How specific is second language-learning ability? A twin study exploring the contributions of first language achievement and intelligence to second language achievement

Learning a second language is crucially important in an increasingly global society, yet surprisingly little is known about why individuals differ so substantially in second language (SL) achievement. We used the twin design to assess the nature, nurture and mediators of individual differences in SL achievement. For 6263 twin pairs, we analyzed scores from age 16 UK-wide standardized tests, the General Certificate of Secondary Education (GCSE). We estimated genetic and environmental influences on the variance of SL for specific languages, the links between SL and English and the extent to which the links between SL and English are explained by intelligence. All SL measures showed substantial heritability, although heritability was nonsignificantly lower for German (36%) than the other languages (53–62%). Multivariate genetic analyses indicated that a third of genetic influence in SL is shared with intelligence, a third with English independent of intelligence and a further third is unique to SL.     

The high heritability of educational achievement reflects many genetically influenced traits,not just intelligence

Because educational achievement at the end of compulsory schooling represents a major tipping point in life, understanding its causes and correlates is important for individual children, their families, and society. Here we identify the general ingredients of educational achievement using a multivariate design that goes beyond intelligence to consider a wide range of predictors, such as self-efficacy, personality, and behavior problems, to assess their independent and joint contributions to educational achievement. We use a genetically sensitive design to address the question of why educational achievement is so highly heritable. We focus on the results of a United Kingdom-wide examination, the General Certificate of Secondary Education (GCSE), which is administered at the end of compulsory education at age 16. GCSE scores were obtained for 13,306 twins at age 16, whom we also assessed contemporaneously on 83 scales that were condensed to nine broad psychological domains, including intelligence, self-efficacy, personality, well-being, and behavior problems. The mean of GCSE core subjects (English, mathematics, science) is more heritable (62%) than the nine predictor domains (35–58%). Each of the domains correlates significantly with GCSE results, and these correlations are largely mediated genetically. The main finding is that, although intelligence accounts for more of the heritability of GCSE than any other single domain, the other domains collectively account for about as much GCSE heritability as intelligence. Together with intelligence, these domains account for 75% of the heritability of GCSE. We conclude that the high heritability of educational achievement reflects many genetically influenced traits, not just intelligence.Education is one of society’s biggest and most expensive environmental interventions in children’s development, accounting for more than 6% of the gross domestic product in many countries (1). Differences among children in their educational achievement, especially culminating at the end of compulsory schooling, propel children on different lifelong pathways that affect higher education, occupation, and even health and mortality (1–4). Not only are differences in educational achievement important to society and to children as individuals, they are also a focal concern for parents (5, 6). For these reasons, it is important to understand the causes and correlates of differences among children in their educational achievement.Educational achievement refers to mastery of specific content, including knowledge and skills for subjects such as literacy, numeracy, and science. The word achievement, in contrast to ability, connotes accomplishments by dint of effort. It is often assumed that effort is relatively more environmentally influenced than ability and thus that differences between children in their educational achievement are environmental in origin, reflecting differences among classrooms, schools, and parents (7, 8). This assumption is reasonable because, for example, most children will not learn to read or do arithmetic unless they are taught. However, genetic research has shown that individual differences in educational achievement are substantially heritable (9–11). Indeed, we have shown that educational achievement is significantly more heritable than intelligence in the early school years (12). We have recently found high heritability (58%) for the results of a nationwide examination, the General Certificate of Secondary Education (GCSE), which is administered in the United Kingdom at the end of compulsory education at age 16 (13).The present study asks why individual differences in educational achievement at the end of compulsory education are so highly heritable, focusing on children’s characteristics. Most phenotypic studies of the correlates of educational achievement have investigated intelligence or working memory (14–16). Correlations between IQ and educational achievement range between 0.4 and 0.7 (17). However, dozens of other traits have also been shown to relate to educational achievement, such as self-efficacy and motivation (18–21), emotional intelligence (22–25), personality (26–29), prosocial behavior (5), well-being (30), goals (31), curiosity (32), beliefs about intelligence (33), self-efficacy (34), behavior problems (35, 36), health (37), and children’s perceptions of their home environment (38) and their school environment (39). These traits are intercorrelated, which suggests the need for multivariate studies that can consider their joint and separate contributions to educational achievement. However, few broad multivariate phenotypic studies have been reported, although several studies have included intelligence in addition to another variable in predicting educational achievement (28, 40, 41). Recently, a theoretical model that attempted to integrate research on predictors of educational achievement focused on intelligence, specific interests, and personality, especially intellectual curiosity and conscientiousness (42).Phenotypic correlations between such traits and educational achievement can be mediated genetically or environmentally, which is important because environmentally driven associations may be better targets for intervention. Relatively few studies have used genetically sensitive designs that can disentangle genetic and environmental sources of phenotypic correlations between children’s traits and their educational achievement. Genetically sensitive studies have largely focused on intelligence, consistently showing that the phenotypic correlation between intelligence and educational achievement is mediated genetically to a substantial extent (43–50). Only a handful of studies have considered genetic contributions to educational achievement from other traits in addition to intelligence, such as self-efficacy (51), motivation (52, 53), personality (54), behavior problems (55–58), and perceptions of home environment (59) and school environment (60). Because these behavioral traits are correlated with each other and with educational achievement, adding up their separate genetic contributions to educational achievement could exceed the heritability of educational achievement. Multivariate genetic research is needed that considers the joint and independent contributions of a wide range of predictors to the heritability of educational achievement, taking into account the intercorrelations among the predictors. The only example to date is a twin study of longitudinal stability of teachers’ grades at ages 11–17 for 800 pairs of twins that also reported multivariate genetic analyses, in which the heritability of teachers’ grades at age 11 were largely explained collectively by genetic factors involved in intelligence, engagement, and externalizing behavior problems (61). This report led us to hypothesize that the substantial heritability of test scores at the end of compulsory education could almost entirely be explained by a larger set of predictors that includes self-efficacy, personality, and well-being.     

