Rethinking Timing of First Sex and Delinquency

Sex Differences in the Etiology of Victimization in Adulthood

Until relatively recently, the study of victimization has been largely outside the purview of behavioral geneticists and evolutionary psychologists. Recent victimology research, however, has shown that genetic and evolutionary forces are connected to the risk of victimization. The current study expands on these findings by examining whether genetic influences differentially explain victimization in males and females. To do so, we use a sample of sibling pairs drawn from the National Longitudinal Study of Adolescent to Adult Health (Add Health; N = 4,244). The analyses revealed no significant quantitative sex differences in the etiology of adult victimization. However, the results of this study do highlight the importance of accounting for genetic factors when studying the etiology of specific types of adult victimization. We conclude by discussing the implications of the current study for future research.

Sexual Self-Concept After Child Maltreatment: The Role of Resilient Coping and Sexual Experience Among U.S. Young Adults

Evidence supports sexual experience as normative and health-promoting for many, but this picture is less clear for people with histories of adversity. Amazon Mechanical Turk (MTurk) was used to garner data from a sample of 362 young adults (aged 18-25) wherein 44.5% (n = 161) identified as women. We assessed longitudinal associations between child maltreatment and sexual self-concept, as mediated by sexual behaviors and sexual partners, and whether resilient coping moderated these associations using structural equation modeling. Although both child maltreatment and resilient coping were directly associated with aspects of sexual experience, only resilient coping was directly associated with sexual self-concept. In addition, we found support for sexual experience as a mediator between child maltreatment/resilient coping and sexual self-concept. Specifically, cumulative maltreatment was associated with more sexual partners, which was associated with higher sexual self-monitoring. Resilient coping was associated with more sexual partners and more sexual behaviors, which was associated with higher sexual self-monitoring and higher sexual self-consciousness, sexual assertiveness, sexual self-esteem, and sexual motivation, respectively. Thus, sexual behaviors and sexual partners operated independently. Findings contrast messaging that sexual experience is universally risky regardless of maltreatment history. Rather, sexual experience may foster positive sexual self-concept for some. Sexual health advocates must attend to differences between sexual behaviors and sexual partners in relation to sexual well-being, and support resilience in the sexual domain.

Examining the Longitudinal Connection Between Adolescent Delinquency and Risky Sexual Behaviors in a Sample of Males and Females

Adolescence is a time period that is highlighted by widespread involvement in delinquent behaviors. The long-term consequences associated with engaging in such behaviors is not entirely understood. There is some research showing, though, that adolescents who are involved in delinquency are at-risk for also engaging in an assortment of risky sexual behaviors. Whether this association is causal or the result of selection/confounding remains unclear. The current study sought to add to the literature on this topic by examining whether measures of adolescent delinquency predict later-life involvement in risky sexual behaviors (number of sexual partners, number of one-night stands, and being diagnosed with a sexually transmitted infection) in a sample from the United States. To do so, data drawn from the National Longitudinal Study of Adolescent to Adult Health (Add Health) were analyzed (N ranging from 5018 to 5964). The results revealed statistically significant associations between adolescent delinquency and risky sexual behaviors for males and females even after controlling for levels of self-control, exposure to peer substance use, parental socialization, and neighborhood disadvantage. These results suggest that the association between delinquent involvement and risky sexual behaviors is robust and future research should begin to systematically examine the developmental nature of this association.

Sexual and Physical Victimization and Health Correlates Among Norwegian Adolescents

Large-scale epidemiological studies have documented that many children and adolescents are exposed to different forms of victimization experiences. However, such population-based studies have rarely examined how specific types of victimization are correlated with health indicators. Thus, we investigated sexual victimization, physical victimization by parents, and physical victimization by peers and their associations with sexual health, mental health, and substance use. We gathered data from a nationally representative sample of Norwegian 18-19-year-old students in their final year of senior high school (N = 2075; 59.1% girls). The analyses showed that 12.1% of the adolescents reported sexual victimization experiences. Physical victimization was more prevalent: 19.5% of the respondents had been exposed to victimization from parents and 18.9% from peers. Multivariate analyses revealed specific associations between sexual victimization and a range of sexual health indicators, such as early sexual intercourse debut, many sexual partners, engaging in sex without contraception while intoxicated, and participating in sexual acts for payment. Neither physical victimization from parents nor from peers were correlated with these variables. However, all three forms of victimization were associated with impaired mental health and potential substance use problems. We conclude that a variety of victimization experiences should be addressed in policies for prevention of adolescent mental health and substance use problems. In addition, a special emphasis is warranted regarding sexual victimization: Sexual health policies should address such potential experiences in addition to more traditional themes such as reproductive health and should also include low-threshold services for young victims of sexual victimization.

Gene-environment interactions and the case of body mass index and obesity: How much do they matter?

We investigate the demographic and population health implications of gene-environment interactions (GxE) in the case of body mass index (BMI) and obesity. We seek to answer two questions: (a) what is the first-order impact of GxE effects on BMI and probability of obesity, e.g. the direct causal effect of G in different E's? and (b) how large is the impact of GxE effects on second-order health outcomes associated with BMI and obesity, such as type 2 diabetes (T2D) and disability? In contrast to most of the literature that focuses on estimating GxE effects, we study the implications of GxE effects for population health outcomes that are downstream of a causal chain that includes the target phenotype (in this case BMI) as the initial cause. To limit the scope of the paper, we focus on environments defined by birth cohorts. However, extensions to other environments (education, socioeconomic status (SES), early conditions, and physical settings) are straightforward.

