Strong Genetic Contribution to Peer Relationship Difficulties at School Entry: Findings From a Longitudinal Twin Study

Reconsidering the failure model: Using a genetically controlled design to assess the spread of problems from reactive aggression to internalizing symptoms through peer rejection across the primary school years

According to the failure model (Patterson & Capaldi, 1990), peer rejection is the intermediary link between problem behaviors and internalizing symptoms. The present study tested the model with 464 monozygotic and same-sex dizygotic twin pairs (234 female, 230 male dyads). Teacher-reported reactive aggression and internalizing symptoms, and peer-reported peer rejection were collected at ages 6, 7, and 10 (from 2001 to 2008). Support for the failure model emerged in conventional non-genetically controlled analyses, but not twin-difference score analyses (which remove shared environmental and genetic contributions). Univariate biometric models attributed minimal variance in failure model variables to shared environmental factors, suggesting that genetic factors play an important unacknowledged role in developmental pathways historically ascribed to nonshared experiences in the failure model.

Gene-Environment Interplay Linking Peer Victimization With Adolescents' Trajectories of Depressive Symptoms

OBJECTIVE

This study examined to what extent genetic and environmental factors explain-either additively or interactively with peer victimization-different trajectories of adolescents' depressive symptoms and whether genetic factors related to distinct trajectories are correlated with peer victimization.

METHOD

Participants included 902 twins (52% girls) who self-reported peer victimization and depressive symptoms in grades 6, 7, 8, 9, and 11.

RESULTS

Growth mixture modeling revealed 3 trajectories of depressive symptoms: low (69.2% of participants), increasing (19.5%), and high-decreasing-increasing (11.3%). Biometric modeling showed that, for both sexes, genetic factors explained roughly half (52.6%, 47.5%) of the probability of following either a low or an increasing trajectory. Genetic influences (41%) were also observed for the high-decreasing-increasing trajectory, albeit only for girls. Nonshared environmental influences explained the remaining variances, along with shared environmental influences (27%) on the high-decreasing-increasing trajectory. Only for the low and the increasing trajectories, nonshared environmental influences increased with more frequent peer victimization (b_low = 0.206, 95% CI [0.094, 0.325]; b_increasing = 0.246, 95% CI [0.143, 0.356]). Moreover, peer victimization was associated with a lower probability of a low trajectory and a higher probability of an increasing or high-decreasing-increasing trajectory, and these associations were mostly explained by common underlying genetic factors.

CONCLUSION

Youth expressing (partly inherited) depressive symptoms may be at risk of peer victimization. However, increasing depressive symptoms in victims may be mitigated by other environmental factors except for those who enter adolescence with already high levels of depressive symptoms.

Early temperamental and biological predictors of dimensions of social withdrawal in childhood

Social wariness and preference for solitude, two dimensions of social withdrawal, show unique associations with various socioemotional difficulties in childhood, including internalizing and peer problems. However, their early childhood predictors remain vastly undocumented. The present study aimed to examine whether early indicators of reactivity in situations of unfamiliarity such as behavioral inhibition, affect, and cortisol independently, or in interaction with emotion regulation as indexed by vagal tone, predict later social wariness and preference for solitude. Participants were 1209 children from the Quebec Newborn Twin Study. Vagal tone was assessed at 5 months, and behavioral inhibition, affect, and cortisol were assessed at 19 months in situations of unfamiliarity. Mothers, teachers, and peers evaluated social wariness and preference for solitude repeatedly from 4 to 10 years old. Findings show that three temperamental dimensions, social inhibition, nonsocial inhibition, and affect accounted for the variability in reactions to unfamiliarity. Behavioral inhibition to social unfamiliarity at 19 months predicted social wariness during the preschool years. Poor vagal regulation at 5 months exacerbated the risk associated with negative affect at 19 months to predict preference for solitude during the preschool years. Overall, results show that social wariness and preference for solitude may follow different developmental pathways.

A multi-informant and multi-polygenic approach to understanding predictors of peer victimisation in childhood and adolescence

Introduction

Peer victimisation is a prevalent occurrence in childhood and adolescence and can often have long-lasting consequences. Previous research using polygenic scores (PGSs) have revealed various genetic vulnerabilities as predictive of victimisation in childhood. However, findings were based on self-report and may therefore be influenced by varying self-perceptions. Previous investigations also focused on average victimisation across childhood, and thus do not capture variability in polygenic predictability over time. The present study, therefore, aimed to investigate associations between PGSs and victimisation using separate and combined reports from teachers and peers in childhood, as well as self-reports in later adolescence to explore trajectories of victimisation.

