The current analysis investigates genetic and environmental influences on the bidirectional relationships between temperament and general cognitive ability (GCA). Measures of GCA and three temperament factors (persistence, approach, and reactivity) were collected from 486 children ages 4-9 years (80% white, 50% female) from the Louisville Twin…

Dysregulation of biological stress response, as measured by cortisol output, has been a primary candidate mechanism for how social experiences become biologically embedded. Cortisol is the primary output of the hypothalamic pituitary adrenal (HPA) axis. Cortisol levels vary systematically across the day and change in response to both sudden, acute…

We offer a new analysis of a large-scale trial of an early-childhood education program that targeted premature, low-birthweight children. This targeting heavily oversampled twins, whose outcomes differed significantly from singletons'. Singletons' gains in short-term cognition and age-18 non-cognitive skills were comparable to those of the Perry…

We compared dyad-focused maternal speech (protoconversations and maternal speech describing the dyad) in interactions of mothers with their twin and singleton infants. Nine twins and nine singletons, coming from urban areas of Crete (Greece), were video-recorded at home in spontaneous face-to-face interactions with their mothers, from the 2nd to…

Children's early vocabulary shows sex differences -- with boys having smaller vocabularies than age-comparable girls -- a pattern that becomes evident in both singletons and twins. Twins also use fewer words than their singleton peers. However, we know relatively less about sex differences in early gesturing in singletons or twins, and also how…

This study explored whether high autistic traits, high attention deficit hyperactivity disorder (ADHD) traits and their interaction were associated with quality of life (QoL) in a sample of 556 of young-adult twins (Mean age 22 years 5 months, 52% Female). Four participant groups were created: high autistic traits, high ADHD traits, high…

Digital Storytelling (DST) employs digital technology to enhance traditional storytelling by incorporating digital elements such as graphics, audio, video, and music. This study, grounded in sociocultural theory (SCT) and constructivism, investigated how DST contributes to and facilitates multi-literacy development and language skills among young…

Future orientation tends to prevent engagement in risk behaviours and results in good academic performance among adolescents. Our study aimed to establish whether genetic factors contributed to future orientation among Chinese adolescents. We recruited 988 pairs of twins from Beijing. By constructing a high-order A (additive genetic variance) C…

Background: Children's academic achievement is considerably influenced by genetic factors, which rarely operate independently of environmental influences such as teachers' behaviour. Praise and punitive discipline are commonly used management strategies by teachers. However, their effects on the genetic expression of children's academic…

Background: Creativity is linked with educationally relevant constructs such as achievement, intelligence, and motivation. However, very few studies have explored longitudinal links between the constructs or the aetiology of individual differences in childhood creativity. Aims: The study addresses the gap in the literature of developmental studies…

This study investigated the association between autism and self-reported eating problems and the influence of gender on the association, in a sample of adolescent and adult twins (N = 192). Autistic traits and autism diagnosis were associated with both total and specific eating problems, including selective eating and sensory sensitivity during…

There is increasing concern regarding additional psychiatric problems that co-occur with Autism Spectrum Disorder (ASD), as reflected in recent changes to diagnostic schemes. However, there remains little research with population-based samples across childhood. We report on additional problems, as measured by the Strengths and Difficulties…

Background: Educational attainment is connected to many important life outcomes, and the previous research has already focused on identifying its genetic and environmental components. However, most of these studies used twin data only and did not incorporate information from other family members. Twin studies typically decompose the phenotypic…

We compared maternal speech in interactions of mothers with their firstborn dizygotic twin and singleton infants. Nine twins and nine singletons were video-recorded at home in spontaneous face-to-face interactions with their mothers, from the 2nd to the 6th month. Continuous micro-analysis revealed that there are more quantitative and qualitative…

Purpose: Early language and speech acquisition can be delayed in twin children, a twinning effect that diminishes between 4 and 6 years of age in a population-based sample. The purposes of this study were to examine how twinning effects influence the identification of children with language impairments at 4 and 6 years of age, comparing children…