Subjective Reactions to First Coitus in Relation to Participant Sex, Partner Age, and Context in a German Nationally Representative Sample of Adolescents and Young Adults

Analysis of a Finnish nationally representative student sample found that subjective reactions to first intercourse (mostly heterosexual; usually in adolescence) were highly positive for boys and mostly positive for girls, whether involved with peers or adults (Rind, 2022). The present study examined the generality of these findings by examining subjective reactions to first coitus (heterosexual intercourse) in a German nationally representative sample of young people (data collected in 2014). Most first coitus was postpubertal. Males reacted mostly positively and uncommonly negatively in similar fashion in all age pairings: boy-girl (71% positive, 13% negative); boy-woman (73% positive; 17% negative); man-woman (73% positive, 15% negative). Females' reactions were more mixed, similar in the girl-boy (48% positive; 37% negative) and woman-man (46% positive, 36% negative) groups, but less favorable in the girl-man group (32% positive, 47% negative). In logistic regressions, adjusting for other factors, rates of positive reactions were unrelated to age groups. These rates did increase, in order of importance, when participants were male, their partners were close, they expected the coitus to happen, and they affirmatively wanted it. Reaction rates were computed from the Finnish sample, restricting cases to first coitus occurring in the 2000s, and then compared to minors' reactions in the German sample. The Finns reacted more favorably, similarly in both minor-peer and minor-adult coitus, with twice the odds of reacting positively. It was argued that this discrepancy was due to cultural differences (e.g., Finnish culture is more sex-positive). To account for the reaction patterns shown in the adolescent-adult coitus, sizably at odds with expectations from mainstream professional thinking, an evolutionary framework was employed.

Reactions to Minor-Older and Minor-Peer Sex as a Function of Personal and Situational Variables in a Finnish Nationally Representative Student Sample

Felson et al. (2019) used a large-scale nationally representative Finnish sample of sixth and ninth graders to estimate the population prevalence of negative subjective reactions to sexual experiences between minors under age 18 and persons at least 5 years older and between minors and peer-aged partners for comparison. They then accounted for these reactions in multivariate analysis based on contextual factors. The present study argued that focusing exclusively on negative reactions short-changed a fuller scientific understanding. It analyzed the full range of reactions in the same sample, focusing on positive reactions. For reactions in retrospect, boys frequently reacted positively to minor-older sex (68%, n = 280 cases), on par with positive reactions to boy-peer sex (67%, n = 1510). Girls reacted positively to minor-older sex less often (36%, n = 1047) and to girl-peer sex half the time (48%, n = 1931). In both minor-older and minor-peer sex, rates of positive reactions were higher for boys vs. girls, adolescents vs. children, when partners were friends vs. strangers or relatives, with intercourse vs. lesser forms of sexual intimacy, with more frequent sex, and when not coerced. Boys reacted positively more often with female than male partners. In minor-older sex, partner age difference mattered for girls but not boys, and the minor's initiating the sex (14% for girls, 46% for boys) produced equally high rates of positive reactions. Most of these factors remained significant in multivariate analysis. The frequency of positive reactions, their responsiveness to context, the similarity in reaction patterns with minor-peer sex, and the generalizability of the sample were argued to contradict the trauma view often applied to minor-older sex, holding it to be intrinsically aversive irrespective of context.

A Longitudinal Investigation of Observed Adolescent Text-Based Sexting and Adjustment

Despite strong concerns that sexting poses risks for adolescents' well-being, previous research finds mixed results. Moreover, these studies rely heavily on self-report measures and cross-sectional designs. This study utilizes observational methods to examine longitudinal relations between text-based sexting and both negative and positive indicators of psychosocial adjustment. An ethnically diverse sample of 197 adolescents was provided smartphones that captured their text messages across high school, from 2008-2012. Two, two-day samples of text messages from grades 9-12 were content-coded (468,201 total observations). Sexting was defined as sending and receiving text-based statements about past, present, or hypothetical sexual behaviors occurring between dyadic texting partners. Each year, adolescents reported on negative (internalizing, externalizing, and social problems; borderline personality features) and positive (life satisfaction, group belongingness, and positive self-perceptions) indicators of their psychosocial adjustment. Using concurrent and longitudinal multilevel models, greater sexting at one time point than one's average (within-person) was only associated with lower levels of group belongingness within the same year. For girls only, text-based sexting more than others on average (between-person) was related to increased externalizing symptoms and borderline personality disorder features, as well as decreased life satisfaction, group belongingness, self-perceived social competence, and global self-worth. No within-person differences by gender emerged, nor did longitudinal associations. Future studies and intervention efforts should examine when and why higher sexting might be related to psychosocial problems among girls.