Methods

Data were derived from the Quebec Newborn Twin Study. Participants were assessed for victimisation using self-reports from 7 to 17 years and using teacher ratings and peer nominations between 7 and 10 years (n = 536). Ten PGSs related to mental health, cognitive abilities and physical traits were examined as possible predictors of victimisation using linear regressions and growth curve models.

Results

Findings revealed that PGSs associated with victimisation are consistent across informants, but to varying extent according to estimated effect sizes. Self-reported victimisation was predicted by PGSs related to mental health, while PGSs related to cognitive and physical traits had larger effect estimates when predicting teacher- and peer-reported victimisation. The PGS for educational attainment was consistently negatively associated with victimisation across informants, producing the largest effect estimates (β = -.104, 95% CI = -.169 to -.039) when predicting a multi-informant measure of victimisation. No PGS predicted changes in victimisation over time.

Conclusion

While the PGS for educational attainment is a robust predictor of victimisation, many PGSs are differentially associated with victimisation depending on the informant. Such findings highlight the need to pay close attention to the phenotypic assessment of victimisation, and show that using multiple informants can both strengthen and provide unique insight into how associations may occur.

Prospectively Predicting Adult Depressive Symptoms from Adolescent Peer Dysfunction: a Sibling Comparison Study

Previous studies have shown that peer dysfunction in adolescence predicts depression in adulthood, even when controlling for certain individual- and/or family-level characteristics. However, these studies have not controlled for numerous potential familial confounders, precluding causal inferences. The present study therefore used a sibling comparison design (i.e., comparing siblings within families) to test whether peer dysfunction (e.g., lack of friendships, victimization) in adolescence continues to predict depression in adulthood after accounting for unmeasured familial confounds and individual characteristics in adolescence. Participants’ (N = 85) dysfunction with peers was assessed in adolescence (M_age = 13.21, SD = 3.47) by self- and parent-report, and adult depressive symptoms were assessed up to five times, up to 38 years later. Multilevel modeling was used to examine the effect of adolescent peer dysfunction on adult depressive symptoms after adjusting for familial confounds and/or individual characteristics in adolescence (e.g., baseline depressive symptoms, dysfunctional relations with siblings/parents). Both self-reported (b = 1.28, p < 0.001) and parent-reported (b = 0.56, p = 0.032) adolescent peer dysfunction were associated with greater depressive symptom severity in adulthood in unadjusted models. Self-reported (but not parent-reported) adolescent peer dysfunction continued to predict adult depressive symptoms after controlling for familial confounding and measured covariates such as adolescent depressive symptoms and relations with siblings and parents (b = 1.06, p = 0.035). Although confidence intervals were wide and the potentially confounding effects of numerous individual-level factors were not ruled out, these findings provide preliminary evidence that perceived peer dysfunction in adolescence may be an unconfounded risk factor for depressive symptoms in adulthood.

Links between peer victimization, dating violence victimization and depression in adolescence: A genetically-informed study

OBJECTIVE

The current study aimed to test if individuals with inherent dispositions to depression-related cognitions and behaviors are more at risk of experiencing relational difficulties, such as peer victimization and dating violence victimization.

METHOD

This study used a genetically informed design with 806 twins (51.5% girls) to test 1) if at least part of the association between peer victimization in school and dating violence victimization in emerging adulthood can be explained by common underlying heritable factors. Participants provided repeated assessments of their peer victimization in school at ages 13 through 17, their depression symptoms at ages 13 through 19, as well as their victimization in dating relationships at age 19.

RESULTS

A Cholesky decomposition based on structural equation modeling supported the hypotheses. Specifically, the association between peer victimization and dating violence victimization was to a significant extent explained by common underlying genetic vulnerabilities that were associated with depression symptoms. No sex moderation was found.

CONCLUSIONS

The findings highlight the importance of addressing early indicators of vulnerability toward depression symptoms to prevent victimization by peers or dating partners.

Links Between Early Personal Characteristics, Longitudinal Profiles of Peer Victimization in School and Victimization in College or at Work

