Creating a social world: a developmental twin study of peer-group deviance

A life span developmental investigation of marriage and problem-drinking reduction

While prior literature has largely focused on marriage effects during young adulthood, it is less clear whether these effects are as strong in middle adulthood. Thus, we investigated age differences in marriage effects on problem-drinking reduction. We employed parallel analyses with two independent samples (analytic-sample Ns of 577 and 441, respectively). Both are high-risk samples by design, with about 50% of participants having a parent with lifetime alcohol use disorder. Both samples have been assessed longitudinally from early young adulthood to the mid-to-late 30s. Separate parallel analyses with these two samples allowed evaluation of the reproducibility of results. Growth models of problem drinking tested marriage as a time-varying predictor and thereby assessed age differences in marriage effects. For both samples, results consistently showed marriage effects to be strongest in early young adulthood and to decrease somewhat monotonically thereafter with age, reaching very small (and nonsignificant) magnitudes by the 30s. Results may reflect that role transitions like marriage have more impact on problem drinking in earlier versus later adulthood, thereby highlighting the importance of life span developmental research for understanding problem-drinking desistance. Our findings can inform intervention strategies aimed at reducing problem drinking by jumpstarting or amplifying natural processes of adult role adaptation.

The Links Among Cumulative Ecological Risk and Smartphone Addiction, Sleep Quality in Chinese University Freshmen: A Two-Wave Study

Purpose

While previous research has highlighted the influence of family, school, and peer factors on smartphone addiction and sleep quality, the cumulative effects of these risk factors and their underlying causal relationships remain poorly understood. Therefore, based on the cumulative risk model and the bioecological model of human development, this study examined the longitudinal associations between cumulative ecological risk and smartphone addiction and sleep quality.

Methods

A survey was conducted among 653 Chinese university freshmen (mean age 18.56) at two distinct time points, with a 6-month interval. The initial assessment focused on family, school, and peer risk factors, while the subsequent assessment focused on smartphone addiction and sleep quality.

Results

Approximately 63.71% of university freshmen were found to be at risk of exposure. Compared to other risk-exposure groups, the group with no-risk exposure exhibited the lowest scores for smartphone addiction and sleep quality. The relationships between cumulative ecological risk and smartphone addiction and sleep quality displayed a linear pattern and a discernible "gradient effect". Smartphone addiction was identified as a fully mediating factor in the link between cumulative ecological risk and sleep quality, with a mediating effect value of 0.08 (representing 44.44% of the total effect).

Conclusion

University freshmen face various risks associated with their families, schools, and peers. The cumulative ecological risk can, directly and indirectly, impact sleep quality by influencing smartphone addiction. Given the observed "gradient effect" of cumulative ecological risk on smartphone addiction and sleep quality, it is imperative to adopt comprehensive risk prevention strategies to mitigate the impact of each risk factor.

Deviant peer affiliation mediates the prospective association from impulsivity to alcohol use in late adolescence

INTRODUCTION

Previous research has found that impulsivity and deviant peer affiliation predict alcohol use among adolescents. However, it remains unclear to what extent these risk factors predict alcohol use in conjunction with one another, and to what extent they predict over and above correlated risk factors, such as pre-existing externalizing problems and sociodemographic characteristics. The present study tested the hypothesis that deviant peer affiliation would mediate the prospective association between impulsivity and alcohol use in adolescence (ages 13-18 years), controlling for a wide range of family and child-level covariates.

METHODS

Analyses were conducted using data from 2318 participants from the Longitudinal Cohort Study of the Project on Human Development in Chicago Neighborhoods. Participants were approximately 9, 12, or 15 years of age at wave 1 of the study, with waves 2 and 3 taking place at approximately 2-year intervals. The sample composition was 50.3% male, 46.1% Hispanic, 35.6% Black, non-Hispanic, 14.4% White, non-Hispanic, and 3.9% other race/ethnicity.

RESULTS

Results from path analyses indicated that the prospective association between impulsivity and alcohol use was mediated by peer deviance, but only for the oldest (age 15) cohort.

CONCLUSIONS

Findings from the present study suggest that despite impulsivity being a dispositional characteristic, its effects on alcohol use in later adolescence are achieved through a social pathway, via affiliation with deviant peers. It further suggests that this pathway, especially the link from impulsivity to affiliation with deviant peers, may not operate until late adolescence. Findings suggest that alcohol use may be prevented or reduced among impulsive adolescents by reducing their exposure to delinquent peers.

A systematic review of gene-by-intervention studies of alcohol and other substance use

Alcohol and other substance use problems are common, and the efficacy of current prevention and intervention programs is limited. Genetics may contribute to differential effectiveness of psychosocial prevention and intervention programs. This paper reviews gene-by-intervention (G×I) studies of alcohol and other substance use, and implications for integrating genetics into prevention science. Systematic review yielded 17 studies for inclusion. Most studies focused on youth substance prevention, alcohol was the most common outcome, and measures of genotype were heterogeneous. All studies reported at least one significant G×I interaction. We discuss these findings in the context of the history and current state of genetics, and provide recommendations for future G×I research. These include the integration of genome-wide polygenic scores into prevention studies, broad outcome measurement, recruitment of underrepresented populations, testing mediators of G×I effects, and addressing ethical implications. Integrating genetic research into prevention science, and training researchers to work fluidly across these fields, will enhance our ability to determine the best intervention for each individual across development. With growing public interest in obtaining personalized genetic information, we anticipate that the integration of genetics and prevention science will become increasingly important as we move into the era of precision medicine.

Common Liabilities in Internalizing Symptoms and Cigarette Use in Adolescence

INTRODUCTION

Substance use and mood disorders account for about 10% of the global burden of disease and, among adolescents, are a significant source of disability. The present study examined whether additive genetic or shared environmental factors influenced the covariance of internalizing symptoms and cigarette use during adolescence when both of these problems begin to increase.

AIMS AND METHODS

We used data (n = 1230 pairs of twins) from the Virginia Twin Study of Adolescent Behavioral Development (mean age = 15.3) to decompose the variance of internalizing symptoms, cigarette initiation, and quantity of cigarettes smoked in a variance decomposition model that included a beta coefficient to allow for estimates of cigarette initiation to influence quantity of cigarettes smoked.

RESULTS

In biometric models we were able to equate all parameter estimates by sex. After identifying the best fitting model, parameter estimates were calculated and the significance of overlapping paths between internalizing symptoms and cigarette initiation were tested. After accounting for the genetic architecture of cigarette initiation and quantity smoked, the covariance between internalizing symptoms and cigarette use was accounted for by sex-specific shared and unique environmental factors.

