Introduction to the Special Issue: The Interplay Between Genetic Factors and the Peer Environment in Explaining Children\u27s Social Adjustment

Virtually all aspects of human development are subject to both genetic (i.e., heritable) and environmental influences that conjointly shape developmental outcomes through various mechanisms of gene–environment interplay. This special issue presents new research examining how the peer environment works together with genetic factors to influence children’s and adolescents’ social development. To this end, three studies utilize a quantitative genetic approach, whereas two others use molecular genetic methodologies. Covering a wide age range from early childhood to early adulthood, the studies examine different processes of gene–environment correlation and gene–environment interaction while focusing on dyadic and group-based peer experiences (e.g., friendships, peer acceptance, and peer victimization) as well as on positive and negative aspects of social development (e.g., prosocial leadership and aggression). Overall, the findings from the studies in this special issue clearly illustrate that we need to consider how genetics and the peer environment effects work together if we are to gain a more complete picture of children’s and adolescents’ social development

School Social Relations and Child Development:Gene-Environment Interplay

In the past, most theoretical perspectives on human development have focused on environmental causes of differences between children, but the consensus today is that genetic and environmental factors interact and reciprocally influence each other through gene-environment interplay. Most of the prior research has focused on genetic factors working together with family-related factors (e.g., socioeconomic status, parenting) or stressful life events and experiences (e.g., maltreatment) to explain differences in developmental outcomes. However, children spend many hours in educational settings interacting with peers and teachers who also can influence developmental adjustment and well-being. This chapter summarizes current knowledge about gene-and-school environment interplay among primary school-aged children through 12 years old (the average age that they transition to middle school), documenting relationship-based (i.e., teacher-child relationship, school friendships, peer acceptance and rejection, victimization) and context-based (e.g., school policies, classroom norms) factors as they pertain to child externalizing and internalizing symptoms. After describing gene-environment interplay mechanisms and genetic research methods, we present empirical examples of gene-and-school environment interplay that contributes to variation in child maladjustment. We conclude with a discussion of implications for theory, practice, and future directions in genetically informed research on the association between social relations in school and child development.</p

The CODAT wins project : the current status and recent findings of collaborative project of development of anthropometrical measures in twins

The COllaborative project of Development of Anthropometrical measures in Twins (CODATwins) project is a large international collaborative effort to analyze individual-level phenotype data from twins in multiple cohorts from different environments. The main objective is to study factors that modify genetic and environmental variation of height, body mass index (BMI, kg/m2 ) and size at birth, and additionally to address other research questions such as long-term consequences of birth size. The project started in 2013 and is open to all twin projects in the world having height and weight measures on twins with information on zygosity. Thus far, 54 twin projects from 24 countries have provided individual-level data. The CODATwins database includes 489,981 twin individuals (228,635 complete twin pairs). Since many twin cohorts have collected longitudinal data, there is a total of 1,049,785 height and weight observations. For many cohorts, we also have information on birth weight and length, own smoking behavior and own or parental education. We found that the heritability estimates of height and BMI systematically changed from infancy to old age. Remarkably, only minor differences in the heritability estimates were found across cultural– geographic regions, measurement time and birth cohort for height and BMI. In addition to genetic epidemiological studies, we looked at associations of height and BMI with education, birth weight and smoking status. Within-family analyses examined differences within same-sex and opposite-sex dizygotic twins in birth size and later development. The CODATwins project demonstrates the feasibility and value of international collaboration to address gene-by-exposure interactions that require large sample sizes and address the effects of different exposures across time, geographical regions and socioeconomic status

Can sports mitigate the effects of depression and aggression on peer rejection?

This study examined whether sports participation moderates the longitudinal link of depressive and aggressive symptoms with increased peer rejection. The sample consisted of 291 adolescents (50.5% girls), assessed at ages 12 and 13 years. Depressive and aggressive symptoms as well as peer rejection were assessed through peer nominations, whereas participation in team and individual sports was assessed via adolescents' self-reports. Regression analyses revealed that boys – but not girls – who displayed high levels of depressive symptoms experienced an increase in peer rejection. However, participation in team sports mitigated the association between depressive symptoms and increased peer rejection in boys, whereas participation in individual sports exacerbated that same association. Although aggressive symptoms were also associated with an increase in peer rejection for boys and girls, sports participation did not moderate this link. These results support the usefulness especially of team sports as part of prevention activities for vulnerable youth

Prospective links between friendship and early physical aggression : preliminary evidence supporting the role of friendship quality through a dyadic intervention

Positive friendships have been related to decreasing levels of children’s physical aggression over time. While this evidence calls for interventions aimed at helping children build good-quality friendships, tests of causality through experimental manipulations are still needed. The goal of this study was to examine whether an intervention aimed to increase dyadic friendship quality could decrease children’s physical aggression at the peer-group level over a school year. A total of 34 aggressive children and each child’s best friend were randomly assigned to two groups: an experimental condition where the members in each dyad participated together in 12 weekly intervention sessions and a no-intervention control condition. Multiple sources were used to evaluate changes in friendship quality and children’s physical aggression. Results showed an indirect effect of the intervention on decreasing levels of physical aggression through the improvement of one specific feature of friendship quality: conflict resolution. These results point to the usefulness of including this relational aspect in intervention programs targeting aggressive children

