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Objective: Peer groups represent a critical developmental context in adolescence, and there are many well‐documented associations between personality and peer behavior at this age. However, the precise nature and direction of these associations are difficult to determine as youth both select into, and are influenced by, their peers. Method: We thus examined the phenotypic, genetic, and environmental links between antisocial and prosocial peer characteristics and several personality traits from middle childhood to late adolescence (ages 11, 14, and 17 years) in a longitudinal twin sample (N = 3762) using teacher ratings of personality and self‐reports of peer characteristics. Results: Less adaptive trait profiles (i.e., high negative emotionality, low conscientiousness, and low agreeableness) were associated with more antisocial and fewer prosocial peer characteristics across time. Associations between personality traits related to emotionality (negative emotionality and extraversion) and peer behavior were largely attributable to shared genetic influences, while associations between personality traits related to behavioral control (conscientiousness and agreeableness) and peer behavior were due to overlapping genetic and shared environmental influences. Conclusions: Overall, results suggest a set of environmental presses that push youth toward both behavioral undercontrol and antisocial peer affiliations, making the identification of such influences and their relative importance a critical avenue of future work. [ABSTRACT FROM AUTHOR]

Background and Aims: Molecular genetic studies of alcohol and nicotine use have identified many genome‐wide association study (GWAS) loci. We measured associations between drinking and smoking polygenic scores (PGS) and trajectories of alcohol and nicotine use outcomes from late childhood to early adulthood, substance‐specific versus broader‐liability PGS effects, and if PGS performance varied for consumption versus problematic substance use. Design, setting, participants and measurements: We fitted latent growth curve models with structured residuals to scores on measures of alcohol and nicotine use and problems from ages 14 to 34 years. We then estimated associations between the intercept (initial status) and slope (rate of change) parameters and PGSs for drinks per week (DPW), problematic alcohol use (PAU), cigarettes per day (CPD) and ever being a regular smoker (SMK), controlling for sex and genetic principal components. All data were analyzed in the United States. PGSs were calculated for participants of the Minnesota Twin Family Study (n = 3225) using results from the largest GWAS of alcohol and nicotine consumption and problematic use to date. Findings Each PGS was associated with trajectories of use for their respective substances [i.e. DPW (βmean = 0.08; βrange = 0.02–0.12) and PAU (βmean = 0.12; βrange = −0.02 to 0.31) for alcohol; CPD (βmean = 0.08; βrange = 0.04–0.14) and SMK (βmean = 0.18; βrange = 0.05–0.36) for nicotine]. The PAU and SMK PGSs also exhibited cross‐substance associations (i.e. PAU for nicotine‐specific intercepts and SMK for alcohol intercepts and slope). All identified SMK PGS effects remained as significant predictors of nicotine and alcohol trajectories (βmean = 0.15; βrange = 0.02–0.33), even after adjusting for the respective effects of all other PGSs. Conclusions: Substance use‐related polygenic scores (PGSs) vary in the strength and generality versus specificity of their associations with substance use and problems over time. The regular smoking PGS appears to be a robust predictor of substance use trajectories and seems to measure both nicotine‐specific and non‐specific genetic liability for substance use, and potentially externalizing problems in general. [ABSTRACT FROM AUTHOR]

Educational success is associated with greater quality of life and depends, in part, on heritable cognitive and non-cognitive traits. We used polygenic scores (PGS) for smoking and educational attainment to examine different genetic influences on facets of academic adjustment in adolescence and educational attainment in adulthood. PGSs were calculated for participants of the Minnesota Twin Family Study (N = 3225) and included as predictors of grades, academic motivation, and discipline problems at ages 11, 14, and 17 years-old, cigarettes per day from ages 14 to 24 years old, and educational attainment in adulthood (mean age 29.4 years). Smoking and educational attainment PGSs had significant incremental associations with each academic variable and cigarettes per day. About half of the adjusted effects of the smoking and education PGSs on educational attainment in adulthood were mediated by the academic variables in adolescence. Cigarettes per day from ages 14 to 24 years old did not account for the effect of the smoking PGS on educational attainment, suggesting the smoking PGS indexes genetic influences related to general behavioral disinhibition. In sum, distinct genetic influences measured by the smoking and educational attainment PGSs contribute to academic adjustment in adolescence and educational attainment in adulthood. [ABSTRACT FROM AUTHOR]