CONCLUSIONS

Among adolescents, the overlap in risk factors between internalizing symptoms and cigarette use is because of non-genetic, environmental factors. Further exploration of the environmental sources of variance involved in the onset of adolescents internalizing symptoms and cigarette use is warranted.

IMPLICATIONS

We find that during adolescence common environmental factors influence the association between internalizing symptoms and cigarette use. Correlated vulnerabilities because of environmental sources between internalizing and cigarette use may be open to intervention and likely will influence the progression of internalizing and cigarette use.

Twins and Causal Inference: Leveraging Nature's Experiment

In this review, we discuss how samples comprising monozygotic and dizygotic twin pairs can be used for the purpose of strengthening causal inference by controlling for shared influences on exposure and outcome. We begin by briefly introducing how twin data can be used to inform the biometric decomposition of population variance into genetic, shared environmental, and nonshared environmental influences. We then discuss how extensions to this model can be used to explore whether associations between exposure and outcome survive correction for shared etiology (common causes). We review several analytical approaches that can be applied to twin data for this purpose. These include multivariate structural equation models, cotwin control methods, direction of causation models (cross-sectional and longitudinal), and extended family designs used to assess intergenerational associations. We conclude by highlighting some of the limitations and considerations that researchers should be aware of when using twin data for the purposes of interrogating causal hypotheses.

Investigating the CYP2B6 rs3745274 and rs3211371 polymorphisms in Methadone-Responder and Non-Responder Addicts in Iran

Background

Methadone therapy is a major protocol in opioid addiction cases in many health care systems. Population-based studies have shown that in addicted people, the genetic profile affects their response to methadone therapy. Therefore, this study designed to examine the frequency of two SNPs of the CYP2B6 gene (rs3745274 and rs3211371) in addicted cases in two methadone-responders and methadone non-responders groups.

Methods

A total of 199 opioid-addicted individuals and 117 unaffected control subjects were genotyped for rs3745274 and rs3211371 polymorphisms of the CYP2B6 gene using the tetra-primer amplification refractory mutation system-polymerase chain reaction.

Results

Results of this study revealed the significant association of rs3745274 GG (p < 0.001; OR = 0.027; 95% CI = 0.14-0.49) and GT (p < 0.001; OR = 4.04; 95% CI = 2.26-7.21) genotypes with the risk of addiction in methadone-responders. Also, a significant association between rs3745274 GG (p < 0.001; OR = 0.28; 95% CI = 0.15-0.51) and GT (p < 0.001; OR = 5.1; 95% CI = 2.8-5.28) genotypes and addiction relapse was found in methadone non-responders.

Conclusion

Based on our findings, we can conclude that rs3745274 variant of CYP2B6 gene could serve as a potential biomarker, to evaluate the prognosis of addicted people fate under treatment with methadone.

Does application of complexity theory simplify concepts of psychiatry: Analogies and insights

Scientific curiosity has not been able to explain the cause of psychiatric illness based on primarily biological or social paradigm. Available literatures were explored to understand causality of psychiatric illness from perspective of physics. Theory of complexity and other relevant theories were extrapolated to address these questions. Mental illness appeared to be a complex interplay of reductionism and emergentism, genetic and epigenetics, stress and the vulnerability or the core and the periphery. Mental illness displayed complex interaction between biological trait and environmental state.

Genetic and environmental pathways to suicidal behavior: Reflections of a genetic epidemiologist

This paper presents a tentative typology of genetic and environmental pathways to suicidal behavior. Ten pathways are proposed and briefly illustrated: (i) direct effects from psychiatric disorders; (ii) direct effects from personality; (iii) direct effects of early adversity; (iv) direct effects of current adversity; (v) indirect effects of genes on selection into adversity (gene–environment correlation); (vi) interactions between genetic risk and current adversity: gene–environment interaction; (vii) interactions between early and current adversity: environment–environment interaction; (viii) interactions between culture and genes; (ix) dynamic developmental pathways involving causal loops from genes to environment and back again; and (x) gene × environment × development interaction.

Exposure to Community Violence, Affiliations With Risk-Taking Peer Groups, and Internet Gaming Disorder Among Chinese Adolescents: The Moderating Role of Parental Monitoring

Among adolescents, exposure to community violence (ECV) has been consistently linked to problem behaviors such as Internet gaming disorder (IGD). However, the associated risk and protective factors have not been adequately explored in past studies. Therefore, in accordance with the risk-buffering model and social development model, this study aimed to test whether parental monitoring moderated the relationship between ECV and IGD among adolescents, and whether this moderating effect was mediated by affiliations with risk-taking peer groups. A sample of 2,423 Chinese middle-school students anonymously responded to questionnaires that assessed ECV, IGD, affiliations with risk-taking peer groups, and parental monitoring. The results of structural equation modeling revealed that the interaction between ECV and parental monitoring negatively related to IGD among adolescents. Specifically, the positive relationship between ECV and IGD was stronger for adolescents, who reported low levels of parental monitoring than for those who reported high levels of parental monitoring. Moreover, this moderating effect was mediated by affiliations with risk-taking peer groups. These results suggest that parental monitoring is an important protective factor that can mitigate the risk of IGD among adolescents who have been exposed to community violence. Accordingly, these findings serve as an empirical base upon which prevention and intervention strategies that are aimed at mitigating the risk of IGD among adolescents can be developed.

The influence of parents and schools on developmental trajectories of antisocial behaviors in Caucasian and African American youths

African American youths are overrepresented in the American juvenile justice system relative to Caucasians. Yet, research on antisocial behaviors (ASB) has focused on predominantly Caucasian populations. Furthermore, relatively little is known about how environmental factors, such as supportive parenting (e.g., how close adolescents feel to their parent) and school connectedness (e.g., how supported adolescents feel at school), affect trajectories of ASB in Caucasians versus African Americans. This study mapped developmental trajectories of ASB in Caucasians (n = 10,764) and African Americans (n = 4,091) separately, using four waves of data from the National Longitudinal Study of Adolescent to Adult Health. We then examined supportive parenting and school connectedness on the trajectories of ASB. Four trajectories of ASB were identified for both Caucasians and African Americans: negligible, adolescence-peaked, low-persistence, and high-persistence ASB, although prevalence rates differed by racial-ethnic status. Supportive parenting reduced the risk of membership into the adolescence-peaked trajectory for both Caucasians and African Americans. However, school connectedness was less protective for African Americans than for Caucasians because it only predicted a lower risk of adolescence-peaked membership for African Americans. Findings may reflect the complex social dynamics between race and schools in the development of ASB.