Variety of gambling activities from adolescence to age 30 and association with gambling problems: a 15‐year longitudinal study of a general population sample

Participants A mixed‐gender general population cohort assessed at ages 15 (n = 1882), 22 (n = 1785) and 30 (n = 1358). Measurements Adolescent and adult versions of the South Oaks Gambling Screen (SOGS). Findings Group‐based trajectory analysis identified three distinct trajectories: a late‐onset low trajectory (26.7% of sample) initiating gambling at age 22, an early‐onset low trajectory (64.8% of sample), characterized by one to two different activities from age 15 onwards and a high trajectory (8.4% of sample), with an average of four to five different activities from age 15 to 30. Males (14.2%) were four times more likely to be on a high trajectory than females (3.5%) (P < 0.001). Preferred types of gambling activities were similar across the three trajectories. Participants on a high trajectory reported higher gambling frequency at ages 15 and 30, and were more likely to experience problem gambling at age 30: 3.09 [95% confidence interval (CI) = 1.66, 5.75] and 2.26 (95% CI = 1.27, 4.04) times more, respectively, than late‐onset low and early‐onset low participants, even when socio‐economic status (SES), frequency of gambling and problem gambling in adolescence, gender, age 30 education, SES and frequency of gambling were controlled. Conclusions Engaging in several different types of gambling in early adulthood appears to be a risk factor for emergence of problem gambling

Trajectories of gambling problems from mid-adolescence to age 30 in a general population cohort

Studies of gambling starting before adulthood in the general population are either cross-sectional, based on the stability of these behaviors between 2 time points, or cover a short developmental period. The present study aimed at investigating the developmental trajectories of gambling problems across 3 key periods of development, mid-adolescence, early adulthood, and age 30, in a mixed-gender cohort from the general population. Using a semiparametric mixture model, trajectories were computed based on self-reports collected at ages 15 (N = 1,882), 22 (N = 1,785), and 30 (N = 1,358). Two distinct trajectories were identified: 1 trajectory including males and females who were unlikely to have experienced gambling problems across the 15-year period, and 1 trajectory including participants likely to have experienced at least 1 problem over the last 12 months at each time of assessment. Participants following a high trajectory were predominantly male, participated frequently in 3 to 4 different gambling activities, and were more likely to report substance use and problems related to their alcohol and drug consumption at age 30. Thus, gambling problems in the general population are already observable at age 15 in a small group of individuals, who maintain some level of these problems through early adulthood, before moderately but significantly desisting by age 30, while also experiencing other addictive behaviors and related problem

Genetic and environmental influences on developmental trajectories of adolescent alcohol use

Adolescent alcohol use demonstrates distinct developmental trajectories with different times of onset, levels, and rates of growth. Twin research on adolescent alcohol use has shown that genetic influences are consistent with a gradual growth of risks, whereas non-shared environmental influences are more consistent with an accumulation of risks over time. The current study investigated the relative contributions of genetic and environmental influences on shaping different developmental trajectories of alcohol use through adolescence. Self-reported past year alcohol use was collected from 877 Canadian twins (47.1% males) at age 13, 14, 15, and 17-year-old. Growth mixture models were fit to examine different developmental trajectories of alcohol use, and biometric liability threshold models were fit to investigate genetic and environmental influences on the liability of belonging to identified trajectories. Three trajectories were identified: low (15.1%), early onset (8.2%), and normative increasing (76.7%). Memberships in the low and early onset group were under genetic (27.6% and 34.7%), shared (42.4% and 21.5%), and non-shared environment influences (30.0% and 43.8%). Membership in the normative increasing group was under genetic (37.7%) and non-shared environment influences (62.3%). Non-shared environmental influences were significantly larger for the normative increasing trajectory than for the low trajectory. These findings provide a more refined picture of genetic and environmental influences in the development of alcohol use in subgroups of adolescents. Genetic and environmental influences both matter, but to different degrees in different trajectories. Future research should identify specific shared and non-shared environmental experiences that distinguish different trajectories

Longitudinal links between gambling participation and academic performance in youth : a test of four models

Gambling participation and low academic performance are related during adolescence, but the causal mechanisms underlying this link are unclear. It is possible that gambling participation impairs academic performance. Alternatively, the link between gambling participation and low academic performance could be explained by common underlying risk factors such as impulsivity and socio-family adversity. It could also be explained by other current correlated problem behaviors such as substance use. The goal of the present study was to examine whether concurrent and longitudinal links between gambling participation and low academic performance exist from age 14 to age 17 years, net of common antecedent factors and current substance use. A convenience sample of 766 adolescents (50.6% males) from a longitudinal twin sample participated in the study. Analyses revealed significant, albeit modest, concurrent links at both ages between gambling participation and academic performance. There was also a longitudinal link between gambling participation at age 14 and academic performance at age 17, which persisted after controlling for age 12 impulsivity and socio-family adversity as well as current substance use. Gambling participation predicts a decrease in academic performance during adolescence, net of concurrent and antecedent personal and familial risk factors