This study used a longitudinal design from age six through age 19 (N = 1206 (603 girls)) to examine the associations between anxious-withdrawal and reactive aggression during childhood, distinct profiles of peer victimization from kindergarten to grade 11 and victimization in college or at work in emerging adulthood. In particular, it was tested whether the predictive effect of personal characteristics on victimization in emerging adulthood would be mediated via chronic peer victimization experiences during the school years. Teachers evaluated children's personal characteristics, whereas peer nominations and self-reports were used to assess victimization. Control variables included sex, parent-reported harsh parenting and SES. Longitudinal latent profile analysis revealed four distinct profiles of peer victimization during the school years: Consistently-Low (39.7%), Low-Moderate (42.8%), High-Decreasing (8.8%) and High-Increasing-Decreasing (8.7%). A subsequent 3-step regression-based path analysis supported the mediation hypothesis - albeit differently for different profiles of peer victimization. Specifically, compared to a Consistently-Low profile of peer victimization in school, a High-Decreasing profile was predicted by reactive aggression, but not anxious-withdrawal. In contrast, a High-Increasing-Decreasing profile was predicted by reactive aggression and anxious-withdrawal. In turn, elevated peer victimization profiles were associated with higher levels of later victimization in college or at work. The indirect effects linking the childhood behaviors to later victimization in college or at work - via elevated peer victimization profiles during childhood and adolescence - were significant. These results highlight the need for tailored interventions to optimize reactively aggressive or anxious-withdrawn children's response strategies to challenging and potentially threatening peer interactions.

Peer victimisation during adolescence and its impact on wellbeing in adulthood: a prospective cohort study

Background

Peer victimisation is a common occurrence and has well-established links with a range of psychiatric problems in adulthood. Significantly less is known however, about how victimisation influences positive aspects of mental health such as wellbeing. The purpose of this study was therefore to assess for the first time, whether peer victimisation in adolescence is associated with adult wellbeing. We aimed to understand whether individuals who avoid a diagnosis of depression after victimisation, maintain good wellbeing in later life, and therefore display resilience.

Methods

Longitudinal data was taken from the Avon Longitudinal Study of Parents and Children, a prospective cohort study based in the UK. Peer victimisation was assessed at 13 years using a modified version of the bullying and friendship interview schedule, and wellbeing at age 23 using the Warwick-Edinburgh Mental Well-Being Scale. The presence or absence of depression was diagnosed using the Clinical Interview Schedule–Revised at 18 years. A series of logistic and linear regression analyses were used to explore relationships between peer victimisation, depression, and wellbeing, adjusting for potentially confounding individual and family factors.

Results

Just over 15% of victims of frequent bullying had a diagnosis of depression at age 18. Victimisation also had a significant impact on wellbeing, with a one-point increase in frequent victimisation associated with a 2.71-point (SE = 0.46, p < 0.001) decrease in wellbeing scores aged 23. This finding remained after adjustment for the mediating and moderating effects of depression, suggesting that the burden of victimisation extends beyond depression to impact wellbeing. Results therefore show that individuals who remain partially resilient by avoiding a diagnosis of depression after victimisation have significantly poorer wellbeing than their non-victimised counterparts.

Conclusion

Overall, our study demonstrates for the first time that victimisation during adolescence is a significant risk factor for not only the onset of depression, but also poor wellbeing in adulthood. Such findings highlight the importance of investigating both dimensions of mental health to understand the true burden of victimisation and subsequent resilience. In addition to the need for interventions that reduce the likelihood of depression following adolescent victimisation, efforts should also be made to promote good wellbeing.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-021-10198-w.

Genotype-environment correlation by intervention effects underlying middle childhood peer rejection and associations with adolescent marijuana use

Aggressive behavior in middle childhood can contribute to peer rejection, subsequently increasing risk for substance use in adolescence. However, the quality of peer relationships a child experiences can be associated with his or her genetic predisposition, a genotype-environment correlation (rGE). In addition, recent evidence indicates that psychosocial preventive interventions can buffer genetic predispositions for negative behavior. The current study examined associations between polygenic risk for aggression, aggressive behavior, and peer rejection from 8.5 to 10.5 years, and the subsequent influence of peer rejection on marijuana use in adolescence (n = 515; 256 control, 259 intervention). Associations were examined separately in control and intervention groups for children of families who participated in a randomized controlled trial of the family-based preventive intervention, the Family Check-Up . Using time-varying effect modeling (TVEM), polygenic risk for aggression was associated with peer rejection from approximately age 8.50 to 9.50 in the control group but no associations were present in the intervention group. Subsequent analyses showed peer rejection mediated the association between polygenic risk for aggression and adolescent marijuana use in the control group. The role of rGEs in middle childhood peer processes and implications for preventive intervention programs for adolescent substance use are discussed.