Factors associated with age of first sex among women screened for an observational contraceptive vaginal ring study in Kisumu, Kenya, 2014

Sex at an early age can have later life negative health outcomes. Insights on early sexual activity may help in the development of future health-promotion products and interventions related to pregnancy and sexually transmitted infections (STIs) prevention. Among Kenyan women participating in a contraceptive vaginal ring study, we determined: (1) the proportion with first sex at ≤15 years (early sex) and (2) factors associated with early sex. Baseline data collection and testing for pregnancy, STIs, and HIV were undertaken. A log-binomial or a modified Poisson regression was used to estimate univariable prevalence ratios and multivariable adjusted prevalence ratios (aPRs). Among 332 women aged 18-34 years, the median age of first sex was 16 years, with 40.1% experiencing early sex. Overall, 29.8% reported an older first sex partner (≥5 years); 83.9% indicated lack of readiness or intentions at first sex; and 56.2% received money, gifts, or favors as part of first sex. Early sex was more prevalent among inherited widows (a Luo cultural practice, aPR 1.49), gift recipients (aPR 1.38), women with a forced/unwanted sex history (aPR 1.42), or those with a partner of unknown or positive HIV status in the past 3 months (aPR 1.45). Sex before or at the age 15 may be associated with higher sexual risk behaviors. Complex power and gender relations may additionally influence exposure to sexual risk in our research setting.

Advancing the Psychometric Study of Human Life History Indicators : K Does Not Measure Life History Speed, but Theory and Evidence Suggest It Deserves Further Attention

In this article we attend to recent critiques of psychometric applications of life history (LH) theory to variance among humans and develop theory to advance the study of latent LH constructs. We then reanalyze data (n = 4,244) previously examined by Richardson et al. (Evolutionary Psychology, 15(1), 2017, https://doi.org/10.1177/1474704916666840 to determine whether (a) previously reported evidence of multidimensionality is robust to the modeling approach employed and (b) the structure of LH indicators is invariant by sex. Findings provide further evidence that a single LH dimension is implausible and that researchers should cease interpreting K-factor scores as empirical proxies for LH speed. In contrast to the original study, we detected a small inverse correlation between mating competition and Super-K that is consistent with a trade-off. Tests of measurement invariance across the sexes revealed evidence of metric invariance (i.e., equivalence of factor loadings), consistent with the theory that K is a proximate cause of its indicators; however, evidence of partial scalar invariance suggests use of scores likely introduces bias when the sexes are compared. We discuss limitations and identify approaches that researchers may use to further evaluate the validity of the K-factor and other applications of LH to human variation.

Developmental Trajectories of Adolescent Girls' Borderline Personality Symptoms and Sexual Risk Behaviors

Adolescence is a developmental period during which youth tend to initiate sexual behavior, which may include sexual risk behavior. Symptoms of borderline personality disorder (BPD) are associated with increased rates of risky behaviors. However, little is known about longitudinal associations between BPD symptoms and sexual risk behaviors during adolescence. This study examines developmental trajectories of adolescent girls' BPD symptoms and sexual risk behaviors in a community sample of Black and White girls from the Pittsburgh Girls Study (n = 1620). Dual trajectory modeling provided insights into the temporal precedence and co-development of BPD symptoms and sexual risk behaviors from ages 14 to 18. In order to examine the unique association between BPD symptoms and sexual risk behaviors, analyses controlled for symptoms of depression and conduct disorder, as well as race, sexual orientation, and pubertal development. Girls with more BPD symptoms at age 14 showed steeper growth over time in sexual risk behaviors from ages 14 to 18. Additionally, adolescents who showed steeper increases in BPD symptoms over time also showed steeper increases in sexual risk behaviors across adolescence. Notably, however, sexual risk behavior at age 14 was not significantly associated with longitudinal trajectories of BPD symptoms. Results suggest that adolescent girls with early symptoms of BPD are at heightened risk for the development of sexual risk behaviors during adolescence, while the reverse association does not hold. Implications for adolescent development and sexual risk behavior are discussed.

Sexual Development in Adolescence: An Examination of Genetic and Environmental Influences

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 (M_age  = 14.90 years) and late adolescence (M_age  = 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.

Sex, drugs, and early emerging risk: Examining the association between sexual debut and substance use across adolescence

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 5^th (M_age = 10.86 years, SD = 0.51) through 12^th grade (M_age = 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.

The Genetics of Externalizing Problems

Externalizing problems generally refer to a constellation of behaviors and/or disorders characterized by impulsive action and behavioral disinhibition. Phenotypes on the externalizing spectrum include psychiatric disorders, nonclinical behaviors, and personality characteristics (e.g. alcohol use disorders, other illicit substance use, antisocial behaviors, risky sex, sensation seeking, among others). Research using genetic designs including latent designs from twin and family data and more recent designs using genome-wide data reveal that these behaviors and problems are genetically influenced and largely share a common genetic etiology. Large-scale gene-identification efforts have started to identify robust associations between genetic variants and these phenotypes. However, there is still considerable work to be done. This chapter provides an overview of the current state of research into the genetics of behaviors and disorders on the externalizing spectrum.