The gene-environmental architecture of the development of adolescent substance use

BACKGROUND

Using a longitudinal twin design and a latent growth curve/autoregressive approach, this study examined the genetic-environmental architecture of substance use across adolescence.

METHODS

Self-reports of substance use (i.e. alcohol, marijuana) were collected at ages 13, 14, 15, and 17 years from 476 twin pairs (475 boys, 477 girls) living in the Province of Quebec, Canada. Substance use increased linearly across the adolescent years.

RESULTS

ACE modeling revealed that genetic, as well as shared and non-shared environmental factors explained the overall level of substance use and that these same factors also partly accounted for growth in substance use from age 13 to 17. Additional genetic factors predicted the growth in substance use. Finally, autoregressive effects revealed age-specific non-shared environmental influences and, to a lesser degree, age-specific genetic influences, which together accounted for the stability of substance use across adolescence.

CONCLUSIONS

The results support and expand the notion that genetic and environmental influences on substance use during adolescence are both developmentally stable and developmentally dynamic.

Childhood Risk Factors for Heavy Episodic Alcohol Use and Alcohol Problems in Late Adolescence: A Marginal Structural Model Analysis

OBJECTIVE

This study seeks to clarify the nature of the association between five well-studied late childhood predictors and alcohol-related behaviors in adolescence.

METHOD

We examined, in 7,168 subjects from the Avon Longitudinal Study of Parents and Children (ALSPAC), using linear probability and marginal structural models, the association between parental alcohol problems, peer group deviance, antisocial behavior, and low parental monitoring, and sensation seeking assessed at multiple times from ages 12.5 to 18 years and heavy episodic drinking and alcohol problems at ages 16.5, 17.5, and 20 years.

RESULTS

Based on the pattern of the attenuation in the association with heavy episodic drinking and alcohol problems from the linear probability to marginal structural models, our five factors were divisible into three groups. For parental alcohol problems, no substantial attenuation was seen. For peer group deviance and antisocial behavior, the associations in the marginal structural models were modestly attenuated (10%-20%). By contrast, for low parental monitoring and sensation seeking, moderate attenuations of 41% and 35%, respectively, were observed.

CONCLUSIONS

Our results are consistent with the hypothesis that all or nearly all of the association between parental alcohol problems and heavy episodic drinking and alcohol problems in mid to late adolescence is causal. For peer group deviance and antisocial behavior, the large majority of the associations appear to be causal, but confounding influences are also present. However, for low parental monitoring and sensation seeking, our findings suggest that a substantial proportion of the observed association with alcohol outcomes reflects confounding rather than causal influences.

"Maturing Out" of Binge and Problem Drinking

This article reviews literature aiming to explain the widespread reductions in binge and problem drinking that begin around the transition to young adulthood (i.e., "maturing out"). Whereas most existing literature on maturing out emphasizes contextual effects of transitions into adult roles and responsibilities, this article also reviews recent work demonstrating further effects of young adult personality maturation. As possible mechanisms of naturally occurring desistance, these processes could inform both public health and clinical interventions aimed at spurring similar types of drinking-related behavior change. This article also draws attention to evidence that the normative trend of age-related reductions in problem drinking extends well beyond young adulthood. Specific factors that may be particularly relevant to problem drinking desistance in these later periods are considered within a broader life span developmental framework.

Developmental Etiologies of Alcohol Use and Their Relations to Parent and Peer Influences Over Adolescence and Young Adulthood: A Genetically Informed Approach

BACKGROUND

Distinct changes in alcohol use etiologies occur during adolescence and young adulthood. Additionally, measured environments known to influence alcohol use such as peers and parenting practice can interact or be associated with this genetic influence. However, change in genetic and environmental influences over age, as well as how associations with measured environments change over age, is understudied.

METHODS

The National Longitudinal Study of Adolescent Health (Add Health) sibling subsample was used to examine data-driven biometric models of alcohol use over ages 13 to 27. Associations between friends' drinking, parental autonomy granting, and maternal closeness were also examined.

RESULTS

The best-fitting model included a 5-factor model consisting of early (ages 13 to 20) and overall (ages 13 to 27) additive genetic and unique environmental factors, as well as 1 overall common environment factor. The overall additive genetic factor and the early unique environment factor explained the preponderance of mean differences in the alcohol use over this portion of the life span. The most important factors explaining variance attributed to alcohol use changed over age. Additionally, friend use had the strongest associations with genetic and environmental factors at all ages, while parenting practices had almost no associations at any age.

CONCLUSIONS

These results supplement previous studies indicating changes in genetic and environmental influences in alcohol use over adolescence and adulthood. However, prior research suggesting that constraining exogenous predictors of genetic and environmental factors to have effects of the same magnitude across age overlooks the differential role of factors associated with alcohol use during adolescence. Consonant with previous research, friend use appears to have a more pervasive influence on alcohol use than parental influence during this age. Interventions and prevention programs geared toward reducing alcohol use in younger populations may benefit from focus on peer influence.

Assessing the interplay between multigenic and environmental influences on adolescent to adult pathways of antisocial behaviors

The current investigation utilized a developmental psychopathology approach to test the hypothesis that multigenic (i.e., dopaminergic and serotonergic genes) and multienvironmental factors interactively contribute to developmental pathways of antisocial behavior (ASB). A sample of 8,834 Caucasian individuals from the National Longitudinal Study of Adolescent to Adult Health (Add Health) were used to (a) examine the developmental pathways of ASB from age 13 to 32 using growth mixture modeling, (b) compute weighted multigenic risk scores (Add Health MRS) for ASB from six well-characterized polymorphisms in dopamine and serotonin genes, and (c) test the interaction between the Add Health MRS and a measures of support (incorporating indicators of both positive and negative support from parents and schools). Four pathways of adolescent to adult ASB emerged from the growth mixture models: low, adolescence-peaked, high decline, and persistent. Add Health MRS predicted the persistent ASB pathway, but not other ASB pathways. Males with high Add Health MRS, but not low MRS, had significantly greater odds of being in the adolescence-peaked pathway relative to the low pathway at low levels of school connectedness. Nonfamilial environmental influences during adolescence may have a cumulative impact on the development of ASB, particularly among males with greater underlying genetic risks.