Children With Persistent Versus Transient Early Language Delay: Language, Academic, and Psychosocial Outcomes in Elementary School

Purpose The objective of this study was to compare children with persistent versus transient preschool language delay on language, academic, and psychosocial outcomes in elementary school. Method Children with persistent language delay (n = 30), transient language delay (n = 29), and no language delay (controls; n = 163) were identified from a population-based sample of twins. They were compared on language skills, academic achievement, and psychosocial adjustment in kindergarten and Grades 1, 3, 4, and 6. Results Children with persistent language delay continued to show language difficulties throughout elementary school. Furthermore, they had academic difficulties, in numeracy, and psychosocial difficulties (attention-deficit/hyperactivity disorder behaviors, externalizing behaviors, peer difficulties) from Grade 1 to Grade 6. Children with transient language delay did not differ from controls on language and academic performance. However, they showed more externalizing behaviors in kindergarten and peer difficulties in Grade 1 than controls. Conclusion Difficulties at school age are widespread and enduring in those with persistent early language delay but appear specific to psychosocial adjustment in those with transient language delay.

Victimization by Friends and Victimization by Other Peers: Common Risk Factors or Mutual Influence?

Much research effort has been placed on understanding peer victimization. However, few studies have focused on victimization within friendships, which affects up to half of adolescents and bears similar consequences as victimization by the larger peer group. This study examined the temporal stability and the risk factors of victimization within friendships and victimization by other peers. In regard to the first objective, moderate to high levels of stability over a one-year period were expected for victimization by friends and by other peers. In regard to the second objective, two - not necessarily mutual exclusive - hypotheses were tested. The Common Risk Factors Hypothesis postulated that victimization by friends and by other peers share common personal and familial risk factors. Alternatively, the Mutual Influence Hypothesis proposed that victimization within one relationship context may increase the risk of being victimized in the other relationship context. These hypotheses were tested with a sample of 878 adolescents (Mage = 15.08 years, range 14.50-15.75; 52% female) assessed in Grades 8 and 9. Structural equation modeling revealed moderate and weak one-year stability for victimization by friends and by other peers, respectively. No common risk factors emerged, but victimization within one relationship context increased the risk of victimization in the other relationship context one year later. These results are in line with the mutual influence hypothesis and provide evidence of a cross-context transfer of victimization in adolescence.

Early Childhood Factors Associated With Peer Victimization Trajectories From 6 to 17 Years of Age

OBJECTIVES

To describe (1) the developmental trajectories of peer victimization from 6 to 17 years of age and (2) the early childhood behaviors and family characteristics associated with the trajectories.

METHODS

We used data from 1760 children enrolled in the Quebec Longitudinal Study of Child Development, a population-based birth cohort. Participants self-reported peer victimization at ages 6, 7, 8, 10, 12, 13, 15, and 17 years. Participants' behavior and family characteristics were measured repeatedly between ages 5 months and 5 years.

RESULTS

We identified 4 trajectories of peer victimization from 6 to 17 years of age: low (32.9%), moderate-emerging (29.8%), childhood-limited (26.2%), and high-chronic (11.1%). Compared with children in the low peer victimization trajectory, children in the other 3 trajectories were more likely to exhibit externalizing behaviors in early childhood, and those in the high-chronic and moderate-emerging trajectories were more likely to be male. Paternal history of antisocial behavior was associated with moderate-emerging (odds ratio [OR] = 1.54; 95% confidence interval [CI] = 1.09-2.19) and high-chronic (OR = 1.93; 95% CI = 1.25-2.99) relative to low peer victimization. Living in a nonintact family in early childhood was associated with childhood-limited (OR = 1.48; 95% CI = 1.11-1.97) and high-chronic (OR = 1.59; 95% CI = 1.09-2.31) relative to low peer victimization.

CONCLUSIONS

Early childhood externalizing behaviors and family vulnerabilities were associated with the development of peer victimization. Some children entered the cascade of persistent peer victimization at the beginning of primary school. Support to these children and their families early in life should be an important component of peer victimization preventive interventions.

Heritability of Bullying and Victimization in Children and Adolescents: Moderation by the KiVa Antibullying Program

Objective: Bullying affects approximately a quarter of schoolchildren and is associated with numerous adverse outcomes. Although distinct risk factors for bullying and victimization have been identified, few studies have investigated the genetic and environmental underpinnings of bullying and victimization. The aims of this study were twofold: first, to examine the contributions of genetic and environmental factors to bullying and victimization, and second, to analyze whether the KiVa antibullying program moderated the magnitude of these contributions by comparing estimates derived from the KiVa versus control groups.Method: The sample comprised students from schools that participated in the evaluation of the KiVa antibullying program in Finland during 2007-2009. Bullying and victimization were measured using peer nominations by classmates. The sample for the twin analyses comprised of 447 twins (107 monozygotic and 340 dizygotic twins) aged 7-15.Results: Genetic contributions accounted for 62% and 77% of the variance in bullying and in victimization at pre-intervention, respectively. There was a post-intervention difference in the overall role of genetic and environmental contributions between the intervention and the control group for bullying and victimization, with non-shared environmental effects playing a lesser role (and genes a larger role) in the intervention than in the control group context.Conclusions: This study replicates previous findings on the genetic underpinnings of both bullying and victimization, and indicates that a school-based antibullying program reduces the role of non-shared environmental factors in bullying and victimization. The results indicate that prevention and intervention efforts need to target both environmental and (heritable) individual level factors to maximize effectiveness.