SES-of-Origin and BMI in Youth: Comparing Germany and Minnesota

Increasing obesity is a world-wide health concern. Its most commonly used indicator, body mass index (BMI), consistently shows considerable genetic and shared environmental variance throughout life, the latter particularly in youth. Several adult studies have observed less total and genetically influenced variance with higher attained SES. These studies offer clues about sources of the 'obesity epidemic' but analogous youth studies of SES-of-origin are needed. Genetic and environmental influences and moderating effects of SES may vary in countries with different health policies, lifestyles, and degrees/sources of social inequality, offering further clues to the sources of the obesity epidemic. We examined SES-of-origin moderation of BMI variance in the German TwinLife study's cohorts assessed around ages 5, 11, 17, and 23-24, and in the Minnesota Twin Family Study's (MTFS) 11- and 17-year-old birth cohorts assessed longitudinally around ages 11, 17, and 23-24, comparing male and female twins and their parents. Age for age, both sexes' means and variances were greater in MTFS than in TwinLife. We observed that SES generally moderated genetic influences, more strongly in females, similar to most adult studies of attained-SES moderation of BMI. We interpreted differences in our SES-of-origin observations in light of inevitably-missing covariance between SES-of-origin and BMI in the models, mother-father and parent-offspring BMI correlations, and parental attained-SES-BMI correlations. We suggest that one source of the present obesity epidemic is social change that amplifies expression of genes both constraining SES attainment and facilitating weight gain.

Understanding Generational Differences in Early Fertility: Proximate and Social Determinants

Although US rates of early fertility have declined, they remain high relative to other high-income countries, and disparities by population group persist. The share of the US youth population with immigrant parents has expanded greatly, yet relatively little is known about generational variations in early fertility. This study used Add Health data to investigate: (1) differences by generational status in the risk of early childbearing; (2) to what extent observed differences reflected timing of sexual onset versus post-onset proximate determinants like contraceptive use; and (3) the influence of individual-, family-, and neighborhood-level social factors. Foreign-born and second-generation young women initiated both sexual activity and childbearing later than those with US-born parents. Sequential hazard models revealed the importance of later sexual onset in explaining delayed fertility among the foreign-born, and of family attributes for their later sexual onset. Post-onset behaviors were central to the delayed childbearing observed among the second generation.

Sexual intercourse, age of initiation and contraception among adolescents in Ireland: findings from the Health Behaviour in School-aged Children (HBSC) Ireland study

Background

The need to tackle sexual health problems and promote positive sexual health has been acknowledged in Irish health policy. Young people’s sexual behaviour however remains under-researched with limited national data available.

Methods

This study presents the first nationally representative and internationally comparable data on young people’s sexual health behaviours in Ireland. Self-complete questionnaire data were collected from 4494 schoolchildren aged 15–18 years as part of a broader examination of health behaviour and their context. The prevalence of sexual initiation, very early sexual initiation (< 14 years) and non-condom use at last intercourse are reported and used as outcomes in separate multilevel logistic regression models examining associations between sociodemographic characteristics, lifestyle characteristics and young people’s sexual behaviours.

Results

Overall, 25.7% of boys and 21.2% of girls were sexually initiated. Older age was consistently predictive of initiation for both boys and girls, as were alcohol, tobacco and cannabis involvement, living in poorer neighbourhoods and having good communication with friends. Involvement in music and drama was protective. Very early sexual initiation (< 14 years) was reported by 22.8% of sexually initiated boys and 13.4% of sexually initiated girls, and was consistently associated with rural living, cannabis involvement and bullying others for both. Boys’ very early initiation was predicted by alcohol involvement, receiving unhealthy food from parents and taking medication for psychological symptoms, whereas better communication with friends and more experience of negative health symptoms were protective. Girls’ very early initiation was predicted by being bullied and belonging to a non-Traveller community, whereas taking medication for physical symptoms and attending regular health checks was protective. Condom use was reported by 80% of sexually initiated students at last intercourse. Boys’ condom use was associated with older age, higher family affluence, bullying others, more frequent physical activity and health protective behaviours. For girls, condom use was predicted by belonging to a non-Traveller community, healthy food consumption, higher quality of life and being bullied, whereas taking medication for physical and psychological symptoms was associated with non-condom use.

Conclusions

These nationally representative research findings highlight the importance of focusing on young people as a distinct population subgroup with unique influences on their sexual health requiring targeted interventions and policy.

Electronic supplementary material

The online version of this article (10.1186/s12889-018-5217-z) contains supplementary material, which is available to authorized users.

Developmental pathways from maltreatment to risk behavior: Sexual behavior as a catalyst

Although delinquency, substance use, and sexual activity are established to be highly intercorrelated, the extant research provides minimal evidence in support of one particular sequence of risk behavior or on the cascade effects from maltreatment. The present study tested a longitudinal model incorporating maltreatment, deviant peers, sexual behavior, delinquency, and substance use to elucidate the sequential pathway(s) from maltreatment to each specific risk behavior throughout adolescence. Data came from a longitudinal study on the effects of maltreatment on adolescent development (N = 454) with four study assessments from early (Time 1 M age = 10.98) to late adolescence (Time 4 M age = 18.22). Results from the cross-lagged model showed a sequence from maltreatment to sexual behavior (Time 1), to delinquency (Time 2), to sexual behavior (Time 3), to substance use and delinquency (Time 4). These findings support sexual behavior as the initial risk behavior that is the catalyst for engagement in more advanced risk behaviors across adolescence.

