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This study compared the contribution of genes and environment to teacher-rated reactive and proactive aggression in 6-year-old twin pairs (172 pairs: 55 monozygotic girls, 48 monozygotic boys, 33 dizygotic girls, 36 dizygotic boys). Genetic effects accounted for 39% of the variance of reactive aggression and for 41% of the variance of proactive aggression. The remainder of the variance was explained by unique environmental effects. Genetic as well as unique environmental effects were significantly correlated across reactive and proactive aggression (genetic correlation = 0.87, environmental correlation = 0.34), but this overlap was largely due to a common underlying form of aggression (i.e., teacher-rated physical aggression). Once common etiological factors due to physical aggression were accounted for, reactive and proactive aggression shared no other genes and only a few environmental influences, although additional specific genetic and environmental effects were observed for both reactive and proactive aggression. These specific effects indicate that both reactive and proactive aggression may be influenced mostly by socialization experiences that are specific to each type of aggression and only to a very small degree by specific genes.

The goal of this study was to examine the links between difficult temperament (i.e., negative emotionality) and harsh parental discipline during toddlerhood, and reactive and proactive aggression in kindergarten. These links were assessed on a longitudinal population-based study of 1516 boys and girls followed longitudinally from the age of 17 months through the age of 72 months. Two possible models were tested to examine the interplay between negative emotionality and harsh parenting in predicting later reactive aggression compared to proactive aggression. The first was an additive model where both aspects make unique contributions in predicting later reactive aggression. The second model was an interactive model where harsh parenting exacerbates the link between negative emotionality and reactive aggression. Results showed a specific contribution of negative emotionality to reactive aggression. The results relative to harsh parenting are more mixed but nonetheless in line with developmental models stressing different pathways to reactive and proactive aggression.

Based on the notion that friendship may serve an important protective function against peer victimization, this study examined the moderating effect of reciprocal friends' prosociality on the link between a child's reactive aggression and victimization. The study also investigated whether a similar moderating effect could be found with respect to sibling's prosociality, given that sibling relationships have been found to provide social benefits comparable to friendships. These questions were addressed using a sample of 246 six-year-old twin pairs (246 boys and 246 girls). The results showed that a child's own reactive aggression uniquely contributed to the risk of victimization for both boys and girls. The link between reactive aggression and victimization was, however, moderated by reciprocal friends' prosocial behavior and siblings' prosocial behavior, respectively. The results are discussed in terms of their theoretical and prevention-related implications for children at risk for peer victimization.

Background: Given the importance of parenting for the child's early socio-emotional development, parenting perceptions and behaviours, and their correlates, should be assessed as early as possible in the child's life. The goals of the present study were 1) to confirm, in two parallel population-based samples, including a large sample of twins, the factor structure of a new self-administered questionnaire assessing both parents' specific parenting perceptions and behaviours toward their 5-month-old infants (i.e., parental self-efficacy, perceived parental impact, parental hostile-reactive behaviours and parental overprotection), 2) to identify the specific risk factors associated with the negative side of these parenting dimensions, 3) to document the genetic-environmental etiology of these parenting dimensions through the twin method. Methods: Parents (2,122 mothers and 1,829 fathers) of 5-month-old infants, and parents of 5-month-old infant twins (510 families) completed the questionnaire (28 items). The data were submitted to a series of confirmatory factor analyses. The contribution to parenting of a variety of risk factors was examined in the two samples using regression analyses. A series of quantitative genetic analyses were performed to quantify the different sources of variation in parenting. Results: A consistent factor structure was found across informants and across samples. There were significant mean differences in parenting between mothers and fathers, as well as between parents of twins and parents of singletons. A differentiated pattern of association with risk factors was found for each dimension of parenting. The twin analyses revealed that shared environment accounted for each parenting dimension. Maternal hostile-reactive behaviours were also moderately related to genetic factors in the child and this association was mainly mediated by the infant difficultness. Conclusions: The overall pattern of results was consistent with Belsky's (1984) view of parenting as multiply determined. The longitudinal follow-up of these families should provide the means for testing developmental models about the determinants and outcomes of these parenting dimensions.

