 minutes of a feeding in a hospital nursery. Time-sampling recordings were made of maternal behaviors related to proximal stimulation,…

Four null hypotheses were formulated to test for relationships between pairs of identical and fraternal twins and their parents on measures of locus of control. Two additional hypotheses were formulated to test for differences between mean scores of identical and fraternal twins and scores of their parents on these same constructs. Twenty pairs of…