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Background: Hyperactivity and inattention, the symptoms of ADHD, are marked by high levels of heritability and intergenerational transmission. Two distinct pathways of genetic intergenerational transmission are distinguished: direct genetic transmission when parental genetic variants are passed to the child's genome and genetic nurture when the parental genetic background contributes to the child's outcomes through rearing environment. This study assessed genetic contributions to hyperactivity and inattention in childhood through these transmission pathways. Methods: The sample included 415 families from the Quebec Newborn Twin Study. Twins' hyperactivity and inattention were assessed in early childhood by parents and in primary school by teachers. The polygenic scores for ADHD (ADHD‐PGS) and educational attainment (EA‐PGS) were computed from twins' and parents' genotypes. A model of intergenerational transmission was developed to estimate (1) the contributions of parents' and children's PGS to the twins' ADHD symptoms and (2) whether these variances were explained by genetic transmission and/or genetic nurture. Results: ADHD‐PGS explained up to 1.6% of the variance of hyperactivity and inattention in early childhood and primary school. EA‐PGS predicted ADHD symptoms at both ages, explaining up to 1.6% of the variance in early childhood and up to 5.5% in primary school. Genetic transmission was the only significant transmission pathway of both PGS. The genetic nurture channeled through EA‐PGS explained up to 3.2% of the variance of inattention in primary school but this association was non‐significant. Conclusions: Genetic propensities to ADHD and education predicted ADHD symptoms in childhood, especially in primary school. Its intergenerational transmission was driven primarily by genetic variants passed to the child, rather than by environmentally mediated parental genetic effects. The model developed in this study can be leveraged in future research to investigate genetic transmission and genetic nurture while accounting for parental assortative mating. [ABSTRACT FROM AUTHOR]

Growing evidence suggests that children's participation in early childhood education and care (ECEC), especially center-based services, is associated with positive outcomes, particularly for children over one year of age and children of low socioeconomic backgrounds. This signals an important opportunity for reducing socioeconomic disparities in young children's development. Many western countries have adopted policies to encourage maternal employment, facilitate ECEC service use, or both, often focusing on disadvantaged families. Yet few studies to date have tested the impact of these policies for reducing socioeconomic selection into ECEC. This study integrates data from five cohorts of children living in different western, high-income countries (UK, USA, Netherlands, Canada, and Norway; total N = 21,437). We compare participation rates and socioeconomic selection into ECEC across the different policy contexts in infancy (5-9 months) and early childhood (36-41 months). Policy environments where parents had access to at least 6 months of paid maternity/parental leave had lower ECEC participation in infancy but higher participation in early childhood. Higher participation rates were also associated with universal ECEC subsidies (i.e., not targeted to low-income families). In general, low income, low maternal education and having more than one child were associated with reduced use of ECEC. Selection effects related to low income and number of children were reduced in countries with universal ECEC subsidies when out-of-pocket fees were income-adjusted or reduced for subsequent children, respectively. Most socioeconomic selection effects were reduced in Norway, the only country to invest more than 1% of its GDP into early childhood. Nevertheless, low maternal education was consistently associated with reduced use of ECEC services across all countries. Among families using services however, there were few selection effects for the type of ECEC setting (center-based vs. non-center-based), particularly in early childhood. In sum, this comparative study suggests wide variations in ECEC participation that can be linked to the policy context, and highlights key policy elements which may reduce socioeconomic disparities in ECEC use. [ABSTRACT FROM AUTHOR]

Disregard for rules, a key component of oppositional defiant and conduct disorders, is stable during early childhood. This study investigates for the first time the relative importance of genetic and environmental factors underlying this early developmental stability. Maternal reports of child disregard for rules were obtained at four time points from 20 to 64 months of age in a population-based twin sample (N = 597 twin pairs, including 238 monozygotic and 359 dizygotic pairs). Structural equation modeling was conducted using both variance-covariance and latent growth curve approaches. Genetic factors accounted for most of the stability in disregard for rules throughout early childhood. In contrast, most environmental effects were age specific. Developmental stability in early symptoms of disregard for rules is best explained by the stable action of genetic factors, suggesting that preventive interventions should take an intergenerational approach, targeting at-risk families as early as possible. [ABSTRACT FROM AUTHOR]

This study investigated the evolving relations between peer victimization and social/emotional difficulties in middle to late childhood. Peer assessments of peer victimization and social/emotional difficulties (aggressive behavior, social withdrawal, and emotional vulnerability) were collected over 4 years for 1,035 children attending Grades 3-6 and were analyzed via cross-lagged panels and trajectory analyses. All dimensions were highly stable and significantly related initially. Peer victimization became progressively less related to aggression and increasingly associated with withdrawal. Bidirectional contributions over 1-year periods were found between withdrawal and emotional vulnerability and victimization. Trajectory analyses revealed heterogeneity in peer victimization patterns, with a small group of children (4.5%) being extremely victimized and with another group (10%), less severely, but increasingly victimized over time. Compared to nonvictimized children, these children were generally more emotional and became less aggressive but more socially withdrawn over time. These small behavioral changes were not associated with decreases in victimization. [ABSTRACT FROM AUTHOR]

The present study documented in two distinct population-based samples the contribution of preschool fluid and crystallized cognitive abilities to school achievement in primary school and examined the mediating role of crystallized abilities in this sequence of predictive associations. In both samples, participants were assessed on the same cognitive abilities at 63 months (sample 1, n = 1072), and at 41 and 73 months (sample 2, n = 1583), and then with respect to their school achievement from grade 1 (7 years) to grade 6 (12 years). Preschool crystallized abilities were found to play a key role in predicting school achievement. They contributed substantially to school achievement in the early school years, but more modestly in the later years, due to the strong auto-regression of school achievement. They also mediated the association between fluid abilities and later school achievement in the early grades of school, with the former having modest direct contribution to the latter in the later grades. These findings are discussed regarding their implication for preventive interventions. [ABSTRACT FROM AUTHOR]

Background: Parental educational expectations have been associated with children’s educational attainment in a number of long-term longitudinal studies, but whether this relationship is causal has long been debated. The aims of this prospective study were twofold: 1) test whether low maternal educational expectations contributed to failure to graduate from high school; and 2) compare the results obtained using different strategies for accounting for confounding variables (i.e. multivariate regression and propensity score matching). Methodology/Principal Findings: The study sample included 1,279 participants from the Quebec Longitudinal Study of Kindergarten Children. Maternal educational expectations were assessed when the participants were aged 12 years. High school graduation – measuring educational attainment – was determined through the Quebec Ministry of Education when the participants were aged 22–23 years. Findings show that when using the most common statistical approach (i.e. multivariate regressions to adjust for a restricted set of potential confounders) the contribution of low maternal educational expectations to failure to graduate from high school was statistically significant. However, when using propensity score matching, the contribution of maternal expectations was reduced and remained statistically significant only for males. Conclusions/Significance: The results of this study are consistent with the possibility that the contribution of parental expectations to educational attainment is overestimated in the available literature. This may be explained by the use of a restricted range of potential confounding variables as well as the dearth of studies using appropriate statistical techniques and study designs in order to minimize confounding. Each of these techniques and designs, including propensity score matching, has its strengths and limitations: A more comprehensive understanding of the causal role of parental expectations will stem from a convergence of findings from studies using different techniques and designs. [ABSTRACT FROM AUTHOR]