Genetic and environmental sources of covariation between early drinking and adult functioning

The vast majority of individuals initiate alcohol consumption for the first time in adolescence. Given the widespread nature of its use and evidence that adolescents may be especially vulnerable to its effects, there is concern about the long-term detrimental impact of adolescent drinking on adult functioning. While some researchers have suggested that genetic processes may confound the relationship, the mechanisms linking drinking and later adjustment remain unclear. The current study utilized a genetically informed sample and biometric modeling to examine the nature of the familial influences on this association and identify the potential for genetic confounding. The sample was drawn from the Minnesota Twin Family Study (MTFS), a longitudinal study consisting of 2,764 twins assessed in 2 cohorts at regular follow-ups from age 17 to age 29 (older cohort) or age 11 to age 29 (younger cohort). A broad range of adult measures was included assessing substance use, antisocial behavior, personality, socioeconomic status, and social functioning. A bivariate Cholesky decomposition was used to examine the common genetic and environmental influences on adolescent drinking and each of the measures of adult adjustment. The results revealed that genetic factors and nonshared environmental influences were generally most important in explaining the relationship between adolescent drinking and later functioning. While the presence of nonshared environmental influences on the association are not inconsistent with a causal impact of adolescent drinking, the findings suggest that many of the adjustment issues associated with adolescent alcohol consumption are best understood as genetically influenced vulnerabilities. (PsycINFO Database Record

Molecular Genetic Influences on Normative and Problematic Alcohol Use in a Population-Based Sample of College Students

Background: Genetic factors impact alcohol use behaviors and these factors may become increasingly evident during emerging adulthood. Examination of the effects of individual variants as well as aggregate genetic variation can clarify mechanisms underlying risk.

Methods: We conducted genome-wide association studies (GWAS) in an ethnically diverse sample of college students for three quantitative outcomes including typical monthly alcohol consumption, alcohol problems, and maximum number of drinks in 24 h. Heritability based on common genetic variants (h²_SNP) was assessed. We also evaluated whether risk variants in aggregate were associated with alcohol use outcomes in an independent sample of young adults.

Results: Two genome-wide significant markers were observed: rs11201929 in GRID1 for maximum drinks in 24 h, with supportive evidence across all ancestry groups; and rs73317305 in SAMD12 (alcohol problems), tested only in the African ancestry group. The h²_SNP estimate was 0.19 (SE = 0.11) for consumption, and was non-significant for other outcomes. Genome-wide polygenic scores were significantly associated with alcohol outcomes in an independent sample.

Conclusions: These results robustly identify genetic risk for alcohol use outcomes at the variant level and in aggregate. We confirm prior evidence that genetic variation in GRID1 impacts alcohol use, and identify novel loci of interest for multiple alcohol outcomes in emerging adults. These findings indicate that genetic variation influencing normative and problematic alcohol use is, to some extent, convergent across ancestry groups. Studying college populations represents a promising avenue by which to obtain large, diverse samples for gene identification.

The Interplay of MAOA and Peer Influences in Predicting Adult Criminal Behavior

Evidence concerning the ability of genetic risk factors to moderate the effects of environments has continued to accumulate over the last decade or so. For the behavioral sciences, this means that genetic risk factors might interact with environmental triggers to influence various human outcomes, including antisocial and aggressive behaviors. The current study seeks to further expand this line of inquiry by examining data drawn from the National Youth Survey Family Study. More specifically, we examined whether a polymorphism in the promoter region of the MAOA gene might condition the influence of exposure to deviant peer groups in the prediction of criminogenic behavior. Our findings offer some mixed evidence that genotype might condition the influence of delinquent peer affiliation on antisocial behavior during the course of human development.

Genetic influences on adolescent behavior

Adolescence is a transitional, developmental phase with marked shifts in behavior, particularly as related to risk-taking and experimentation. Genetic influences on adolescent behavior also show marked changes across this developmental period; in fact, adolescence showcases the dynamic nature of genetic influences on human behavior. Using the twin studies literature on alcohol use and misuse, we highlight several principles of genetic influence on adolescent behavior. We illustrate how genetic influences change (increase) across adolescence, as individuals have more freedom to express their predispositions and to shape their social worlds. We show how there are multiple genetic pathways to risk, and how the environment can moderate the importance of genetic predispositions. Finally, we review the literature aimed at identifying specific genes involved in adolescent behavior and understanding how identified genes impact adolescent outcomes. Ultimately, understanding how genetic predispositions combine with environmental influences to impact pathways of risk and resilience should be translated into improved prevention and intervention efforts; this remains a rich area for future research.

Genetic and Environmental Factors Associated with Cannabis Involvement

Approximately 50-70% of the variation in cannabis use and use disorders can be attributed to heritable factors. For cannabis use, the remaining variance can be parsed in to familial and person-specific environmental factors while for use disorders, only the latter contribute. While numerous candidate gene studies have identified the role of common variation influencing liability to cannabis involvement, replication has been elusive. To date, no genomewide association study has been sufficiently powered to identify significant loci. Despite this, studies adopting polygenic techniques and integrating genetic variation with neural phenotypes and measures of environmental risk, such as childhood adversity, are providing promising new leads. It is likely that the small effect sizes associated with variants related to cannabis involvement will only be robustly identified in substantially larger samples. Results of such large-scale efforts will provide valuable single variant targets for translational research in neurogenetic, pharmacogenetic and non-human animal models as well as polygenic risk indices that can be used to explore a host of other genetic hypotheses related to cannabis use and misuse.

Antisocial peer affiliation and externalizing disorders in the transition from adolescence to young adulthood: Selection versus socialization effects

Prior research has demonstrated both socialization and selection effects for the relationship between antisocial peer affiliation and externalizing problems in adolescence. Less research has evaluated such effects postadolescence. In this study, a cross-lagged panel analysis was used to evaluate the extent of socialization (i.e., the effect of antisocial peer affiliation on subsequent externalizing disorders) and selection (i.e., the effect of externalizing disorders on subsequent antisocial peer affiliation) in the prospective relationships between antisocial peer affiliation and externalizing disorders from adolescence through young adulthood. Data from a community sample of 2,769 individuals (52% female) with assessments at ages 17, 20, 24, and 29 were used. Analyses with a latent externalizing measure (estimated using clinical symptom counts of nicotine dependence, alcohol use disorder, illicit drug use disorder, and adult antisocial behavior) and self-reported antisocial peer affiliation revealed significantly stronger socialization effects from age 17 to 20, followed by significantly stronger selection effects from age 20 to 24 and 24 to 29. To better understand the impact of college experience, moderation by college status was evaluated at each developmental transition. Results were generally consistent for those who were in or were not in college. Results suggest selection effects are more important in later developmental periods than earlier periods, particularly in relation to an overall liability toward externalizing disorders, likely due to more freedom in peer selection postadolescence. (PsycINFO Database Record

Antisocial peer affiliation and externalizing disorders: Evidence for Gene × Environment × Development interaction