Sexual Orientation and Involvement in Nonviolent and Violent Delinquent Behaviors: Findings From the National Longitudinal Study of Adolescent to Adult Health

This study examined the association between sexual orientation and nonviolent and violent delinquency across the life course. We analyzed self-reported nonviolent and violent delinquency in a sample of heterosexual males (N = 5220-7023) and females (N = 5984-7875), bisexuals (N = 34-73), gay males (N = 145-189), and lesbians (N = 115-150) from the National Longitudinal Study of Adolescent to Adult Health (Add Health). The analyses revealed, in general, that bisexuals were the most delinquent of the sexual orientation categories for both males and females. Additional analyses revealed that heterosexual males reported significantly higher levels of both violent and nonviolent delinquency than gay males, whereas lesbians reported more involvement in nonviolent delinquency and, to a lesser extent, violent delinquency relative to heterosexual females. Analyses also revealed that lesbians reported significantly more delinquent behavior, particularly for nonviolent delinquency, than gay males. Future research should explore the mechanisms that account for these observed patterns and how they can be used to more fully understand the etiology of delinquency.

Revisiting the Association Between Television Viewing in Adolescence and Contact With the Criminal Justice System in Adulthood

A substantial number of previous studies have reported significant associations between television viewing habits and a host of detrimental outcomes including increased contact with the criminal justice system. However, it remains unclear whether the results flowing from this literature are generalizable to other samples and whether previously observed associations are confounded due to uncontrolled genetic influences. The current study addresses these limitations using the National Longitudinal Study of Adolescent to Adult Health (Add Health). The results of the preliminary models, which do not include controls for genetic influences, produced a pattern of results similar to those previously reported in the extant literature. The results of the genetically informed models revealed that the associations between television viewing and antisocial outcomes are not causal, but rather are driven by uncontrolled genetic influences. Further replication is required, but these findings suggest that results drawn from the extant literature may not be trustworthy.

A Sex-Positive Framework for Research on Adolescent Sexuality

In this article, I propose a sex-positive framework for research on adolescent sexuality in which I consider consensual sexual activities in adolescence as developmentally normative and potentially healthy. The sex-positive framework is contrasted with the predominant "risk" perspective that presumes that abstinence from sexual activity is the ideal behavioral outcome for teenagers. Evidence from longitudinal and behavioral genetic studies indicates that engaging in sexual intercourse in adolescence does not typically cause worse psychological functioning. The relationship context of sexual experience may be a critical moderator of its psychological impact. Moreover, cross-cultural data on adolescents' contraception usage, unintended pregnancy, and sexually transmitted infections suggest that, despite the unacceptably high rate of negative health consequences among U.S. teenagers, adolescents can have the developmental capacity to regulate the health risks inherent in sexual activity. Understanding adolescent sexuality can be fostered by considering sexual well-being, a multidimensional construct that incorporates an adolescent's sexual self-efficacy, sexual self-esteem, feelings of sexual pleasure and satisfaction, and freedom from pain and negative affect regarding sexuality. New research is necessary to understand the development of adolescent sexual well-being, including its normative age trends, its reciprocal links with sexual behavior, and its impact on psychological and physical health.

Identifying the “truly disadvantaged”

There has been significant interest in examining the developmental factors that predispose individuals to chronic criminal offending. This body of research has identified some social-environmental risk factors as potentially important. At the same time, the research producing these results has generally failed to employ genetically sensitive research designs, thereby potentially generating biased parameter estimates. The current study addresses this gap in the literature by using both a standard social science methodology (SSSM) and two separate genetically informative research designs to examine whether parent, teacher, and peer risk factors are associated with four maladaptive outcomes: arrests, low IQ, reduced self-control, and a combined measure of the “truly disadvantaged.” Analysis of twin pairs drawn from the National Longitudinal Study of Adolescent to Adult Health revealed that the SSSMs produced upwardly biased estimates of the impact of social-environmental influences on each of the four outcomes. Once genetic factors were controlled, the effect of social-environmental risk was reduced (but remained significant in certain cases). We conclude by discussing these findings in the context of criminal justice policy and their implications for future criminological research.

Predictors of Sexual Activity in Haitian-American Adolescents

This study examined the impact of individual, peer, family, school, and neighborhood level variables on sexual activity among 276 Haitian-American adolescents. Differences between those who were sexually active and those who were not were analyzed using Chi square and t tests. Significant factors at p ≤ 0.1 were entered into logistic regression for the full group and for girls-only. Half of males and 36.6 % of females were sexually active. The multivariable model revealed that adolescents were more likely to be sexually active if they reported delinquent behaviors; had sexually active friends; and were living with only one parent, friends or relatives. For girls, living with both parents was protective against sexual activity, while substance use and emotional distress were risk factors. No language or acculturation measures were associated with sexual activity. Haitian-American adolescents may benefit from interventions that focus on gender-specific, contextual and cultural factors to prevent early sexual activity.

Proposing a Pedigree Risk Measurement Strategy: Capturing the Intergenerational Transmission of Antisocial Behavior in a Nationally Representative Sample of Adults

An impressive literature has revealed that variation in virtually every measurable phenotype is the result of a combination of genetic and environmental influences. Based on these findings, studies that fail to use genetically informed modeling strategies risk model misspecification and biased parameter estimates. Twin- and adoption-based research designs have frequently been used to overcome this limitation. Despite the many advantages of such approaches, many available datasets do not contain samples of twins, siblings or adoptees, making it impossible to utilize these modeling strategies. The current study proposes a measurement strategy for estimating the intergenerational transmission of antisocial behavior (ASB) within a nationally representative sample of singletons using an extended pedigree risk approach that relies on information from first- and second-degree relatives. An evaluation of this approach revealed a pattern of findings that directly aligned with studies examining ASB using more traditional twin- and adoption-based research designs. While the proposed pedigree risk approach is not capable of effectively isolating genetic and environmental influences, this overall alignment in results provides tentative evidence suggesting that the proposed pedigree risk measure effectively captures genetic influences. Future replication studies are necessary as this observation remains preliminary. Whenever possible, more traditional quantitative genetic methodologies should be favored, but the presented strategy remains a viable alternative for more limited samples.

