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Summary: Background: Living in single parent and blended families or as an only child—compared to living in two‐parent biological families or with siblings, respectively—is associated with a higher body mass index (BMI) in cross‐sectional studies. However, longitudinal research addressing the children's BMI in this context is scarce. Further, little is known about the association between family structure and metabolic health. Objectives: This study aimed at investigating the association between both aspects of family structure with BMI and a metabolic score (MetS). Methods: Cross‐sectional data from 7804 children participating in the European multi‐center I.Family study (2013/2014) and longitudinal data from 5621 children who also participated previously in the IDEFICS study (2007–2010) were used. Family structure was assessed by a detailed interview. BMI z‐score and the MetS were based on measured anthropometry, blood pressure, high‐density lipoprotein, blood glucose, and triglycerides. Linear regressions were performed to model associations between family structure with BMI and MetS. Results: Children from single‐parent families had higher BMI z‐scores in the cross‐sectional (β = 0.09, 95% confidence interval [CI]: 0.001 to 0.18) and longitudinal analyses compared to those from two‐parent families. Cross‐sectionally, the number of siblings was associated with lower BMI z‐scores (β = −0.07, 95% CI: −0.10 to −0.03) and lower MetS (β = −0.14, 95% CI: −0.26 to −0.01). Longitudinally, only children between baseline and follow‐up had higher BMI z‐scores at follow‐up (β = 0.07, 95% CI: 0.01 to 0.14) compared to stable siblings. Conclusion: Obesity prevention measures should focus on single‐parent households and families with an only child. [ABSTRACT FROM AUTHOR]

Background: To conduct a comprehensive assessment of the association between aggression and academic performance in compulsory education. Method: We studied aggression and academic performance in over 27,000 individuals from four European twin cohorts participating in the ACTION consortium (Aggression in Children: Unraveling gene‐environment interplay to inform Treatment and InterventiON strategies). Individual level data on aggression at ages 7–16 were assessed by three instruments (Achenbach System of Empirically Based Assessment, Multidimensional Peer Nomination Inventory, Strengths and Difficulties Questionnaire) including parental, teacher and self‐reports. Academic performance was measured with teacher‐rated grade point averages (ages 12–14) or standardized test scores (ages 12–16). Random effect meta‐analytical correlations with academic performance were estimated for parental ratings (in all four cohorts) and self‐ratings (in three cohorts). Results: All between‐family analyses indicated significant negative aggression–academic performance associations with correlations ranging from −.06 to −.33. Results were similar across different ages, instruments and raters and either with teacher‐rated grade point averages or standardized test scores as measures of academic performance. Meta‐analytical r's were −.20 and −.23 for parental and self‐ratings, respectively. In within‐family analyses of all twin pairs, the negative aggression–academic performance associations were statistically significant in 14 out of 17 analyses (r = −.17 for parental‐ and r = −.16 for self‐ratings). Separate analyses in monozygotic (r = −.07 for parental and self‐ratings), same‐sex dizygotic (r's = −.16 and −.17 for parental and self‐ratings) and opposite‐sex dizygotic (r's = −.21 and −.19 for parental and self‐ratings) twin pairs suggested partial confounding by genetic effects. Conclusions: There is a robust negative association between aggression and academic performance in compulsory education. Part of these associations were explained by shared genetic effects, but some evidence of a negative association between aggression and academic performance remained even in within‐family analyses of monozygotic twin pairs. [ABSTRACT FROM AUTHOR]