Gene × Environment interaction contributes to externalizing disorders in childhood and adolescence, but little is known about whether such effects are long lasting or present in adulthood. We examined gene-environment interplay in the concurrent and prospective associations between antisocial peer affiliation and externalizing disorders (antisocial behavior and substance use disorders) at ages 17, 20, 24, and 29. The sample included 1,382 same-sex twin pairs participating in the Minnesota Twin Family Study. We detected a Gene × Environment interaction at age 17, such that additive genetic influences on antisocial behavior and substance use disorders were greater in the context of greater antisocial peer affiliation. This Gene × Environment interaction was not present for antisocial behavior symptoms after age 17, but it was for substance use disorder symptoms through age 29 (though effect sizes were largest at age 17). The results suggest adolescence is a critical period for the development of externalizing disorders wherein exposure to greater environmental adversity is associated with a greater expression of genetic risk. This form of Gene × Environment interaction may persist through young adulthood for substance use disorders, but it appears to be limited to adolescence for antisocial behavior.

Links between friends’ physical aggression and adolescents’ physical aggression

Exposure to deviant friends has been found to be a powerful source of influence on children’s and adolescents’ aggressive behavior. However, the contribution of deviant friends may have been overestimated because of a possible non-accounted gene-environment correlation (rGE). In this study, we used a cross-lagged design to test whether friends’ physical aggression at age 10 predicts an increase in participants’ physical aggression from age 10 to age 13 years. Participants were 201 pairs of monozygotic twins who are part of the Quebec Longitudinal Twin Study. We performed two sets of analyses. In the first set of analyses, using twins as singletons, we found that teacher-rated friends’ physical aggression predicted an increase in each twin’s self-reported physical aggression from age 10 to age 13, above and beyond auto-regressive and concurrent links. Second, we used within-pair differences in regard to friends’ physical aggression to predict an increase in within-pair differences in physical aggression, thus accounting for family-wide influences, including a likely rGE at age 10. No significant association was found, however. These results suggest that part of the influence attributed to friends in past studies may have been due to common underlying genetic effects on both physical aggression and association with physically aggressive friends.

Parent and peer influences on emerging adult substance use disorder: A genetically informed study

The present study utilizes longitudinal data from a high-risk community sample to examine the unique effects of genetic risk, parental knowledge about the daily activities of adolescents, and peer substance use on emerging adult substance use disorders (SUDs). These effects are examined over and above a polygenic risk score. In addition, this polygenic risk score is used to examine gene-environment correlation and interaction. The results show that during older adolescence, higher adolescent genetic risk for SUDs predicts less parental knowledge, but this relation is nonsignificant in younger adolescence. Parental knowledge (using mother report) mediates the effects of parental alcohol use disorder (AUD) and adolescent genetic risk on risk for SUD, and peer substance use mediates the effect of parent AUD on offspring SUD. Finally, there are significant gene-environment interactions such that, for those at the highest levels of genetic risk, less parental knowledge and more peer substance use confers greater risk for SUDs. However, for those at medium and low genetic risk, these effects are attenuated. These findings suggest that the evocative effects of adolescent genetic risk on parenting increase with age across adolescence. They also suggest that some of the most important environmental risk factors for SUDs exert effects that vary across level of genetic propensity.

Sibling Facilitation Mediates the Association Between Older and Younger Sibling Alcohol Use in Late Adolescence

Previous research has shown adolescent siblings are similar in their alcohol use and that this similarity is largely due to their shared environment. Using a genetically-informed sibling sample (196 full-biological pairs, 384 genetically unrelated pairs), we confirmed that the extent to which older siblings facilitate younger siblings' alcohol use (i.e., help them get alcohol) was one factor contributing to this shared environmental association. All analyses controlled for parent and peer influences. Findings were not moderated by sibling differences in genetic relatedness, gender, or ethnicity. Proximity in sibling age strengthened these associations, somewhat. Results were especially strong for sibling pairs where the older sibling was of legal drinking age. Implications for prevention and intervention are discussed.

The stability and predictors of peer group deviance in university students

BACKGROUND

Peer group deviance (PGD) is strongly associated with current and future externalizing behaviors. Debate remains about the degree to which this association arises from social selection. The first year of university constitutes a social experiment in which most individuals leave their home environment and recreate for themselves a new peer group.

METHODS

PGD was measured in newly arrived university students and then 6 and 18 months later. Other personality and family traits were also assessed.

RESULTS

PGD reported for high school friends at the start of university and university friends 6 months later were substantially correlated (+0.60). This correlation was only slightly diminished if restricted to students whose home was greater than 50 miles from the university. PGD was strongly predicted across three cohorts by male sex (+), extraversion (+), conscientiousness (-), a family history of alcohol use disorders (+) and depression (+), and religiosity (-).These predictors of PGD had a relatively stable impact over 18 months and, aside from sex, differed only modestly in males and females.

CONCLUSIONS

As individuals change social groups from high school to university, the level of PGD remains relatively stable, suggesting that individuals play a strong role in selecting peer groups with consistent characteristics. PGD is also predicted cross-sectionally and longitudinally by personality, family background and religiosity. Our results suggest that the association between personal and peer deviance is due at least in part to the effects of social selection.

Integrating Social-Contextual and Intrapersonal Mechanisms of "Maturing Out": Joint Influences of Familial-Role Transitions and Personality Maturation on Problem-Drinking Reductions

BACKGROUND

"Maturing out" of problem drinking is associated with both role transitions (e.g., getting married) and personality development. However, little is known concerning how these 2 mechanisms jointly influence problem-drinking desistance. This study investigated whether salutary effects of role transitions and personality occur at different points in young-adult development and whether they mediate one another's effects.

METHODS

Participants were initially recruited as first-year undergraduates, with family history of alcoholism overrepresented by design (N = 489). Using 4 waves of data at roughly ages 21, 25, 29, and 34, cross-lagged panel models estimated prospective relations among familial-role transitions (marriage or parenthood), personality (disinhibition, conscientiousness, and neuroticism), and problem drinking.

RESULTS

Mixed support was found for the prediction of roles being more strongly associated with earlier maturing out of problem drinking and personality being more strongly associated with later maturing out. Regarding mediation, no evidence was found for the expectation that role effects would be mediated by personality. However, results did support mediation of personality effects by role transitions. Specifically, lower disinhibition and higher conscientiousness in emerging adulthood predicted role adoption, which, in turn, predicted later problem-drinking reductions. Family history of alcoholism also distally influenced these mediation processes.