Background: Peer victimization is associated with a wide range of mental health problems in youth, yet few studies described its association with mental health comorbidities. Methods: To test the association between peer victimization timing and intensity and mental health comorbidities, we used data from 1216 participants drawn from the Quebec Longitudinal Study of Child Development, a population-based birth cohort. Peer victimization was self-reported at ages 6–17 years, and modeled as four trajectory groups: low, childhood-limited, moderate adolescence-emerging, and high-chronic. The outcomes were the number and the type of co-occurring self-reported mental health problems at age 20 years. Associations were estimated using negative binomial and multinomial logistic regression models and adjusted for parent, family, and child characteristics using propensity score inverse probability weights. Results: Youth in all peer victimization groups had higher rates of co-occurring mental health problems and higher likelihood of comorbid internalizing-externalizing problems [odds ratios ranged from 2.06, 95% confidence interval (CI) 1.52–2.79 for childhood-limited to 4.34, 95% CI 3.15–5.98 for high-chronic victimization] compared to those in the low victimization group. The strength of these associations was highest for the high-chronic group, followed by moderate adolescence-emerging and childhood-limited groups. All groups also presented higher likelihood of internalizing-only problems relative to the low peer victimization group. Conclusions: Irrespective of timing and intensity, self-reported peer victimization was associated with mental health comorbidities in young adulthood, with the strongest associations observed for high-chronic peer victimization. Tackling peer victimization, especially when persistent over time, could play a role in reducing severe and complex mental health problems in youth. [ABSTRACT FROM AUTHOR]

Background: Peer victimisation has been associated with depressive symptoms during adolescence, however not all peer victimised adolescents will exhibit such symptoms. This study tested whether having a genetic predisposition to developing depression increased the risk of experiencing depressive symptoms in peer victimised youth. To date, no study has explored such gene–environment interaction using a polygenic risk score for depression (PRS‐depression) in the context of peer victimisation and depressive symptoms in adolescence. Methods: The sample included 748 participants born in 1997/98 from the Quebec Longitudinal Study of Child Development with genotype data and prospectively collected information on peer victimisation (12–13 years) obtained from both self‐ and teacher‐reports, as well as self‐reported depressive symptoms (15–17 years). The PRS‐depression was based on the genome‐wide association meta‐analysis of broad depression by Howard et al. (2019). Results: Self‐ and teacher‐reported peer victimisation in early adolescence were both associated with depressive symptoms in adolescence (β = 0.34, p <.001; β = 0.14, p =.001 respectively), and this association remained significant when accounting for PRS‐depression (β = 0.33, p <.001; β = 0.13, p =.002 respectively). PRS‐depression was independently associated with depressive symptoms, but there was no significant PRS‐depression by peer victimisation interaction (self‐reported and teacher‐reported). PRS‐depression was correlated with self‐reported, but not teacher‐reported, peer victimisation. Conclusions: Our findings suggested that a partial measure of an individual's genetic predisposition to depression, as measured by PRS‐depression, and being exposed to peer victimisation (self‐ and teacher‐reported) were independently associated with depressive symptoms in adolescence. Furthermore, PRS‐depression did not exacerbate the risk of depressive symptoms among adolescents who had been peer victimised. Lastly, we found evidence of a gene–environment correlation between PRS‐depression and self‐reported peer victimisation. Future studies are needed to replicate this finding and to further understand the role of genetic predispositions in experiencing depressive symptoms following peer victimisation. [ABSTRACT FROM AUTHOR]

Background: Children's academic achievement is considerably influenced by genetic factors, which rarely operate independently of environmental influences such as teachers' behaviour. Praise and punitive discipline are commonly used management strategies by teachers. However, their effects on the genetic expression of children's academic achievement are still unclear. Aims: This study examined potential gene–environment interactions in the associations between children's estimated genetic disposition for academic achievement and teachers' use of praise and punitive discipline in predicting academic achievement. Sample: The participants were 165 twin pairs in sixth grade (M = 12.1 years). Methods: Teachers reported on children's academic achievement, as well as on their own behaviour. Results: Multilevel regression analyses showed significant interactions between children's estimated genetic disposition for academic achievement and teachers' use of praise and punitive discipline, respectively, in predicting academic achievement. These interactions indicated an enhancement process, suggesting that genetically advantaged children are those most likely to benefit from regular praise and infrequent punishments from their teacher. Moreover, genetically advantaged children were not more (nor less) likely to receive praise or punishments than other students. However, students from underprivileged backgrounds were less likely to receive praise from their teachers. Conclusions: The results emphasize the importance of teachers' regular use of praise and infrequent punitive discipline to help genetically advantaged children reach their full potential. Future studies should investigate other protective factors of the school environment that might reduce the role of genetic influences that undermine disadvantaged youth's academic achievement. [ABSTRACT FROM AUTHOR]

