Feeling inhibited and socially not at ease is reflected in the trait social inhibition (SI). SI is associated with psychopathology that arises in young adulthood, such as anxiety. We aim for a better insight into the genetic and environmental contributions to SI across the life span, and as such examine their contributions to SI stability and…

School genetics is changing. Nowadays, students are more likely to be introduced to the idea that many characteristics of organisms, including those of humans, are not determined by the actions of just one or two genes but result from interactions between the products of many genes and the environments of each organism. This article asks whether…

Valid and reliable teacher ratings serve as the foundation for screening and assessment of youth with behavioral disorders and twin studies offer an opportunity to study those ratings. We conducted a meta-analysis of 15 empirical investigations of aggressive and rule-breaking behavior using teacher ratings in the context of a twin research design.…

In this article, it is argued that it makes sense to define and distinguish three levels of human intelligence: intelligence as genotypical potential, intelligence as actualised in environmental interaction, and intelligence as measured by tests (IQ). This raises the questions of what is meant by the term "intelligence as potential", and…

This study examines whether, and how, multiple risks in early childhood are associated with an increased likelihood of a poor language or literacy outcome in early adolescence. Using data from 210 participants in the longitudinal Twins Early Developmental Study, we focus on the following risk factors at age 4: family risk, and poor language,…

A significant number of students with learning disabilities encounter challenges in acquiring knowledge, particularly in mathematics. Nonetheless, having a disability or being disadvantaged is not a preference or decision made by these students - or more generally, by these individuals; rather, this label is assigned to them by the prevailing…

This study examined whether strong cognitive skills (i.e. vocabulary, rapid naming, verbal working memory [VWM], and processing speed [PS]) contributed to resilience in single-word reading skills in children at risk for reading difficulties because of low phonological awareness scores (PA). Promotive factors were identified by main effects and…

The goal of the present study was to replicate Burt et al. (2009) and Hou et al. (2013) findings by determining the contribution of peers' deviance to changes in participants' (monozygotic [MZ] twins') self-reported delinquency from mid- to late adolescence while controlling for possible gene-environment correlations (rGE) through the use of the…

The association between physical fitness and age-related differences in cognition and brain structure has been studied fairly extensively during development and aging, yet comparatively less in young adulthood. The current study examined 1,195 young adults aged 22 to 36 (54% female; 67% Caucasian) to better understand associations between physical…

Performance in everyday spatial orientation tasks (e.g., map reading and navigation) has been considered functionally separate from performance on more abstract object-based spatial abilities (e.g., mental rotation and visualization). However, few studies have examined the link between spatial orientation and object-based spatial skills, and even…

Empathy and executive functions (EFs) are multimodal constructs that enable individuals to cope with their environment. Both abilities develop throughout childhood and are known to contribute to social behavior and academic performance in young adolescents. Notably, mentalizing and EF activate shared frontotemporal brain areas, which in previous…

Eng and Chang Bunker (1811--1874) were conjoined twins of Chinese ethnicity born in Siam (today, Thailand). Before the Civil War, they toured the United States to exhibit themselves as a "human curiosity," a wonder of nature, their conjoined state documented by local doctors at each stop on their tours, and their exhibition touted as…

Identification of language disorders in children younger than 3 years remains challenging despite agreement that early intervention improves outcomes. This study of twin language and gesture development substantiated the twinning effect, an unexplained lag in expressive and receptive language seen in twins, for a group of 88, 16- to 18-month-old…

A growing evidence base supports early intensive behavioral intervention (EIBI) for young children with autism spectrum disorder. We have found only one study exploring the outcome of EIBI for children with Rett syndrome, which reported little effect. It suggested that future studies should employ more fine-grained outcome measures. We provided…

The ability to enact cognitive control under changing environmental demands is commonly studied using set-shifting paradigms. While the control processes required for task set reconfiguration (switch costs) have been studied extensively, less research has focused on the control required during task repetition in blocks containing multiple tasks as…