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

Association between MTHFR c.677C>T variant and erectile dysfunction among males attending fertility clinic

Genetic risk factors have been shown to contribute to the development of sexual dysfunction. However, the role of methylenetetrahydrofolate reductase ( MTHFR ) gene variants in the risk of erectile dysfunction (ED) remains unclear. In this study, we recruited 1254 participants who underwent ED assessed by the International Index of Erectile Function-5. The MTHFR c.677C>T variant was also measured by fluorescence polymerase chain reaction (PCR). No significant difference in the genotypic frequency of the MTHFR C677T polymorphism (CC, CT, and TT) was observed between men from the ED and non-ED groups. In addition, on binary logistic regression analysis, both crude and adjusted models showed that the risk of ED was not significantly associated with the C677T polymorphism. Interestingly, a significantly higher frequency of the 677TT polymorphism was found in severe and moderate ED (P = 0.02). The positive correlation between the MTHFR 677TT polymorphism and severe ED was confirmed by logistic regression analysis, even after adjusting for potential confounders (odds ratio [OR] = 2.46, 95% confidence interval [CI] 1.15-5.50, P = 0.02). These findings suggest a positive correlation between the MTHFR 677TT polymorphism and the risk of severe ED. Identification of MTHFR gene polymorphisms may provide complementary information for ED patients during routine clinical diagnosis.

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.

Exploring Relationships Between Internalizing Problems and Risky Sexual Behavior: A Twin Study

Previous research links risky sexual behavior (RSB) to externalizing problems and to substance use, but little research has been conducted on relationships between internalizing problems (INT) and RSB. The current study addresses that literature gap, using both a twin sample from Colorado (N = 2567) and a second twin sample from Minnesota (N = 1131) in attempt to replicate initial results. We explored the hypothesis that the latent variable INT would be more strongly associated with the latent variable RSB for females than for males, examining relationships between INT and RSB via phenotypic confirmatory factor analysis and multivariate twin analyses. We found a small but significant phenotypic association between the latent variables. However, despite using two large twin samples, limited power restricted our ability to identify the genetic and environmental mechanisms underlying this association. Our sex differences hypothesis was not fully supported in either sample and requires further investigation. Our findings illustrate the complexity of the relationship between internalizing problems and risky sexual behavior.

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.

Adding up risks: Sexual debut and substance use among Italian university students

Adolescence and youth are periods of great changes in an individual's life, during which experiencing first events of the transition to adulthood and, sometimes, violating social norms. Literature has identified an association of risk behaviours with timing of first sexual intercourse, but scant information is available about their relationship with the use of protection or the choice of a casual partner. This study focuses on the relation between initiation of risk behaviours (get drunk and drug use) and initiation of intercourse. Using event history analysis - also in their competing risk form - on data on Italian university students collected in 2000-2001 and in 2017, we intend to verify to what extent the initiation and the timing to risk behaviours is associated with the circumstances of first intercourse (timing, use of protection, type of partner), and if and how initiation to risk behaviours interacts differently with age at sexual debut. Our results show that in a country such as Italy, where family and sexual norms are relatively traditional, young people who got drunk, used marijuana or ecstasy at least one time in their life are more likely to experience risky sexual intercourse.

Adolescent Sexual Behavior Patterns, Mental Health, and Early Life Adversities in a British Birth Cohort

This study tested adolescent sexual behavior patterns at age 14, their association with mental health at age 17 (psychological well-being, substance use, and self-harm attempts), and the influence of early life adversities upon this association. A British birth cohort (5,593 boys and 5,724 girls from the Millennium Cohort Study) was used. Latent class analysis suggested five subgroups of adolescent sexual behaviors: a "no sexual behavior" (50.74%), a "kisser" (39.92%), a "touching under clothes" (4.71%), a "genital touching" (2.64%), and an "all sexual activities" class (1.99%). Adolescents from the "kisser," "touching under clothes," "genital touching," and "all sexual activities" classes reported significantly more substance use and self-harm attempts compared to adolescents from the "no sexual behavior" group. The associations became weaker after controlling for early life adversities (reducing around 4.38% to 37.35% for boys, and 9.29% to 52.56% for girls), and reduced to a smaller degree after further controlling for mental health variables at 14. The associations between sexual behaviors and psychological well-being became non-significant after controlling for early life adversities. Adolescents who have engaged in low-intensity sexual activities at early age may have poorer reported mental health, a pattern that is stronger for girls and early life adversity may partially explain this association.