The Quebec Newborn Twin Study at 21

This paper is a revised and updated edition of a previous description of the Quebec Newborn Twin Study (QNTS), an ongoing prospective longitudinal follow-up of a birth cohort of twins born between 1995 and 1998 in the greater Montreal area, Québec, Canada. The goal of QNTS is to document individual differences in the cognitive, behavioral, and social-emotional aspects of developmental health across childhood, their early genetic and environmental determinants, as well as their putative role in later social-emotional adjustment, school, health, and occupational outcomes. A total of 662 families of twins were initially assessed when the twins were aged 6 months. These twins and their family were then followed regularly. QNTS now has 16 waves of data collected or planned, including 5 in preschool. Over the last 24 years, a broad range of physiological, cognitive, behavioral, school, and health phenotypes were documented longitudinally through multi-informant and multimethod measurements. QNTS also entails extended and detailed multilevel assessments of proximal (e.g., parenting behaviors, peer relationships) and distal (e.g., family income) features of the child's environment. QNTS children and a subset of their parents have been genotyped, allowing for the computation of a variety of polygenic scores. This detailed longitudinal information makes QNTS uniquely suited for the study of the role of the early years and gene-environment transactions in development.

Associations between Oxytocin Receptor (OXTR) Genotype and Elementary School Children's Likability, Dis-likability and Friendship among Classroom Peers: A Longitudinal Study

The single nucleotide polymorphism rs53576 of the oxytocin receptor (OXTR) gene is involved in forming and maintaining relationships in various social contexts. However, this has not been studied in the childhood peer context. The present study followed 359 children (51.6% girls) from age 9 to 12 to explore associations between OXTR rs53576 genotype (i.e., AA, AG or GG genotype) and three indicators of children’s relationships with peers: likability and dis-likability among, and friendship with, classroom peers. Our results showed that OXTR rs53576 was associated with likability among boys, but not with dis-likability and friendship or among girls. Boys with an A and a G allele (i.e., AG genotype) became increasingly more liked by their peers across the four-year studied period than those with two A alleles or two G alleles (i.e., AA and GG genotype). This study indicates that OXTR rs53576 genotype might influence children’s peer relationships, particularly their likeability among peers. Associations between OXTR rs53576 and peer relationships may differ depending on children’s sex and the specific type of peer-relationship under scrutiny.

Causality and Pleiotropy in the Association Between Bullying Victimization in Adolescence and Depressive Episodes in Adulthood

Children and adolescents who are victims or perpetrators of bullying victimization are at elevated risk for maladjustment problems, concurrently and in the long run. Previous studies suggest that this correlation is partly explained by genetic influence. However, whether the genetic correlation is independent of a causal effect of victimization on maladjustment remains unclear. Using data from 2,510 females from the TwinsUK registry, we applied an innovative extension of the Cholesky decomposition to investigate to what extent the association between victimization in adolescence and self-reported depressive episodes in adulthood is caused by shared genetic effects (pleiotropy), and to what extent it is due to a phenotypic causal relationship. We find that around 60% of the association between victimization and self-reported depressive episodes is due to a causal effect of victimization on depressive episodes, and 40% is due to pleiotropic effects. These findings underline the importance of integrating genetic information into social science research and demonstrate a neat strategy to elucidate causal mechanisms in the absence of experimental designs.

Does cortisol moderate the environmental association between peer victimization and depression symptoms? A genetically informed twin study

Many youths who are victimized by peers suffer from depression symptoms. However, not all bullying victims show depression symptoms and individuals' biological sensitivity may play an important moderating role in this regard. In line with this notion, peer victimization has been associated with increased depressive symptoms in youth with higher basal cortisol secretion. It is unclear, however, whether this moderating effect of cortisol really concerns the environmental effect of peer victimization on depression. Indeed, genetic factors can also influence individuals' environmental experiences, including peer victimization, and part of these genetic factors may be those associated with depression. Using a genetically informed design based on 159 monozygotic and 120 dizygotic twin pairs (52% girls) assessed at age 14 years, this study examined whether cortisol secretion moderates the environmental or the genetic association between peer victimization and depression symptoms. Salivary cortisol at awakening was obtained with buccal swabs during four school week days. Peer victimization and depression were assessed via self-reports. Cholesky modeling revealed that peer victimization was associated with depression symptoms via both genetic and environmental pathways. Moreover, the environmental association between peer victimization and depression symptoms steadily increased with increasing levels of morning cortisol. The genetic association between peer victimization and depression symptoms also varied, albeit less, as a function of individuals' cortisol secretion. These findings support the hypothesis that peer victimization increases internalizing psychopathology mainly in youth with heightened biological reactivity to environmental conditions.