Sexual risk at first coitus: Does alcohol make a difference?

This study examines whether use of alcohol at first coitus is associated with increased sexual risk for young women. First coitus is the focus of the investigation because it is a memorable, formative experience that has implications for subsequent sexual health. A community sample of young women ages 18-19 years (N = 227) completed retrospective interviews. Characteristics and perceptions of the first coital event were examined using chi squares and one-way multivariate analysis of variance (MANOVA) to determine if there were differences based on alcohol-involvement. Alcohol-involved first coitus events occurred in social settings with risky partners, were rated less positively, and were non-consensual relative to those that did not involve alcohol. Alcohol use was not related to condom use. Alcohol-involvement was associated with subsequent pairing of alcohol with sex and incapacitated rape. Adolescent alcohol use occurs in contexts that increases young women's sexual risk through exposure to risky partners.

Correlates of adolescent and young adult sexual initiation patterns

CONTEXT

Identifying adolescent characteristics associated with different patterns of sexual initiation is critical to promoting healthy sexual development.

METHODS

Patterns of sexual initiation were examined among 12,378 respondents to Waves 1 (1994-1995) and 4 (2008) of the National Longitudinal Study of Adolescent Health. Multinomial logistic regression explored associations between adolescent characteristics and membership in five latent classes capturing the timing, sequence, pace and variety of sexual initiation patterns.

RESULTS

Age and indicators of greater psychosocial conventionality were associated with membership in the atypical "postponers" class (characterized by postponement of oral, vaginal and anal sexual activity until early adulthood), although patterns of associations varied by gender. For example, compared with males who attended religious services at least once a week, males who never attended religious services were more likely to appear in the vaginal initiators/multiple behaviors class (characterized by initiation of vaginal sex first and then initiation of another behavior after at least one year), rather than in the postponers class (relative risk ratio, 2.5). Compared with women who prayed at least once a day, those who never prayed were more likely to be in the vaginal initiators/single behavior class (whose members typically engaged in only one type of behavior), rather than in the postponers class (2.0).

CONCLUSIONS

Individuals who are more adherent, and presumably more committed, to the attitudes, values and expectations of conventional society are more likely than others to delay multiple types of sexual activity until well beyond the norm for their peers.

The developmental progression of age 14 behavioral disinhibition, early age of sexual initiation, and subsequent sexual risk-taking behavior

BACKGROUND

Research has demonstrated a consistent relationship between early sexual experience and subsequent sexual risk-taking behaviors. We hypothesized that this relationship is due to a general predisposition toward behavioral disinhibition (BD), and that relationships among BD, early sex, and subsequent risky sexual behavior may be influenced by common genetic influences for males and common environmental influences for females.

METHODS

A prospective sample of 1,512 same-sex adolescent twins (50.2% female) was used. Adolescent BD was measured by clinical symptom counts of conduct disorder, oppositional defiant disorder, and self-reported delinquent behavior (age 14). Age of sexual initiation was defined as first age of consensual oral or penetrative sex (mean age ~17). Adult risky sexual behavior was defined by sexual behaviors under the influence of drugs and alcohol and number of casual sexual partners in the past year (age 24).

RESULTS

Multivariate analyses showed evidence for substantial common genetic variance among age 14 BD, age at sexual initiation, and adult risky sexual behavior for males, but not females. There was no significant difference in the degree of common environmental influence on these variables for females compared to males. Notably, age of sexual initiation was not significantly correlated with age 24 risky sexual behavior for females.

CONCLUSION

The relationship between early sex and later risky sex can be better understood through a general liability toward BD, which is influenced primarily by genetic factors for males. The association between age 14 BD and age of sexual initiation was influenced through a combination of genetic and environmental factors for females; however, age of sexual initiation does not appear to be a salient predictor of adult women’s sexual risk-taking behavior. Findings suggest that prevention programs aimed at reducing sexual risk behavior might target youth exhibiting BD by age 14, particularly males. More research is needed on what predicts adult sexual risk-taking behavior for females.

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.

Testing putative causal associations of risk factors for early intercourse in the study of twin adults: genes and environment (STAGE)

Adverse childhood experiences and substance use have been identified as potential causal risk factors for early-onset sexual intercourse. While it is possible that exposure to these risk factors directly increases the likelihood of engaging in early intercourse, an alternative explanation is that observed associations between these variables are due to shared familial confounds. These unmeasured confounds may increase the likelihood of being exposed to these risk factors and of engaging in early intercourse. Participants drawn from a population-based study of Swedish adult twins (ages 19-47 years; N = 12,126) reported on their history of exposure to early physical and sexual trauma, cigarette use, and cannabis use. We investigated the nature of the association between these risk factors and young age at first intercourse, using a comparison of twins differentially exposed to each risk factor. When compared to non-exposed, unrelated individuals, participants who reported adverse childhood experiences or who engaged in early cigarette use or cannabis use were more likely to engage in early intercourse. However, co-twin comparisons indicated that observed associations between these risk factors and early intercourse may be due to familial factors shared within twin pairs, and risk factor exposure may not lead directly to early intercourse. Our results suggest that preventing trauma exposure or preventing or delaying adolescents' cigarette smoking or cannabis use may not effectively delay intercourse onset; instead, other aspects of the adolescent's environment should be addressed.