CONCLUSIONS

The differential timing of role and personality effects is consistent with the notion of decreasing contextual influences and increasing intrapersonal influences across development. In light of role incompatibility theory, results suggest that, over the course of development, the association of familial roles with problem drinking may increasingly reflect problem-drinking effects on role entry (i.e., role selection) and decreasingly reflect role entry effects on problem drinking (i.e., role socialization). As emerging-adult disinhibition and conscientiousness were associated with an apparent developmental cascade of both direct and indirect effects, findings highlight their potential importance as etiologic mechanisms and intervention targets.

School climate and delinquency among Chinese adolescents: analyses of effortful control as a moderator and deviant peer affiliation as a mediator

School climate is the quality and character of school life and reflects the norms, goals, values, interpersonal relationships, teaching and learning practices, and the organizational structure of a school. There is substantial literature documenting the negative association between positive school climate and adolescent delinquency, but little is known about the moderating and mediating mechanisms underlying this relationship. The aim of this study was to examine whether the direct and indirect pathways between school climate and adolescent delinquency would be moderated by effortful control. A sample of 2,758 Chinese adolescents (M age = 13.53 years, SD = 1.06) from 10 middle schools completed anonymous questionnaires regarding school climate, effortful control, deviant peer affiliation, and delinquency. After gender, age, geographical area, and socioeconomic status were included as covariates, the results revealed that school climate was significantly associated with adolescent delinquent behavior. This direct association was moderated by effortful control, such that the negative relationship between positive school climate and delinquency was only significant among adolescents low in effortful control. Moreover, the indirect association between school climate and delinquency via deviant peer affiliation was also moderated by effortful control. Specifically, the moderating effect of effortful control was not only manifested in the relationship between school climate and deviant peer affiliation, but also in the relationship between deviant peer affiliation and delinquency. These findings contribute to understanding the mechanisms through which positive school climate might reduce delinquent behavior and have important implications for prevention efforts aimed at diminishing adolescent delinquency.

A national Swedish longitudinal twin-sibling study of criminal convictions from adolescence through early adulthood

BACKGROUND

Prior twin and adoption studies have demonstrated the importance of both genetic and shared environmental factors in the etiology of criminal behavior (CB). However, despite substantial interest in life-course theories of CB, few genetically informative studies have examined CB in a developmental context.

METHOD

In 69,767 male-male twin pairs and full-sibling pairs with ≤ 2 years' difference in age, born 1958-1976 and ascertained from the Swedish Twin and Population Registries, we obtained information on all criminal convictions from 1973 to 2011 from the Swedish Crime Register. We fitted a Cholesky structural model, using the OpenMx package, to CB in these pairs over three age periods: 15-19, 20-24, and 25-29.

RESULTS

The Cholesky model had two main genetic factors. The first began at ages 15-19 and declined in importance over development. The second started at ages 20-24 and was stable over time. Only one major shared environmental factor was seen, beginning at ages 15-19. Heritability for CB declined from ages 15-29, as did shared environmental effects, although at a slower rate.

CONCLUSIONS

Genetic risk factors for CB in males are developmentally dynamic, demonstrating both innovation and attenuation. These results are consistent with theories of adolescent-limited and life-course persistent CB subtypes. Heritability for CB did not increase over time as might be predicted from active gene-environmental correlation. However, consistent with expectation, the proportion of variability explained by shared environmental effects declined slightly as individuals aged and moved away from their original homes and neighborhoods.

Exposure to peer deviance during childhood and risk for drug abuse: a Swedish national co-relative control study

BACKGROUND

Peer deviance (PD) is associated with risk for drug abuse (DA). Is this association causal?

METHOD

DA was recorded in official records. PD was defined as the percentage of peers residing in small communities with future DA registrations. We examined offspring in families whose community PD changed when the offspring was 0-15 years of age and then examined families where cousins or siblings differed in their years of exposure to low or high PD communities.

RESULTS

The duration of exposure to PD was strongly associated with future DA. Co-relative analyses for families whose exposure to PD declined suggested that the PD-DA association was largely non-causal. Within full-sibling pairs in such families, the length of exposure to low PD environments was unrelated to risk for DA. By contrast, co-relative analyses in families where exposure to PD increased over time indicated that the PD-DA association was largely causal. In such families, siblings who differed in the duration of their exposure to high PD differed in their risk for subsequent DA. These results were replicated in families whose PD changed because they moved or because of changes in the community in which they resided.

CONCLUSIONS

Within families whose social environment is improving over time, the association between PD exposure and offspring DA outcomes is not causal but is due to familial confounding. Within families whose social environment is deteriorating, the PD-DA association seems to be largely causal. Our measure of PD may also reflect broader aspects of the community environment beyond peers.

Multiple mechanisms influencing the relationship between alcohol consumption and peer alcohol use

BACKGROUND

Alcohol consumption is typically correlated with the alcohol use behaviors of one's peers. Previous research has suggested that this positive relationship could be due to social selection, social influence, or a combination of both processes. However, few studies have considered the role of shared genetic and environmental influences in conjunction with causal processes.

METHODS

This study uses data from a sample of male twins (N = 1,790) who provided retrospective reports of their own alcohol consumption and their peers' alcohol-related behaviors, from adolescence into young adulthood (ages 12 to 25). Structural equation modeling was employed to compare 3 plausible models of genetic and environmental influences on the relationship between phenotypes over time.

RESULTS

Model fitting indicated that one's own alcohol consumption and the alcohol use of one's peers are related through both genetic and shared environmental factors and through unique environmental causal influences. The relative magnitude of these factors, and their contribution to covariation, changed over time, with genetic factors becoming more meaningful later in development.

CONCLUSIONS

Peers' alcohol use behaviors and one's own alcohol consumption are related through a complex combination of genetic and environmental factors that act via correlated factors and the complementary causal mechanisms of social selection and influence. Understanding these processes can inform risk assessment as well as improve our ability to model the development of alcohol use.

Who gains? Genetic and neurophysiological correlates of BMI gain upon college entry in women

The present investigation examined P3 event-related electroencephalographic potentials and a short and selected list of addiction-related candidate gene single nucleotide polymorphisms (SNPs) within 84 female students, aged 18-20 yrs. The students were assigned to groups defined by the presence versus absence of a positive body mass index (BMI) change from the pre-college physical exam to the current day. Analyses revealed significantly greater P3 latencies and reduced P3 amplitudes during a response inhibition task among students who exhibited a BMI gain. BMI gain was also significantly associated with a ANKK1 SNP previously implicated in substance dependence risk. In logistic regression analyses, P3 latencies at the frontal electrode and this ANKK1 genotype correctly classified 71.1% of the students into the BMI groups. The present findings suggest that heritable indicators of impaired response inhibition can differentiate students who may be on a path toward an overweight or obese body mass.

