Estimates of shared environmental influence on educational attainment (EA) using the Classical Twin Design (CTD) have been enlisted as genetically sensitive measures of unequal opportunity. However, key assumptions of the CTD appear violated for EA. In this study we compared CTD estimates of shared environmental influence on EA with estimates from…

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…

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…

Behavior genetic methods are useful for examining mechanisms underlying the interaction between genetic and family environmental factors of internalizing problem behavior (INT). Previous twin studies, however, have shown little consistency in interaction patterns, depending on type and operationalization of measured environments. The aim of the…

Both genes and the environment are important for individual differences in expertise, but little is known about gene-environment interactions underlying domain-specific achievement. Here we explored this issue in a large Swedish twin cohort (N = 6,610), using moderator modeling with musical expertise as a model domain. Specifically, we tested…

Twin studies have documented that parenting behavior is partly heritable, but it is unclear how parents' genetics shape their caregiving. Using tools of molecular genetics, the present study investigated this process by testing hypotheses about associations between a genome-wide polygenic score for educational attainment and parental caregiving in…

Purpose: Variability in the timing of infant developmental milestones is poorly understood. We used a twin analysis to estimate genetic and environmental influences on motor development and activity levels in infancy. Method: Data were from the Gemini Study, a twin birth cohort of 2,402 families with twins born in the United Kingdom in 2007.…

Identity formation is a key developmental task in adolescence. Although many adolescents in modern societies face issues of identity, there are substantial individual differences in identity exploration and commitment. Little is known about the origins of these individual differences. The current study investigated the genetic and environmental…

The aims of this study were to: (a) provide descriptive data of twins with physical difficulties among 120 Greek twins of preschool age; and (b) to investigate the impact of twins' health condition on parental perceptions towards twins' separation, closeness and friendship. The administration of School Policy for Twins and Higher Multiples…

Background: "Food fussiness" (FF) is the tendency to be highly selective about which foods one is willing to eat, and emerges in early childhood; "food neophobia" (FN) is a closely related characteristic but specifically refers to rejection of unfamiliar food. These behaviors are associated, but the extent to which their…

Previous studies have shown that environmental influences on school science performance increase in importance from primary to secondary school. Here we assess for the first time the relationship between the science-learning environment and science performance using a genetically sensitive approach to investigate the aetiology of this link. 3000…

Studies of adolescent or parent-based twins suggest that gene-environment correlation (rGE) is an important mechanism underlying parent-adolescent relationships. However, information on how parents' and children's genes and environments influence correlated parent "and" child behaviors is needed to distinguish types of rGE. The present…

We present one of the first behavior-genetic studies of individual differences in school students' levels of achievement in instructed second language acquisition (ISLA). We assessed these language abilities in Australian twin pairs (maximum N pairs = 251) by means of teacher ratings, class rankings, and self-ratings of proficiency, and used the…

Variability in achievement across learners is a hallmark of second language (L2) learning, especially in academic-based learning. The Twins Early Development Study (TEDS), based on a large, population-representative sample in the United Kingdom, provides the first opportunity to examine individual differences in second language achievement in a…

We investigated for the first time the genetic and environmental aetiology behind scientific achievement in primary school children, with a special focus on possible aetiological differences for boys and girls. For a representative community sample of 2,602 twin pairs assessed at age nine years, scientific achievement in school was rated by…