@article {274, title = {Aggressive behaviour in childhood and adolescence: the role of smoking during pregnancy, evidence from four twin cohorts in the EU-ACTION consortium}, journal = {Psychological Medicine}, year = {2018}, pages = {1{\textendash}9}, abstract = {

BACKGROUND:

Maternal smoking during pregnancy (MSDP) has been linked to offspring\&$\#$39;s externalizing problems. It has been argued that socio-demographic factors (e.g. maternal age and education), co-occurring environmental risk factors, or pleiotropic genetic effects may account for the association between MSDP and later outcomes. This study provides a comprehensive investigation of the association between MSDP and a single harmonized component of externalizing: aggressive behaviour, measured throughout childhood and adolescence.

METHODS:

Data came from four prospective twin cohorts - Twins Early Development Study, Netherlands Twin Register, Childhood and Adolescent Twin Study of Sweden, and FinnTwin12 study - who collaborate in the EU-ACTION consortium. Data from 30 708 unrelated individuals were analysed. Based on item level data, a harmonized measure of aggression was created at ages 9-10; 12; 14-15 and 16-18.

RESULTS:

MSDP predicted aggression in childhood and adolescence. A meta-analysis across the four samples found the independent effect of MSDP to be 0.4\% (r = 0.066), this remained consistent when analyses were performed separately by sex. All other perinatal factors combined explained 1.1\% of the variance in aggression across all ages and samples (r = 0.112). Paternal smoking and aggressive parenting strategies did not account for the MSDP-aggression association, consistent with the hypothesis of a small direct link between MSDP and aggression.

CONCLUSIONS:

Perinatal factors, including MSDP, account for a small portion of the variance in aggression in childhood and adolescence. Later experiences may play a greater role in shaping adolescents\&$\#$39; aggressive behaviour.

}, doi = {10.1017/S0033291718001344}, author = {Malanchini, Margherita and Emily Smith-Woolley and Ayorech, Ziada and Kaili Rimfeld and Eva Krapohl and Vuoksimaa, Eero and Korhonen, Tellervo and Meike Bartels and van Beijsterveldt, Toos C.E.M. and Richard J. Rose and et al.} } @article {280, title = {Developing SENSES: Student experience of non-shared environment scales}, journal = {PLOS ONE}, volume = {13}, year = {2018}, month = {09}, pages = {1-16}, abstract = {

Twin and adoption studies find that non-shared environmental (NSE) factors account for variance in most behavioural traits and offer an explanation for why genetically identical individuals differ. Using data from a qualitative hypothesis-generating study we designed a quantitative measure of pupils\’ non-shared experiences at the end of formal compulsory education (SENSES: Student Experiences of Non-Shared Environment Scales). In Study 1 SENSES was administered to n = 117 16\–19 year old twin pairs. Exploratory Factor Analysis yielded a 49-item 10 factor solution which explained 63\% of the variance in responses. SENSES showed good internal consistency and convergent and divergent validity. In Study 2 this factor structure was confirmed with data from n = 926 twin pairs and external validity was demonstrated via significant correlations between 9 SENSES factors and both public examination performance and life satisfaction. These studies lend preliminary support to SENSES but further research is required to confirm its psychometric properties; to assess whether individual differences in SENSES are explained by NSE effects; and to explore whether SENSES explains variance in achievement and wellbeing.

}, doi = {10.1371/journal.pone.0202543}, url = {https://doi.org/10.1371/journal.pone.0202543}, author = {Yerdelen, Sundus and Durksen, Tracy and Kaili Rimfeld and Robert Plomin and Asbury, Kathryn} } @article {259, title = {Differences in exam performance between pupils attending selective and non-selective schools mirror the genetic differences between them}, volume = {3}, year = {2018}, month = {2018/03/23}, pages = {3}, abstract = {

On average, students attending selective schools outperform their non-selective counterparts in national exams. These differences are often attributed to value added by the school, as well as factors schools use to select pupils, including ability, achievement and, in cases where schools charge tuition fees or are located in affluent areas, socioeconomic status. However, the possible role of DNA differences between students of different schools types has not yet been considered. We used a UK-representative sample of 4814 genotyped students to investigate exam performance at age 16 and genetic differences between students in three school types: state-funded, non-selective schools (\‘non-selective\’), state-funded, selective schools (\‘grammar\’) and private schools, which are selective (\‘private\’). We created a genome-wide polygenic score (GPS) derived from a genome-wide association study of years of education (EduYears). We found substantial mean genetic differences between students of different school types: students in non-selective schools had lower EduYears GPS compared to those in grammar (d\ =\ 0.41) and private schools (d\ =\ 0.37). Three times as many students in the top EduYears GPS decile went to a selective school compared to the bottom decile. These results were mirrored in the exam differences between school types. However, once we controlled for factors involved in pupil selection, there were no significant genetic differences between school types, and the variance in exam scores at age 16 explained by school type dropped from 7\% to \<1\%. These results show that genetic and exam differences between school types are primarily due to the heritable characteristics involved in pupil admission.

}, isbn = {2056-7936}, url = {https://doi.org/10.1038/s41539-018-0019-8}, author = {Emily Smith-Woolley and Pingault, Jean-Baptiste and Saskia Selzam and Kaili Rimfeld and Eva Krapohl and Sophie von Stumm and Asbury, Kathryn and Philip S. Dale and Young, Toby and Allen, Rebecca and Yulia Kovas and Robert Plomin} } @article {278, title = {The stability of educational achievement across school years is largely explained by genetic factors}, volume = {3}, year = {2018}, month = {2018/09/04}, pages = {16}, abstract = {

Little is known about the etiology of developmental change and continuity in educational achievement. Here, we study achievement from primary school to the end of compulsory education for 6000 twin pairs in the UK-representative Twins Early Development Study sample. Results showed that educational achievement is highly heritable across school years and across subjects studied at school (twin heritability ~60\%; SNP heritability ~30\%); achievement is highly stable (phenotypic correlations ~0.70 from ages 7 to 16). Twin analyses, applying simplex and common pathway models, showed that genetic factors accounted for most of this stability (70\%), even after controlling for intelligence (60\%). Shared environmental factors also contributed to the stability, while change was mostly accounted for by individual-specific environmental factors. Polygenic scores, derived from a genome-wide association analysis of adult years of education, also showed stable effects on school achievement. We conclude that the remarkable stability of achievement is largely driven genetically even after accounting for intelligence.