Early age of alcohol initiation is not the cause of alcohol use disorders in adulthood, but is a major indicator of genetic risk. A population-based twin study

BACKGROUND AND AIMS

An early age of alcohol initiation (AAI) is associated with and has been hypothesized to be a cause of alcohol use disorders (AUD) in adulthood. Results from twin studies, however, indicate that AAI is an indicator of risk for AUD. We aimed to test a causal hypothesis versus a risk indicator hypothesis for the relationship between early AAI and AUD.

DESIGN

A population-based twin study using biometric twin modelling.

SETTING

Norway.

PARTICIPANTS

A population-based sample of 1336 Norwegian twins.

MEASUREMENTS

Life-time DSM-IV AUDs were assessed by structured clinical interview and AAI by questionnaire.

FINDINGS

The risk indicator model in which the association between AAI and AUD was explained by common vulnerability was the best fitted to the data. The heritability was 37% [95% confidence interval (CI) = 21%, 53%] for AAI and 62% (95% CI = 51%, 73%) for AUD. Genetic risk for AAI accounted for 44% (95% CI = 17%, 71%) of the total genetic risk for AUD and the correlation between genetic factors for AAI and AUD was -0.66 (95%CI -0.87, -0.46). Individual-specific environmental risk for AAI explained only 1% (95% CI = 0%, 3%) of the risk for AUD. Shared environmental factors did not influence AUD, but accounted for 25% (95% CI = 7%, 35%) of the variance in AAI.

CONCLUSIONS

The association between early age of alcohol initiation and alcohol use disorders in later life does not reflect a causal relationship, but is due almost entirely to common genetic risk factors.

Environmental risk, Oxytocin Receptor Gene (OXTR) methylation and youth callous-unemotional traits: a 13-year longitudinal study

Youth with high callous-unemotional traits (CU) are at risk for early-onset and persistent conduct problems. Research suggests that there may be different developmental pathways to CU (genetic/constitutional vs environmental), and that the absence or presence of co-occurring internalizing problems is a key marker. However, it is unclear whether such a distinction is valid. Intermediate phenotypes such as DNA methylation, an epigenetic modification regulating gene expression, may help to clarify etiological pathways. This is the first study to examine prospective inter-relationships between environmental risk (prenatal/postnatal) and DNA methylation (birth, age 7 and 9) in the prediction of CU (age 13), for youth low vs high in internalizing problems. We focused on DNA methylation in the vicinity of the oxytocin receptor (OXTR) gene as it has been previously implicated in CU. Participants were 84 youth with early-onset and persistent conduct problems drawn from the Avon Longitudinal Study of Parents and Children. For youth with low internalizing problems (46%), we found that (i) OXTR methylation at birth associated with higher CU (age 13) as well as decreased experience of victimization during childhood (evocative epigenetic-environment correlation; birth-age 7), (ii) higher prenatal parental risks (maternal psychopathology, criminal behaviors, substance use) associated with higher OXTR methylation at birth and (iii) OXTR methylation levels were more stable across time (birth-age 9). In contrast, for youth with high internalizing problems, CU were associated with prenatal risks of an interpersonal nature (that is, intimate partner violence, family conflict) but not OXTR methylation. Findings support the existence of distinct developmental pathways to CU.

Externalizing Disorders and Environmental Risk: Mechanisms of Gene-Environment Interplay and Strategies for Intervention

Though heritable, externalizing disorders have a number of robust associations with several environmental risk factors, including family, school, and peer contexts. To account for these associations, we integrate a behavioral genetic perspective with principles of a developmental cascade theory of antisocial behavior. The major environmental contexts associated with child externalizing problems are reviewed, as are the processes of gene-environment interplay underlying these associations. Throughout, we discuss implications for prevention and intervention. Three major approaches designed to reduce child externalizing behavior are reviewed. Prevention and intervention programs appear to be most successful when they target individuals or communities most at risk for developing externalizing disorders, rather than applied universally. We end by commenting on areas in need of additional research concerning environmental influences on persistent externalizing behaviors.

Genetic and environmental influences on affiliation with deviant peers during adolescence and early adulthood

Adolescence and early adulthood is a time when peer groups become increasingly influential in the lives of young people. Youths exposed to deviant peers risk susceptibility to externalizing behaviors and related psychopathology. In addition to environmental correlates of deviant peer affiliation, a growing body of evidence has suggested that affiliation with deviant peers is heritable. This study examined the magnitude of genetic and environmental influences on affiliation with deviant peers, changes in the relative importance of these factors, and which of these factors contribute to the stability of affiliation across this critical developmental period using a longitudinal twin study design that assessed same-sex twins (485 monozygotic pairs, 271 dizygotic pairs) at 3 discrete ages: 15, 18, and 21 years of age. Biometric models revealed that genetic influences increased with age. New genetic influences appeared during late adolescence, and no new genetic influences emerged by age 21. Environmental influences shared by sibling pairs decreased with age, while the proportion of nonshared environmental effects unique to each individual remained relatively stable over the course of development. Shared environmental influences were largely age-overlapping, whereas nonshared environmental influences were largely age-specific. In summary, this study found variance in affiliation with deviant peers is explained by shared and nonshared environment effects as well as by genetic influences (46% by age 21), supporting the role of genetically influenced selection factors. The shared environment was almost exclusively responsible for the stability in late adolescence, while genetic influences were primarily responsible for stability in early adulthood.

Overview of Behavioral Genetics Research for Family Researchers

This article provides an overview of the methods, assumptions, and key findings of behavioral genetics methodology for family researchers with a limited background. We discuss how family researchers can utilize and contribute to the behavioral genetics field, particularly in terms of conducting research that seeks to explain shared environmental effects. This can be done, in part, by theoretically controlling for genetic confounds in research that seeks to determine cause-and-effect relationships among family variables and individual outcomes. Gene-environment correlation and interaction are especially promising areas for the family researcher to address. Given the methodological advancements in the field, we also briefly comment on new methods in molecular genetics for studying psychological mental health disorders.