Victimization, Suicidal Ideation, and Alcohol Use From Age 13 to 15 Years: Support for the Self-Medication Model

PURPOSE

Recent years have seen increased coverage of adolescent victimization and suicide. Both adolescent peer victimization and substance use have been associated with suicidal ideation, with evidence suggesting that all three factors are interrelated. There are at least four models which can explain the associations between these factors (i.e., self-medication, secondary mental disorder, bidirectional, and common factor). However, none of them is being empirically supported as the dominant model because few longitudinal studies have explored the association between these factors.

METHODS

The present study compared longitudinal paths of all four models simultaneously using a cross-lagged model. This was done using self-reported measures of peer victimization, suicidal ideation, and alcohol use at age 13, 14, and 15 years in a longitudinal sample of 238 adolescents.

RESULTS

All three variables were moderately stable across time. Significant cross-lagged associations were found, showing that frequent peer victimization at age 13 years was associated with higher odds of having suicidal ideation at age 14 years (odds ratio, 1.82; p < .05). In turn, presence of suicidal ideation at age 14 years was significantly associated with higher alcohol use frequency at age 15 years (β = .13; p < .05).

CONCLUSIONS

Results support previous literature suggesting that peer victimization predates alcohol use and extends it by showing clear directionality between suicidal ideation and alcohol use over 1 year, supporting the self-medication model. Clarifying the empirical basis of these underlying models could allow for earlier prevention strategies, by targeting the risk factor that appears the earliest in the model.

Environmental influence of problematic social relationships on adolescents' daily cortisol secretion: a monozygotic twin-difference study

BACKGROUND

This study investigated the potential environmental effects of peer victimization and the quality of relationships with parents and friends on diurnal cortisol secretion in mid-adolescence.

METHOD

This study used the monozygotic (MZ) twin-difference design to control for genetic effects and thus estimate the unique environmental influences on diurnal cortisol. Participants were 136 MZ twin pairs (74 female pairs) for whom cortisol was assessed four times per day over four collection days grouped in a 2-week period in grade 8 (mean age = 14.07 years). Participants also provided self-reports of peer victimization from grade 4 to grade 8 and of the relationship quality with the mother, father and best friend in grade 8.

RESULTS

The expected pattern of diurnal cortisol secretion was observed, with high levels at awakening followed by an increase 30 min later and a progressive decrease subsequently. Controlling for a host of confounders, only within-twin pair differences in peer victimization and a problematic relationship with the mother were significantly linked to twin differences in diurnal cortisol secretion. Specifically, whereas a more problematic mother-child relationship was associated with morning cortisol secretion, peer victimization was linked to cortisol secretion later in the day (diurnal slope).

CONCLUSIONS

Controlling for genetic influences and other confounders, stressful relationships with peers and the mother exert unique and time-specific environmental influences on the pattern of diurnal cortisol secretion in mid-adolescence.

Temperament and peer problems from early to middle childhood: Gene-environment correlations with negative emotionality and sociability

Based in a transactional framework in which children's own characteristics and the social environment influence each other to produce individual differences in social adjustment, we investigated relationships between children's peer problems and their temperamental characteristics, using a longitudinal and genetically informed study of 939 pairs of Israeli twins followed from early to middle childhood (ages 3, 5, and 6.5). Peer problems were moderately stable within children over time, such that children who appeared to have more peer problems at age 3 tended to have also more peer problems at age 6.5. Children's temperament accounted for 10%-22% of the variance in their peer problems measured at the same age and for 2%-7% of the variance longitudinally. It is important that genetic factors accounted for the association between temperament and peer problems and were in line with a gene-environment correlation process, providing support for the proposal that biologically predisposed characteristics, particularly negative emotionality and sociability, have an influence on children's early experiences of peer problems. The results highlight the need for early and continuous interventions that are specifically tailored to address the interpersonal difficulties of children with particular temperamental profiles.