Etiological Overlap Between Sex Under the Influence and Number of Lifetime Sexual Partners

Drug and alcohol use is associated with risky sexual behavior (RSB). It is unclear whether this association is due to correlated liabilities (e.g., third variables influencing both traits), or whether use of drugs and alcohol during sexual decision making increases RSB. This study addresses this question by fitting a series of biometrical models using over 800 twin pairs assessed in early adulthood (m = 25.21 years). Measures included an index of sex under the influence (e.g., frequency that drugs or alcohol affect sexual decision making), number of lifetime sexual partners, and a general measure of substance use. Analyses suggest the covariance among these measures is explained by both genetic and environmental correlated liabilities. The overlap was not specific to sex under the influence, but was shared with a measure of general substance use. Models testing necessary but not sufficient parameters for direction of causation suggest that sex under the influence is unlikely to cause an increase in RSB; more evidence for reverse causation was found.

Adolescent Sexual Development and Peer Groups: Reciprocal Associations and Shared Genetic and Environmental Influences

Peer groups influence the emergence of sexual behaviors in adolescence, but many details regarding the mechanisms underlying these effects have yet to be described. We examined the phenotypic, genetic, and environmental links between both antisocial and prosocial peer characteristics, and several sexual behaviors from middle childhood to late adolescence (ages 11, 14, and 17 years) using a longitudinal twin sample (N = 3762). Antisocial peers predicted greater engagement in both normative (e.g., dating) and non-normative (e.g., early sexual intercourse) sexual behaviors, while prosocial peers were associated with a lower likelihood of engaging in non-normative sexual behaviors. Reciprocal effects were also observed such that early sexual experiences were associated with a more antisocial and less prosocial peer groups later in adolescence. Behavioral genetic models indicated that most of the overlap between peer group characteristics and sexual behavior was due to shared environmental influences. That is, some features of the adolescent environment exert a press toward (or against) antisocial peers and sexual behaviors. Together, the results extend the existing literature by highlighting the ways through which peer affiliations are related to sexual development in adolescence.

First Sexual Intercourse in the Irish Study of Sexual Health and Relationships: Current Functioning in Relation to Age at Time of Experience and Partner Age

The Irish Study of Sexual Health and Relationships, based on a nationally representative sample of Republic of Ireland adults in 2004-2005, was used to examine adult adjustment in individuals who had their first sexual intercourse as a minor with an adult. Participants were classified into one of four groups based on their age at first intercourse and their partner's age: minors under 18 with peers; minors under 16 with adults; minors 16 to 17 with adults; and adults with adults. Adjustment (health, general relationships, satisfaction with most recent sexual partner, self-confidence, education and career achievement, and sexual problems) was compared across groups separately by gender. The vast majority of cases involved postpubertal heterosexual coitus. Overall, minors involved with adults were not significantly less well adjusted than adults involved with other adults on a majority of measures, effect size differences in adjustment were mostly small, and mean adjustment responses consistently indicated good rather than poor adjustment. Sex differences in first-intercourse characteristics and reasons for engaging reliably occurred for all age groups. In general, males compared to females were more willing, wanted more to lose their virginity, felt more ready for it, did it more often on the spur of the moment, and were less often involved in a relationship or in love when it occurred. Sex differences were greatest for boys versus girls under 16 with adults. Mediation and moderator analyses were also performed. Results were discussed in relation to competing perspectives on the effects of minor-adult sex.