}, isbn = {2056-7936}, url = {https://doi.org/10.1038/s41539-018-0030-0}, author = {Kaili Rimfeld and Malanchini, Margherita and Eva Krapohl and Hannigan, Laurie J. and Philip S. Dale and Robert Plomin} } @article {199, title = {Predicting educational achievement from DNA}, journal = {Mol Psychiatry}, volume = {22}, year = {2017}, month = {2017/02//print}, pages = {267 - 272}, abstract = {

A genome-wide polygenic score (GPS), derived from a 2013 genome-wide association study (N=127,000), explained 2\% of the variance in total years of education (EduYears). In a follow-up study (N=329,000), a new EduYears GPS explains up to 4\%. Here, we tested the association between this latest EduYears GPS and educational achievement scores at ages 7, 12 and 16 in an independent sample of 5825 UK individuals. We found that EduYears GPS explained greater amounts of variance in educational achievement over time, up to 9\% at age 16, accounting for 15\% of the heritable variance. This is the strongest GPS prediction to date for quantitative behavioral traits. Individuals in the highest and lowest GPS septiles differed by a whole school grade at age 16. Furthermore, EduYears GPS was associated with general cognitive ability (~3.5\%) and family socioeconomic status (~7\%). There was no evidence of an interaction between EduYears GPS and family socioeconomic status on educational achievement or on general cognitive ability. These results are a harbinger of future widespread use of GPS to predict genetic risk and resilience in the social and behavioral sciences.

}, isbn = {1359-4184}, url = {http://dx.doi.org/10.1038/mp.2016.107}, author = {Saskia Selzam and Eva Krapohl and Sophie von Stumm and Paul F O{\textquoteright}Reilly and Kaili Rimfeld and Yulia Kovas and Philip S. Dale and Lee,J J and Robert Plomin} } @article {198, title = {Weak associations between pubertal development and psychiatric and behavioral problems}, journal = {Translational Psychiatry}, volume = {7}, year = {2017}, month = {2017/04/}, pages = {e1098 - }, abstract = {

Pubertal development has been associated with adverse outcomes throughout adolescence and adulthood. However, much of the previous literature has categorized outcome variables and pubertal timing measures for ease of mean difference or odds ratio interpretation. We use a UK-representative sample of over 5000 individuals drawn from the Twins Early Development Study to extend this literature by adopting an individual differences approach and emphasizing effect sizes. We investigate a variety of psychiatric and behavioral measures collected longitudinally at ages 11, 14 and 16, for multiple raters and for males and females separately. In addition, we use two measures of pubertal development: the Pubertal Development Scale at each age, as well as the age of menarche for girls. We found that pubertal development, however assessed, was linearly associated with a range of psychiatric and behavioral outcomes; however, the effect sizes of these associations were modest for both males and females with most correlations between \−0.10 and 0.10. Our systematic analysis of associations between pubertal development, and psychiatric and behavioral problems is the most comprehensive to date. The results showing linearity of the effects of pubertal development support an individual differences approach, treating both pubertal development and associated outcomes as continuous rather than categorical variables. We conclude that pubertal development explains little variance in psychiatric and behavioral outcomes (\<1\% on average). The small effect sizes indicate that the associations are weak and should not warrant major concern at least in non-clinical populations.

}, isbn = {2158-3188}, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5416703/}, author = {Emily Smith-Woolley and Kaili Rimfeld and Robert Plomin} } @article {195, title = {Rotation is visualisation, 3D is 2D: using a novel measure to investigate the genetics of spatial ability}, journal = {Scientific Reports}, volume = {6}, year = {2016}, month = {2016}, pages = {30545}, abstract = {

Spatial abilities\–defined broadly as the capacity to manipulate mental representations of objects and the relations between them\–have been studied widely, but with little agreement reached concerning their nature or structure. Two major putative spatial abilities are \“mental rotation\” (rotating mental models) and \“visualisation\” (complex manipulations, such as identifying objects from incomplete information), but inconsistent findings have been presented regarding their relationship to one another. Similarly inconsistent findings have been reported for the relationship between two- and three-dimensional stimuli. Behavioural genetic methods offer a largely untapped means to investigate such relationships. 1,265 twin pairs from the Twins Early Development Study completed the novel \“Bricks\” test battery, designed to tap these abilities in isolation. The results suggest substantial genetic influence unique to spatial ability as a whole, but indicate that dissociations between the more specific constructs (rotation and visualisation, in 2D and 3D) disappear when tested under identical conditions: they are highly correlated phenotypically, perfectly correlated genetically (indicating that the same genetic influences underpin performance), and are related similarly to other abilities. This has important implications for the structure of spatial ability, suggesting that the proliferation of apparent sub-domains may sometimes reflect idiosyncratic tasks rather than meaningful dissociations.

}, isbn = {2045-2322}, url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4967849/}, author = {Shakeshaft, Nicholas G and Kaili Rimfeld and Schofield, Kerry L and Saskia Selzam and Malanchini, Margherita and Rodic, Maja and Yulia Kovas and Robert Plomin} }