Background: There has been an increase in children growing up in non-traditional families, such as single-parent and blended families. Children from such families have a higher prevalence of obesity and poorer health outcomes, but research on the relationship with obesogenic behaviours is limited. Objectives: Therefore, the aim of this study was to investigate whether there are associations between family structures and obesogenic behaviours and related family rules in European children and adolescents. Methods: The sample included 7664 children (mean age ± SD: 10.9 ± 2.9) from 4923 families who were participants of the multi-centre I.Family study (2013/2014) conducted in 8 European countries. Family structure was assessed by a detailed interview on kinship and household. Obesogenic behaviours (screen time, sleep duration, consumption of sugar-sweetened beverages (SSBs)) and family rules (rules for computer and television, bedtime routine, availability of SSBs during meals) were determined by standardized questionnaires. Multilevel mixed-effects linear and logistic regression models were used to model the associations of family structure with obesogenic behaviours and family rules. Sex, age, parental education level, number of children and adults in the household and BMI z-score were covariates in the models. Two-parent biological families were set as the reference category. Results: Children from single-parent families were less likely to have family rules regarding screen time (OR: 0.62, 95% CI: 0.40–0.94, p = 0.026) with higher reported hours of screen time per week (β = 2.70 h/week, 95% CI: 1.39–4.00, p < 0.001). The frequency of weekly SSB consumption differed by family structure in a sex-specific manner: girls from single-parent (β = 3.19 frequency/week, 95% CI: 0.91–5.47, p = 0.006) and boys from blended/adoptive families (β = 3.01 frequency/week, 95% CI: 0.99–5.03, p = 0.004) consumed more SSBs. Sleep duration, bedtime routines and availability of SSBs during meals did not differ between children from these family structures. Parental education did not modify any of these associations. Conclusions: Parents in non-traditional family structures appear to experience more difficulties in restricting screen time and the intake of SSBs in their children than parents in traditional two-parent family structures. Our findings therefore suggest that additional support and effective strategies for parents in non-traditional families may help to reduce obesogenic behaviours in children from such family types. [ABSTRACT FROM AUTHOR]

Purpose: This prospective study explores high sensitivity C-reactive protein (hs-CRP) levels in relation to dietary patterns at two time points in European children.Methods: Out of the baseline sample of the IDEFICS study (n = 16,228), 4020 children, aged 2-9 years at baseline, with available hs-CRP levels and valid data from a food frequency questionnaire (FFQ) at baseline (T0) and 2 years later (T1) were included. K-means clustering algorithm based on the similarities between relative food consumption frequencies of the FFQ was applied. hs-CRP was dichotomized according to sex-specific cutoff points. Multilevel logistic regression was performed to assess the relationship between dietary patterns and hs-CRP adjusting for covariates.Results: Three consistent dietary patterns were found at T0 and T1: ‘animal protein and refined carbohydrate’, ‘sweet and processed’ and ‘healthy’. Children allocated to the ‘protein’ and ‘sweet and processed’ clusters at both time points had significantly higher odds of being in the highest category of hs-CRP (OR 1.47; 95% CI 1.03-2.09 for ‘animal protein and refined carbohydrate’ and OR 1.44; 95% CI 1.08-1.92 for ‘sweet and processed’) compared to the ‘healthy’ cluster. The odds remained significantly higher for the ‘sweet and processed’ pattern (OR 1.39; 95% CI 1.05-1.84) when covariates were included.Conclusions: A dietary pattern characterized by frequent consumption of sugar and processed products and infrequent consumption of vegetables and fruits over time was independently related with inflammation in European children. Efforts to improve the quality of the diet in childhood may prevent future diseases related with chronic inflammation. [ABSTRACT FROM AUTHOR]

Twin cohorts provide a unique advantage for investigations of the role of genetics and environment in the etiology of variation in common complex traits by reducing the variance due to environment, age, and cohort differences. The GenomEUtwin (http://www.genomeutwin.org) consortium consists of eight twin cohorts (Australian, Danish, Dutch, Finnish, Italian, Norwegian, Swedish, and United Kingdom) with the total resource of hundreds of thousands of twin pairs. We performed quantitative trait locus (QTL) analysis of one of the most heritable human complex traits, adult stature (body height) using genome-wide scans performed for 3,817 families (8,450 individuals) derived from twin cohorts from Australia, Denmark, Finland, Netherlands, Sweden, and United Kingdom with an approximate ten-centimorgan microsatellite marker map. The marker maps for different studies differed and they were combined and related to the sequence positions using software developed by us, which is publicly available (https://apps.bioinfo. helsinki.fi/software/cartographer.aspx). Variance component linkage analysis was performed with age, sex, and country of origin as covariates. The covariate adjusted heritability was 81% for stature in the pooled dataset. We found evidence for a major QTL for human stature on 8q21.3 (multipoint logarithm of the odds 3.28), and suggestive evidence for loci on Chromosomes X, 7, and 20. Some evidence of sex heterogeneity was found, however, no obvious female-specific QTLs emerged. Several cohorts contributed to the identified loci, suggesting an evolutionarily old genetic variant having effects on stature in European-based populations. To facilitate the genetic studies of stature we have also set up a website that lists all stature genome scans published and their most significant loci (http://www. genomeutwin.org/stature_gene_map.htm). [ABSTRACT FROM AUTHOR]