Sexual development entails many experiences and is a major feature of adolescence. Most relevant behavioral genetic studies, however, focus primarily on sexual behaviors associated with health risks. We took a more normative, developmental perspective by examining genetic and environmental influences on five sexual behaviors ranging from dating to pregnancy in middle (Mage = 14.90 years) and late adolescence (Mage = 17.85 years) in a sample of twins (N = 3,762). Overall, behaviors that are more common and socially sanctioned (e.g., dating) were more heritable than behaviors that are less common and socially acceptable (e.g., sexual intercourse). That the etiology of different sexual behaviors is tied to their normativeness highlights the importance of considering the broader developmental context when studying sexual development. [ABSTRACT FROM AUTHOR]

Sexual debut, or first intercourse, predicts problem behaviors such as substance use. This association could reflect a direct effect of debut itself, general developmental trends, or the fact that some youth are more predisposed to a wide array of problem behaviors (e.g., risky sex, substance use). Understanding the association between sexual debut and substance use thus requires methods that can distinguish between these various accounts. In this study the association between sexual debut and substance use was investigated in a longitudinal sample of Mexican-origin youth (N = 674) assessed annually from 5th (Mage = 10.86 years, SD = 0.51) through 12th grade (Mage = 17.69 years, SD = 0.48). The longitudinal aspect of the data allowed the direct effect of sexual debut on substance use to be tested while accounting for long-term trends in substance use, and stable individual differences in those trends based on early risk and debut timing. Substance use increased over time, and early risk and debut were consistently associated with more substance use. Sexual debut also modestly predicted an increase in substance use after accounting for these effects, however. Taken together, results provide some evidence consistent with each of the potential explanations for the association between sexual debut and substance use across adolescence. [ABSTRACT FROM AUTHOR]

Background Recent work has demonstrated the codevelopment of personality traits and alcohol use characteristics from early adolescence to young adulthood. Few studies, however, have tested whether alcohol use initiation impacts trajectories of personality over this time period. We examined the effect of alcohol use initiation on personality development from early adolescence to young adulthood. Methods Participants were male ( nmen = 2,350) and female ( nwomen = 2,618) twins and adoptees from 3 community-based longitudinal studies conducted at the Minnesota Center for Twin and Family Research. Data on personality traits of Positive Emotionality ( PEM; Well-being), Negative Emotionality ( NEM; Stress Reaction, Alienation, and Aggression), and Constraint ( CON; Control and Harm Avoidance)-assessed via the Multidimensional Personality Questionnaire ( MPQ)-and age of first drink were collected for up to 4 waves spanning ages 10 to 32. Results Alcohol use initiation was associated with significant decreases in levels of Well-being and CON traits, most notably Control; and significant increases in levels of all NEM traits, particularly Aggression. In general, the effects of alcohol use initiation on personality traits were moderated by gender and enhanced among those with earlier age of first drink. Conclusions From early adolescence to young adulthood, alcohol use initiation predicts deviations from normative patterns of personality maturation. Such findings offer a potential mechanism underlying the codevelopment of personality traits and alcohol use characteristics during this formative period of development. [ABSTRACT FROM AUTHOR]

ABSTRACT Aims To examine the reciprocal effects between the onset and course of alcohol use disorder (AUD) and normative changes in personality traits of behavioral disinhibition and negative emotionality during the transition between adolescence and young adulthood. Design Longitudinal-epidemiological study assessing AUD and personality at ages 17 and 24 years. Setting Participants were recruited from the community and took part in a day-long, in-person assessment. Participants Male ( n = 1161) and female ( n = 1022) twins participating in the Minnesota Twin Family Study. Measurements The effects of onset (adolescent versus young adult) and course (persistent versus desistent) of AUD on change in personality traits of behavioral disinhibition and negative emotionality from ages 17 to 24 years. Findings Onset and course of AUD moderated personality change from ages 17 to 24 years. Adolescent onset AUD was associated with greater decreases in behavioral disinhibition. Those with an adolescent onset and persistent course failed to exhibit normative declines in negative emotionality. Desistence was associated with a 'recovery' towards psychological maturity in young adulthood, while persistence was associated with continued personality dysfunction. Personality traits at age 11 predicted onset and course of AUD, indicating personality differences were not due to active substance abuse. Conclusions Personality differences present prior to initiation of alcohol use increase risk for alcohol use disorder, but the course of alcohol use disorder affects the rate of personality change during emerging adulthood. Examining the reciprocal effects of personality and alcohol use disorder within a developmental context is necessary to improve understanding for theory and intervention. [ABSTRACT FROM AUTHOR]