Adolescent Big Five personality and pubertal development: Pubertal hormone concentrations and self-reported pubertal status

In early adolescence, levels of conscientiousness and agreeableness have been found to temporarily decrease, with levels of neuroticism increasing, indicating a dip in personality maturation. It is unknown whether these changes are related to the process of puberty, a major developmental milestone with numerous changes for children. Here, we first replicated the dip in personality maturity in early adolescence (N = 2640, age range 8-18, 51% girls, 65% non-Hispanic white, 21% Hispanic/Latino, 10% African American, 9% other, roughly 33% of families received means-tested public assistance) and tested associations between the Big Five personality dimensions and pubertal development and timing across late childhood and adolescence (n = 1793). Pubertal development was measured using both hormonal assays (DHEA, testosterone, and progesterone) and self-reports of secondary sex characteristics. Of hormonal measures, only higher DHEA concentrations were associated with lower conscientiousness and openness. Nonparametric moderation analyses using LOSEM indicated Complex Age × Sex interactions involving all three hormones. Self-reported pubertal development was associated with lower extraversion, conscientiousness, agreeableness, and openness. More advanced pubertal timing was also related to lower levels of extraversion, conscientiousness, and agreeableness. All associations were small. As some evidence was found for small associations between pubertal development and lower levels of conscientiousness and agreeableness, a dip in personality maturation in these personality traits may be partly due to pubertal development in early adolescence. Overall, results did not indicate that pubertal development was the primary explanation of the maturity dip in adolescent personality. Many small influences likely accumulate to explain the dip in personality maturity in early adolescence. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

A polygenic score for age-at-first-birth predicts disinhibition

BACKGROUND

A recent genome-wide association study identified molecular-genetic associations with age-at-first-birth. However, the meaning of these genetic discoveries is unclear. Drawing on evidence linking early pregnancy with disinhibitory behavior, we tested the hypothesis that genetic discoveries for age-at-first-birth predict disinhibition.

METHODS

We included participants with genotype data from the two-decade-long Environmental Risk (E-Risk) Study (N = 1,999) and the four-decade-long Dunedin Study (N = 918). We calculated a genome-wide polygenic score for age-at-first-birth and tested whether it was associated with a range of disinhibitory outcomes across the life course, including low childhood self-control; risk for externalizing psychopathology; officially recorded criminal offending; substance dependence; informant reports of disinhibitory problems; and number of lifetime sexual partners. We further tested whether associations were attributable to accelerated pubertal maturation.

RESULTS

In both cohorts, the age-at-first-birth polygenic score predicted low childhood self-control, externalizing psychopathology, officially recorded criminal offending, substance dependence, and number of sexual partners. Associations were modest, but robust across replication. Childhood disinhibition partly mediated associations between the polygenic score and reproductive behaviors. In contrast, associations were not attributable to accelerated pubertal timing.

CONCLUSIONS

Genomic discoveries for age-at-first-birth are about more than reproductive biology: They provide insight into the disinhibitory traits and behaviors that accompany early parenthood. Age-at-first-birth is a useful proxy phenotype for researchers interested in disinhibition. Further, interventions that improve self-regulation abilities may benefit young parents and their children.

Biological aging in childhood and adolescence following experiences of threat and deprivation: A systematic review and meta-analysis