The road not taken: life experiences in monozygotic twin pairs discordant for major depression

In an effort to understand how environmental experiences contribute to risk for major depression (MD), we conducted joint autobiographical interviews with 14 pairs of monozygotic twins (mean age 51.2) rigorously discordant for a lifetime history of MD. Twelve of the pairs could be sorted into four broad categories. In two pairs, discordance was associated with a single traumatic event occurring to the affected twin. In seven pairs, the well twin had one stable, long-term, successful romantic relationship, whereas the affected co-twin had romantic reversals one or more of which precipitated depressive episodes. These pairs varied in the degree to which the romantic problems seemed to arise from bad luck or poor choices. In one pair, occupational difficulties were strongly related to discordance in experiences with MD. In two pairs, several mechanisms seemed to be at work. Discordance in the quality of intimate love relationships was the most common etiological factor revealed by interview in these discordant pairs, with single dramatic events and occupational problems being considerably rarer. Even in this best of natural experiments, the causal interrelationship between personality, environment and depressive episodes was not always clear. Many pairs illustrated the protective effects of planfulness and the malignant effect of cumulative continuity where early difficulties in relationships shaped the subsequent life course. These results speak both to the importance of environmental influences on human well-being and psychopathology, and the complexity of the causal paths underlying their effects.

Genetic influences on adolescent sexual behavior: Why genes matter for environmentally oriented researchers

There are dramatic individual differences among adolescents in how and when they become sexually active adults, and early sexual activity is frequently cited as a cause of concern for scientists, policymakers, and the general public. Understanding the causes and developmental impact of adolescent sexual activity can be furthered by considering genes as a source of individual differences. Quantitative behavioral genetics (i.e., twin and family studies) and candidate gene association studies now provide clear evidence for the genetic underpinnings of individual differences in adolescent sexual behavior and related phenotypes. Genetic influences on sexual behavior may operate through a variety of direct and indirect mechanisms, including pubertal development, testosterone levels, and dopaminergic systems. Genetic differences may be systematically associated with exposure to environments that are commonly treated as causes of sexual behavior (gene-environment correlation). Possible gene-environment correlations pose a serious challenge for interpreting the results of much behavioral research. Multivariate, genetically informed research on adolescent sexual behavior compares twins and family members as a form of quasi experiment: How do twins who differ in their sexual experiences differ in their later development? The small but growing body of genetically informed research has already challenged dominant assumptions regarding the etiology and sequelae of adolescent sexual behavior, with some studies indicating possible positive effects of teenage sexuality. Studies of Gene × Environment interaction may further elucidate the mechanisms by which genes and environments combine to shape the development of sexual behavior and its psychosocial consequences. Overall, the existence of heritable variation in adolescent sexual behavior has profound implications for environmentally oriented theory and research.

Decision making in the pathway from genes to psychiatric and substance use disorders

In influencing risk for psychiatric and substance use disorders, genes are typically conceptualized as working in silent physiological pathways in the bowels of our biology, far from the influences of human desires. I here argue that this model of gene action is too restricted. At the individual, family and societal level, humans can, through their decision-making capacity, intervene in causal pathways from genes to behavior. At the individual level, I present four paradigmatic cases involving alcohol dependence, major depression, general externalizing behaviors and animal phobia showing how human decisions can inhibit the expression of risk genes. I review the literatures demonstrating that parental behaviors can suppress or augment the heritability of traits in their children, and social attitudes can alter and even create causal pathways from genes to phenotypes. We evolved from organisms whose nervous systems were networks of reflexes that then developed simple cognitive systems and finally self-reflection. Just as our cognitions have gone 'meta,' we are now nearing a time when we can go 'meta' about our genetic risk. For many psychiatric disorders, our risk genes are not entirely cordoned off in our silent, purposeless biological substrate. Rather, we are able to make decisions that impact on the expression of our own genomes, those of our loved ones and those of our friends and neighbors. Our actions and our genes are often weaved together, integrated into the fabric of our lives.

Peer deviance, alcohol expectancies, and adolescent alcohol use: explaining shared and nonshared environmental effects using an adoptive sibling pair design

Previous research suggests adolescent alcohol use is largely influenced by environmental factors, yet little is known about the specific nature of this influence. We hypothesized that peer deviance and alcohol expectancies would be sources of environmental influence because both have been consistently and strongly correlated with adolescent alcohol use. The sample included 206 genetically related and 407 genetically unrelated sibling pairs assessed in mid-to-late adolescence. The heritability of adolescent alcohol use (e.g., frequency, quantity last 12 months) was minimal and not significantly different from zero. The associations among peer deviance, alcohol expectancies, and alcohol use were primarily due to shared environmental factors. Of special note, alcohol expectancies also significantly explained nonshared environmental influence on alcohol use. This study is one of few that have identified specific environmental variants of adolescent alcohol use while controlling for genetic influence.

Four factors for the initiation of substance use by young adulthood: a 10-year follow-up twin and sibling study of marital conflict, monitoring, siblings, and peers

This study examined genetic and environmental influences on associations among marital conflict about the child, parental monitoring, sibling relationship negativity, and peer delinquency during adolescence and initiation of illegal drug use by young adulthood. The sample comprised data collected longitudinally from same-sex sibling pairs and parents when the siblings were 10-18 years old (M = 14.5 and 12.9 years for Child 1 and Child 2, respectively) and 20-35 years old (M = 26.8 and 25.5 years for Child 1 and Child 2, respectively). Findings indicate four factors that explain the initiation of illegal drug use: two shaped by genetic influences and two shaped by environments shared by siblings. The two genetically shaped factors probably have distinct mechanisms: one a child-initiated coercive process in the family and the other parent and peer processes shaped by the child's disclosure. The environmentally influenced factors seem distinctively shaped by poor parental monitoring of both sibs and the effects of siblings on each other's deviancy.

Testing multiple levels of influence in the intergenerational transmission of alcohol disorders from a developmental perspective: the example of alcohol use promoting peers and μ-opioid receptor M1 variation

This study examined the interplay between the influence of peers who promote alcohol use and μ-opioid receptor M1 (OPRM1) genetic variation in the intergenerational transmission of alcohol use disorder (AUD) symptoms while separating the "traitlike" components of AUD symptoms from their age-specific manifestations at three ages from emerging adulthood (17-23 years) to adulthood (29-40 years). The results for males were consistent with genetically influenced peer selection mechanisms as mediators of parent alcoholism effects. Male children of alcoholics were less likely to be carriers of the G allele in single nucleotide polymorphism A118G (rs1799971), and those who were homozygous for the A allele were more likely to affiliate with alcohol use promoting peers who increased the risk for AUD symptoms at all ages. There was evidence for women of an interaction between OPRM1 variation and peer affiliations but only at the earliest age band. Peer influences had stronger effects among women who were G-carriers. These results illustrate the complex ways in which the interplay between influences at multiple levels of analysis can underlie the intergenerational transmission of alcohol disorders as well as the importance of considering age and gender differences in these pathways.