True Love Waits? A Sibling-Comparison Study of Age at First Sexual Intercourse and Romantic Relationships in Young Adulthood

This study tested whether the timing of first sexual intercourse in adolescence predicts romantic outcomes in adulthood, including union formation, number of romantic partners, and relationship dissatisfaction. Participants were 1,659 same-sex sibling pairs from the National Longitudinal Study of Adolescent Health, who were followed from adolescence (mean age = 16 years) to young adulthood (mean age = 29 years). The timing of participants’ first sexual intercourse was classified as early (at age 14 or earlier), on time (between the ages of 15 and 19), or late (at age 19 or older). Compared with early and on-time age at first sex, late age at first sex was associated with decreased odds of marriage or nonmarital cohabitation and fewer romantic partners in adulthood. Among individuals who had married or cohabited with a partner, late timing of first sex was associated with significantly reduced levels of relationship dissatisfaction, even after controlling for genetic and environmental differences between families (using a sibling-comparison model), demographic outcomes in adulthood, and involvement in dating during adolescence. These results underscore the contribution of a life-span approach to our understanding of romantic relationships.

Why does early sexual intercourse predict subsequent maladjustment? Exploring potential familial confounds

OBJECTIVE

Previous studies have found an association between early age at first sexual intercourse and subsequent psychosocial maladjustment. Using a quasi-experimental approach, we examined the extent to which this observed association may be due to familial confounds not explored in prior research.

METHODS

Using a population-based cohort of Swedish adult twins (ages 19-47; N = 12,126), we examined the nature of the association between early sexual intercourse (i.e., first intercourse occurring before age 16) and various outcomes reflecting psychosocial health, including substance use, depression, criminal convictions, and adolescent childbearing. We used two methods--discordant-twin analyses and bivariate twin modeling--to estimate the extent to which genetic and environmental confounds explained observed associations.

RESULTS

Individuals who engaged in early intercourse were at greater risk for most of the adverse psychosocial health outcomes measured in this study. However, twin pairs discordant for engaging in early intercourse did not differ significantly in their risk for psychosocial maladjustment. Our results indicated that early age at first sexual intercourse and subsequent psychosocial maladjustment may be associated because of familial factors shared by twins.

CONCLUSIONS

Early intercourse may be associated with poor psychosocial health largely due to shared familial influences rather than through a direct causal connection. Therefore, effective and efficient interventions should address other risk factors common to early intercourse and poor psychosocial health.

Young women's adolescent experiences of oral sex: relation of age of initiation to sexual motivation, sexual coercion, and psychological functioning

Research examining oral sex during adolescence tends to investigate only potential negative consequences without considering its place in sexual development or distinctions between cunnilingus and fellatio. Using retrospective reports from 418 undergraduate women, we examined the relations among young women's ages of initiation of both cunnilingus and fellatio and sexual motives, experiences of sexual coercion, and indicators of psychological functioning. Age at cunnilingus initiation was unrelated to sexual coercion or psychological functioning; however it was related to engaging in sex for personal stimulation and gratification (personal drive motive) and to feel agentic, assertive, and skillful (power motive). Age at fellatio initiation was related to feelings of inferiority compared to others and a devaluing of the self (interpersonal sensitivity). Findings challenge the unilateral assumption that all adolescent sexual activity is negative and indicate the need for future research distinguishing between cunnilingus and fellatio.

Peer network drinking predicts increased alcohol use from adolescence to early adulthood after controlling for genetic and shared environmental selection

Research consistently links adolescents' and young adults' drinking with their peers' alcohol intake. In interpreting this correlation, 2 essential questions are often overlooked. First, which peers are more important, best friends or broader social networks? Second, do peers cause increased drinking, or do young people select friends whose drinking habits match their own? The present study combines social network analyses with family (twin and sibling) designs to answer these questions via data from the National Longitudinal Study of Adolescent Health. Analysis of peer nomination data from 134 schools (n = 82,629) and 1,846 twin and sibling pairs shows that peer network substance use predicts changes in drinking from adolescence into young adult life even after controlling for genetic and shared environmental selection, as well as best friend substance use. This effect was particularly strong for high-intensity friendships. Although the peer-adolescent drinking correlation is partially explained by selection, the present finding offers powerful evidence that peers also cause increased drinking.