Life history theory argues that exposure to early life adversity (ELA) accelerates development, although existing evidence for this varies. We present a meta-analysis and systematic review testing the hypothesis that ELA involving threat (e.g., violence exposure) will be associated with accelerated biological aging across multiple metrics, whereas exposure to deprivation (e.g., neglect, institutional rearing) and low-socioeconomic status (SES) will not. We meta-analyze 54 studies (n = 116,010) examining associations of ELA with pubertal timing and cellular aging (telomere length and DNA methylation age), systematically review 25 studies (n = 3,253) examining ELA and neural markers of accelerated development (cortical thickness and amygdala-prefrontal cortex functional connectivity) and evaluate whether associations of ELA with biological aging vary according to the nature of adversity experienced. ELA overall was associated with accelerated pubertal timing (d = -0.10) and cellular aging (d = -0.21), but these associations varied by adversity type. Moderator analysis revealed that ELA characterized by threat was associated with accelerated pubertal development (d = -0.26) and accelerated cellular aging (d = -0.43), but deprivation and SES were unrelated to accelerated development. Systematic review revealed associations between ELA and accelerated cortical thinning, with threat-related ELA consistently associated with thinning in ventromedial prefrontal cortex, and deprivation and SES associated with thinning in frontoparietal, default, and visual networks. There was no consistent association of ELA with amygdala-PFC connectivity. These findings suggest specificity in the types of early environmental experiences associated with accelerated biological aging and highlight the importance of evaluating how accelerated aging contributes to health disparities and whether this process can be mitigated through early intervention. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

Integrating Individual and Contextual Factors to Explain Disparities in HIV/STI Among Heterosexual African American Youth: A Contemporary Literature Review and Social Ecological Model

Heterosexual African American youth face substantial disparities in sexual health consequences such as HIV and STI. Based on the social ecological framework, the current paper provides a comprehensive, narrative review of the past 14 years of literature examining HIV/STI risk, including risky sexual behavior, among heterosexual African American youth and a conceptual model of risk among this population. The review found that individual psychological and biological factors are insufficient to explain the sexual health disparities faced by this group; instead, structural disadvantage, interpersonal risk, and community dysfunction contribute to the disparity in HIV/STI outcomes directly and indirectly through individual psychological factors. The conceptual model presented suggests that for African American youth, (1) HIV/STI risk commonly begins at the structural level and trickles down to the community, social, and individual levels, (2) risk works in a positive feedback system such that downstream effects compound the influence of structural risks, and (3) contextual and individual risk factors must be considered within the advanced stage of the epidemic facing this population. Despite advanced HIV and STI epidemics among heterosexual African American youth, multisystemic interventions that target structural risk factors and their downstream effects are posited to reduce the disparity among this high-risk population.

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.

Gene Polymorphisms Affecting Erectile Dysfunction

INTRODUCTION

Erectile dysfunction (ED) is usually developed from psychological, neurological, hormonal, and vascular pathologies or a combination of these factors. However, the possible genetic polymorphisms that might underlie this disorder were not thoroughly investigated.

OBJECTIVES

This review article aimed to assess the possible involvement of gene polymorphisms in men with ED.

METHODS

A systematic review was conducted until January 2020 based on a search of all relevant articles in many electronic sites such as PubMed, Medline Medical Subject Headings, Science Direct, Scopus, Cochrane Library, EMBASE, CINAHL, and Egyptian Knowledge Bank databases with no language restriction. Keywords used to assess the outcome and estimates for relevant associations were sexual health, genes, erectile dysfunction, polymorphisms, and cavernous tissues.

RESULTS

Many genetic studies were carried out to inspect the contribution of different encoded genotypes and ED. Overall, 50 studies were reviewed and were classified as per the type of gene polymorphisms. These studies have investigated 10,174 men with ED compared with 6,891 healthy men as controls. 35 studies were case-controlled, 13 cross-sectional cohort studies, one retrospective study, and one genome-wide association study. So far, the most relevant gene polymorphisms linked with men with ED included endothelial nitric oxide synthase (eNOS), angiotensin-converting enzyme (ACE), androgen receptor (AR) CAG repeat, G-protein β3 (GNB3) subunit, methylenetetrahydrofolate reductase (MTHFR), vascular endothelial growth factor (VEGF), TGFB1, proprotein convertase subtilisin/kexin type 9 (PCSK9), ARG1, DRD2, DRD4, DDAH, and HNF4A genes. Both PROGINS and IGFBP-3 polymorphisms were investigated in only one study each but with irrelevant significance.