We assessed the psychometric properties of the Social Behavior Questionnaire (SBQ), a 30-item questionnaire evaluating social (e.g., disruptive behaviors, bullying) and emotional problems (e.g., anxiety, depression) among children aged 3.5–12 years. Children (n = 1,950, 50.21% boys) were drawn from the Quebec Longitudinal Study of Child Development. Mothers reported the frequency with which children presented social and emotional behaviors from 3.5 to 8 years of age, and teachers from 6 to 12 years. We assessed internal structure using Confirmatory Factor Analysis, reliability using Cronbach's alpha, and convergent and discriminant validity using a multitrait-multimethod (MTMM) approach. The six-factor (emotional distress, withdrawal, impulsive/hyperactive/inattentive, disruptive behaviors, prosocial behaviors, and peer relationships difficulties) structure of the SBQ showed good fit from ages 3.5 to 12 years. Reliability estimates were good to excellent (alphas >.7), and MTMM showed good convergent and discriminant validity. Overall, the SBQ presented good psychometric properties with a large population-based sample aged 3.5–12 years. Further studies should assess its screening potential by investigating its convergent validity with diagnostic information. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to examine the associations between attachment state of mind and adjustment to college. A related aim was to examine the moderating role of attachment state of mind in the relation between parental control and school adjustment. One-hundred two college freshmen completed the Adult Attachment Interview and a measure of parental control. They also completed a measure of college adjustment at the very beginning and at the very end of their freshman year. The findings showed that pre-occupation with attachment is related to poor adjustment after 1 year in college and to a general deterioration in adjustment and in grades during the freshman year. Preoccupation with attachment also accentuates the negative relationbetween parental psychological control and social adjustment. Dismissing attachment tendencies were found to be unrelated to college adjustment.

This study examined the changes in children's social network and specific self-perceptions during the transition from elementary school to junior high school (JHS). The participants were 200 preadolescent children (104 girls, 96 boys). Children's self-perceptions (global self-worth, perceived academic competence, and perceived social acceptance) and social network characteristics (parents and peer-enacted support) were evaluated four consecutive times over a 2-year period. Despite a slight decrease in the size of children's social network after the transition, the passage into JHS had no negative impact on the quality and functional aspects of their relationships with parents and school friends. The school transition was instead associated with an intensification of supportive relationships with school friends. Children's perceived social acceptance also increased suddenly after the JHS transition, while children's perceived scholastic competence decreased simultaneously during that time. Children's general self-esteem was then observed to decline progressively over a longer period of time. (Contains 2 tables.)

Used a genetic design to investigate association between physical aggression and language development in 19-month-old twins. Found a modest but significant correlation between aggression and expressive vocabulary. Substantial heritability was found for physical aggression. Quantitative genetic modeling suggested that the correlation could not be explained by shared etiologies. Phenotype-to-phenotype models indicated that the covariation could be accounted for by a significant phenotypic path from expressive vocabulary to physical aggression. (Author/KB)

Evaluated contributions of birth status (gestational age and birthweight) and family adversity at birth and at age 7 to explain behavior problems at age 7. Found significant relationships between birth status and isolation, social withdrawal problems, social immaturity, and inattention. Family adversity at birth contributed to aggression reported by three sources whereas, at age 7, this index related only to parent-reported aggression and social immaturity. (Author/KB)

Two cohorts of same-sex twin pairs were assessed on grammar and vocabulary. Findings indicated that vocabulary and grammar correlated strongly at 2 and 3 years in both cohorts, with a consistently high genetic correlation between vocabulary and grammar at both ages. Findings suggest that the same genetic influences operate for vocabulary and grammar, a finding incompatible with traditional autonomy hypothesis. (Author/KB)