Gene-environment interplay in the association between pubertal timing and delinquency in adolescent girls

Early pubertal timing places girls at elevated risk for a breadth of negative outcomes, including involvement in delinquent behavior. While previous developmental research has emphasized the unique social challenges faced by early maturing girls, this relation is complicated by genetic influences for both delinquent behavior and pubertal timing, which are seldom controlled for in existing research. The current study uses genetically informed data on 924 female-female twin and sibling pairs drawn from the National Longitudinal Study of Adolescent Health to (1) disentangle biological versus environmental mechanisms for the effects of early pubertal timing and (2) test for gene-environment interactions. Results indicate that early pubertal timing influences girls' delinquency through a complex interplay between biological risk and environmental experiences. Genes related to earlier age at menarche and higher perceived development significantly predict increased involvement in both nonviolent and violent delinquency. Moreover, after accounting for this genetic association between pubertal timing and delinquency, the impact of nonshared environmental influences on delinquency are significantly moderated by pubertal timing, such that the nonshared environment is most important among early maturing girls. This interaction effect is particularly evident for nonviolent delinquency. Overall, results suggest early maturing girls are vulnerable to an interaction between genetic and environmental risks for delinquent behavior.

Why don't smart teens have sex? A behavioral genetic approach

Academic achievement and cognitive ability have been shown to predict later age at first sexual intercourse. Using a sample of 536 same-sex twin pairs who were followed longitudinally from adolescence to early adulthood, this study tested whether relations between intelligence, academic achievement, and age at first sex were due to unmeasured genetic and environmental differences between families. Twins who differed in their intelligence or their academic achievement did not differ in their age at first sex. Rather, the association between intelligence and age at first sex could be attributed entirely to unmeasured environmental differences between families, whereas the association between academic achievement and age at first sex could be attributed entirely to genetic factors.

Body evaluation and coital onset: a population-based longitudinal study

This study examined the temporal relationship between body evaluation and coital onset. In a population-based longitudinal study, 1449 Norwegian girls and boys between 12 and 15 years of age were followed at 4 waves over a span of 13 years. Body evaluation was used in order to predict coital onset besides romantic appeal and psychological problems. For girls early in adolescence, body evaluation did not influence the probability of coital onset during the first 2-year period. In the subsequent 5-year period, body dissatisfaction increased the probability for coital onset when romantic appeal was held constant. Body evaluation did not influence the odds of coital onset among boys. The findings imply that the pattern of association between body evaluation and coital onset differs according to the timing of coital onset for girls. Future research needs to distinguish body image from romantic appeal in relation to first time sexual experiences.

Adolescent sexual activity and the development of delinquent behavior: the role of relationship context

Despite the well-established association between adolescent sexual activity and delinquent behavior, little research has examined the potential importance of relationship contexts in moderating this association. The current study used longitudinal, behavioral genetic data on 519 same-sex twin pairs (48.6% female) divided into two age cohorts (13-15 and 16-18 years olds) drawn from the National Longitudinal Study of Adolescent Health. Analyses tested whether adolescent sexual activity that occurred in romantic versus non-romantic relationships was associated with delinquency from adolescence to early adulthood, after controlling for genetic influences. Results indicated that, for both younger and older adolescents, common underlying genes influence both sexual behavior and delinquency. After controlling for these genetic influences, there was no within-twin pair association between sexual activity and delinquency in younger adolescents. In older adolescents, sexual activity that occurred in romantic relationships predicted lower levels of delinquency, both cross-sectionally and longitudinally, whereas sexual activity in non-romantic relationships predicted higher levels of delinquency. These results are consistent with emerging research that suggests that the psychological correlates of adolescent sexual activity may be moderated by the social context in which this activity occurs.

Suicide Attempts among Latinas who Experienced Early Sex Were Largely Mediated by Substance Abuse

The purpose of this study was to describe the role of substance abuse as a mediating factor between early sexual experiences and suicide attempts among adult Latinas. In our study participants (n=158), nearly 15% had attempted suicide and 39% experienced their first sexual encounter at an age of 15 or younger (referred to hereafter as "early sex"). Latinas who experienced early sex were more likely to attempt suicide [OR=2.4, p<0.05], and this relationship was largely mediated by substance abuse. An early sexual debut may indicate an environmental adversity on the child that calls for long term intervention for prevention of substance abuse as well as promotion of psychological well-being later in life.

Beyond Heritability: Twin Studies in Behavioral Research

The heritability of human behavioral traits is now well established, due in large measure to classical twin studies. We see little need for further studies of the heritability of individual traits in behavioral science, but the twin study is far from having outlived its usefulness. The existence of pervasive familial influences on behavior means that selection bias is always a concern in any study of the causal effects of environmental circumstances. Twin samples continue to provide new opportunities to identify causal effects with appropriate genetic and shared environmental controls. We discuss environmental studies of discordant twin pairs and twin studies of genetic and environmental transactions in this context.

Sexual Debut Timing and Depressive Symptoms in Emerging Adulthood

The association between sexual debut timing and depressive symptomatology in adolescence and emerging adulthood was examined using data from Waves I, II and III of the National Longitudinal Study of Adolescent Health. Respondents who reported never having sexual intercourse at Wave I and were 18-22 years of age at Wave III were included (n=5,061). Twenty percent of respondents experienced early (<age 16) and 49% experienced typical (ages 16-18) sexual debut. In bivariate analyses, pre-debut depressive symptoms were associated with earlier sexual debut among female but not male adolescents. In models adjusting for demographic characteristics and pre-debut depressive symptoms, sexual debut was positively related to adolescent (Wave II) depressive symptomatology, but only among female adolescents age less than sixteen. However, sexual debut timing was unassociated with emerging adult (Wave III) depressive symptomatology for both male and female respondents. Findings suggest sexual debut timing does not have implications for depressive symptomatology beyond adolescence.