Considering the Genetic and Environmental Overlap Between Bullying Victimization, Delinquency, and Symptoms of Depression/Anxiety

Emerging evidence from longitudinal research suggests that bullied children are more likely to develop antisocial tendencies and mental health problems later in life. Less research, however, has used genetically sensitive research designs to control for genetic confounding and examine whether the well-supported association between bullying victimization and maladaptive development is partially accounted for by common genetic and environmental influences. Using sibling data from the National Longitudinal Survey of Youth 1997, the current study used a series of bivariate liability-threshold models to disentangle the genetic and environmental influences on observed covariance between repeated bullying victimization, delinquent involvement, and symptoms of depression/anxiety. Results revealed that common additive genetic and nonshared environmental effects accounted for the covariance in liability between bullying victimization and delinquent involvement as well as bullying victimization and symptoms of depression/anxiety. The results suggest the presence of genotype-environment correlation (rGE) between repeated victimization and maladaptive development.

Associations Between Sibling Relationship Quality and Friendship Quality in Early Adolescence: Looking at the Case of Twins

Bidirectional pathways between twin relationship quality and friendship quality were investigated in a large longitudinal twin cohort. We examined negative and positive relationship features in 313 monozygotic (MZ) twins and 238 same-sex dizygotic (DZ) twins from ages 13 to 14 years, using latent structural modeling. Results showed stronger stability of the twin relationship quality compared to friendship quality. Positive features in the sibling relationship were associated with increased positive features in the relationship with the best friend a year later. In contrast, no significant association between negative sibling relationship features and change in negative friendship quality features was found. These findings speak to the important role of the sibling relationship in the development of good quality friendship relations in twins.

Associations Between Peer Victimization and Suicidal Ideation and Suicide Attempt During Adolescence: Results From a Prospective Population-Based Birth Cohort

OBJECTIVE

To test whether adolescents who are victimized by peers are at heightened risk for suicidal ideation and suicide attempt, using both cross-sectional and prospective investigations.

METHOD

Participants are from the Quebec Longitudinal Study of Child Development, a general population sample of children born in Quebec in 1997 through 1998 and followed up until 15 years of age. Information about victimization and serious suicidal ideation and suicide attempt in the past year was obtained at ages 13 and 15 years from self-reports (N = 1,168).

RESULTS

Victims reported concurrently higher rates of suicidal ideation at age 13 years (11.6-14.7%) and suicide attempt at age 15 years (5.4-6.8%) compared to those who had not been victimized (2.7-4.1% for suicidal ideation and 1.6-1.9% for suicide attempt). Being victimized by peers at 13 years predicted suicidal ideation (odds ratio [OR] = 2.27; 95% CI = 1.25-4.12) and suicide attempt (OR = 3.05, 95% CI = 1.36-6.82) 2 years later, even after adjusting for baseline suicidality and mental health problems and a series of confounders (socioeconomic status, intelligence, family's functioning and structure, hostile-reactive parenting, maternal lifetime suicidal ideation/suicide attempt). Those who were victimized at both 13 and 15 years had the highest risk of suicidal ideation (OR = 5.41, 95% CI = 2.53-11.53) and suicide attempt (OR = 5.85, 95% CI = 2.12-16.18) at 15 years.

CONCLUSION

Victimization is associated with an increased risk of suicidal ideation and suicide attempt over and above concurrent suicidality and prior mental health problems. The longer the history of victimization, the greater the risk.

Parenting begets parenting: A neurobiological perspective on early adversity and the transmission of parenting styles across generations

The developing brains of young children are highly sensitive to input from their social environment. Nurturing social experience during this time promotes the acquisition of social and cognitive skills and emotional competencies. However, many young children are confronted with obstacles to healthy development, including poverty, inappropriate care, and violence, and their enhanced sensitivity to the social environment means that they are highly susceptible to these adverse childhood experiences. One source of social adversity in early life can stem from parenting that is harsh, inconsistent, non-sensitive or hostile. Parenting is considered to be the cornerstone of early socio-emotional development and an adverse parenting style is associated with adjustment problems and a higher risk of developing mood and behavioral disorders. Importantly, there is a growing literature showing that an important predictor of parenting behavior is how parents, especially mothers, were parented themselves. In this review, we examine how adversity in early-life affects mothering behavior in later-life and how these effects may be perpetuated inter-generationally. Relying on studies in humans and animal models, we consider evidence for the intergenerational transmission of mothering styles. We then describe the psychological underpinnings of mothering, including responsiveness to young, executive function and affect, as well as the physiological mediators of mothering behavior, including hormones, brain regions and neurotransmitters, and we consider how development in these relevant domains may be affected by adversity experienced in early life. Finally, we explore how genes and early experience interact to predict mothering behavior, including the involvement of epigenetic mechanisms. Understanding how adverse parenting begets adverse parenting in the next generation is critical for designing interventions aimed at preventing this intergenerational cycle of early adversity.