Overview of CAPICE—Childhood and Adolescence Psychopathology: unravelling the complex etiology by a large Interdisciplinary Collaboration in Europe—an EU Marie Skłodowska-Curie International Training Network

European Child & Adolescent Psychiatry - The Roadmap for Mental Health and Wellbeing Research in Europe (ROAMER) identified child and adolescent mental illness as a priority area for research....     

Multivariate analyses of molecular genetic associations between childhood psychopathology and adult mood disorders and related traits

Ubiquitous associations have been detected between different types of childhood psychopathology and polygenic risk scores based on adult psychiatric disorders and related adult outcomes, indicating that genetic factors partly explain the association between childhood psychopathology and adult outcomes. However, these analyses in general do not take into account the correlations between the adult trait and disorder polygenic risk scores. This study aimed to further clarify the influence of genetic factors on associations between childhood psychopathology and adult outcomes by accounting for these correlations. Using a multivariate multivariable regression, we analyzed associations of childhood attention-deficit/hyperactivity disorder (ADHD), internalizing, and social problems, with polygenic scores (PGS) of adult disorders and traits including major depression, bipolar disorder, subjective well-being, neuroticism, insomnia, educational attainment, and body mass index (BMI), derived for 20,539 children aged 8.5–10.5 years. After correcting for correlations between the adult phenotypes, major depression PGS were associated with all three childhood traits, that is, ADHD, internalizing, and social problems. In addition, BMI PGS were associated with ADHD symptoms and social problems, while neuroticism PGS were only associated with internalizing problems and educational attainment PGS were only associated with ADHD symptoms. PGS of bipolar disorder, subjective well-being, and insomnia were not associated with any childhood traits. Our findings suggest that associations between childhood psychopathology and adult traits like insomnia and subjective well-being may be primarily driven by genetic factors that influence adult major depression. Additionally, specific childhood phenotypes are genetically associated with educational attainment, BMI and neuroticism.