Genetic influences can protect against unresponsive parenting in the prediction of child social competence

Although social competence in children has been linked to the quality of parenting, prior research has typically not accounted for genetic similarities between parents and children, or for interactions between environmental (i.e., parental) and genetic influences. In this article, the possibility of a Gene x Environment (G × E) interaction in the prediction of social competence in school-age children is evaluated. Using a longitudinal, multimethod data set from a sample of children adopted at birth (N = 361), a significant interaction was found between birth parent sociability and sensitive, responsive adoptive parenting when predicting child social competence at school entry (age 6), even when controlling for potential confounds. An analysis of the interaction revealed that genetic strengths can buffer the effects of unresponsive parenting.

A longitudinal twin study of physical aggression during early childhood: evidence for a developmentally dynamic genome

BACKGROUND

Physical aggression (PA) tends to have its onset in infancy and to increase rapidly in frequency. Very little is known about the genetic and environmental etiology of PA development during early childhood. We investigated the temporal pattern of genetic and environmental etiology of PA during this crucial developmental period.

METHOD

Participants were 667 twin pairs, including 254 monozygotic and 413 dizygotic pairs, from the ongoing longitudinal Quebec Newborn Twin Study. Maternal reports of PA were obtained from three waves of data at 20, 32 and 50 months. These reports were analysed using a biometric Cholesky decomposition and linear latent growth curve model.

RESULTS

The best-fitting Cholesky model revealed developmentally dynamic effects, mostly genetic attenuation and innovation. The contribution of genetic factors at 20 months substantially decreased over time, while new genetic effects appeared later on. The linear latent growth curve model revealed a significant moderate increase in PA from 20 to 50 months. Two separate sets of uncorrelated genetic factors accounted for the variation in initial level and growth rate. Non-shared and shared environments had no effect on the stability, initial status and growth rate in PA.

CONCLUSIONS

Genetic factors underlie PA frequency and stability during early childhood; they are also responsible for initial status and growth rate in PA. The contribution of shared environment is modest, and perhaps limited, as it appears only at 50 months. Future research should investigate the complex nature of these dynamic genetic factors through genetic-environment correlation (r GE) and interaction (G×E) analyses.

Family histories of school bullying: implications for parent-child psychotherapy

OBJECTIVE

The purpose of this study was to determine whether a parent's past history of peer victimisation predicted their children's risk of being bullied at school.

METHOD

In face-to-face interviews, a representative community sample of 1895 mothers and fathers were asked about exposure to traumatic bullying during their schooling. Parents completed the Medical Outcomes Study Short-Form Health Survey (SF-36) to measure possible links with health-related quality of life. The interviews also inquired whether their children were victims of traumatic bullying at school.

RESULTS

Parental victimisation was associated with an increased risk for their children being bullied (55% with a positive parental history compared with 25% with no parental history: relative risk=2.17). In a multivariate logistic model controlling for the parents' age, gender, socioeconomic status and health-related quality of life (physical and emotional components), parental victimisation remained a strong predictor for the children's victimisation at school (relative risk=2.00). In 9.3% of the sample, both parent and child experienced bullying during their schooling.

CONCLUSIONS

Parent and child dyads can be exposed sequentially to school bullying. In some instances, they may share familial characteristics that are exploited by bullies. These experiences can be explored in parent-child psychotherapy.

Adoptive parent hostility and children's peer behavior problems: examining the role of genetically informed child attributes on adoptive parent behavior

Socially disruptive behavior during peer interactions in early childhood is detrimental to children's social, emotional, and academic development. Few studies have investigated the developmental underpinnings of children's socially disruptive behavior using genetically sensitive research designs that allow examination of parent-on-child and child-on-parent (evocative genotype-environment correlation [rGE]) effects when examining family process and child outcome associations. Using an adoption-at-birth design, the present study controlled for passive genotype-environment correlation and directly examined evocative rGE while examining the associations between family processes and children's peer behavior. Specifically, the present study examined the evocative effect of genetic influences underlying toddler low social motivation on mother-child and father-child hostility and the subsequent influence of parent hostility on disruptive peer behavior during the preschool period. Participants were 316 linked triads of birth mothers, adoptive parents, and adopted children. Path analysis showed that birth mother low behavioral motivation predicted toddler low social motivation, which predicted both adoptive mother-child and father-child hostility, suggesting the presence of an evocative genotype-environment association. In addition, both mother-child and father-child hostility predicted children's later disruptive peer behavior. Results highlight the importance of considering genetically influenced child attributes on parental hostility that in turn links to later child social behavior. Implications for intervention programs focusing on early family processes and the precursors of disrupted child social development are discussed.