CONCLUSIONS

Although several genetic studies exposed the association between different genotypes and men with ED with varied outcomes, such a relationship should not be overlooked. Therefore, more studies should be encouraged to elucidate the exact role, if any, for such association. Mostafa T, Taymour M. Gene Polymorphisms Affecting Erectile Dysfunction. Sex Med 2020;8:561-572.

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 biological basis of sexual orientation: How hormonal, genetic, and environmental factors influence to whom we are sexually attracted

Humans develop relatively stable attractions to sexual partners during maturation and present a spectrum of sexual orientation from homosexuality to heterosexuality encompassing varying degrees of bisexuality, with some individuals also displaying asexuality. Sexual orientation represents a basic life phenomenon for humans. However, the molecular mechanisms underlying these diverse traits of sexual orientation remain highly controversial. In this review, we systematically discuss recent advancements in sexual orientation research, including those related to measurements and associated brain regions. Current findings regarding sexual orientation modulation by hormonal, genetic, maternal immune system, and environmental factors are summarized in both human and model systems. We also emphasize that future studies should recognize the differences between males and females and pay more attention to minor traits and the epigenetic regulation of sexual orientation. A comprehensive view of sexual orientation may promote our understanding of the biological basis of sex, and that of human reproduction, and evolution.

Kids becoming less alike: A behavioral genetic analysis of developmental increases in personality variance from childhood to adolescence

Recent work in personality development has indicated that the magnitude of individual differences in personality increases over child development. Do such patterns reflect the differentiation of individuals by genotype, an increasing influence of environmental factors, or some (interactive) combination of the two? Using a population-based sample of over 2,500 twins and multiples from the Texas Twin Project, we estimated age trends in the variances in self- and parent-reported measures of the Big Five personality traits between Ages 8 and 18 years. We then estimated age trends in the genetic and environmental components of variance in each measure. Individual differences in personality increased in magnitude from childhood through mid-adolescence. This pattern emerged using both children's self-reports and ratings provided by their parents, and was primarily attributable to increases in the magnitude of genetic influences. Most of the increasing genetic variance appeared nonadditive, pointing to the possibility that developmental processes tend to make genetically similar individuals disproportionately more alike in their personality traits over time. These findings could reflect increasing or accumulating effects of trait-by-trait interactions; person-by-environment transactions, whereby genetically similar people are disproportionally likely to experience similar environments; the activation of dominant genes across developmental transitions (e.g., puberty); or some combination of these three processes, among other factors. Theories of personality development will need to accommodate these descriptive findings, and longitudinal, genetically informed designs are needed to test some of the specific hypotheses springing from this study. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Catechol-O-Methyltransferase Val158Met and brain-derived neurotrophic factor Val66Met gene polymorphisms in paraphilic sexual offenders

BACKGROUND

Child sexual abuse (CSA) is an important problem worldwide. The reason of sex abuse is considered as multifactorial. Genetic contribution reported by recent studies is a significant evidence for this pathologic behavior. Catechol-O-Methyltransferase (COMT) is an enzyme in the metabolic inactivation of catecholamine and substances containing catecholamines such as dopamine, epinephrine, and norepinephrine. COMT polymorphism causes functional changes in COMT enzyme activity. Brain-derived neurotrophic factor (BDNF) is a neurotrophic factor usually synthesized from central nervous system neurons. With the effect of BDNF, dopamine and serotonin play important roles on neurogenesis, survival, and synaptic plasticity.

AIM

This study aims to examine COMT Val158Met (rs4680) and BDNF Val66Met (rs6265) polymorphisms in CSA.

SETTINGS AND DESIGN

This was a case-control study.

MATERIALS AND METHODS

Seventy paraphilic child sexual abuser patients and seventy age- and gender-matched healthy controls participated in this study. COMT Val158Met and BDNF Val66Met polymorphisms were genotyped by real-time polymerase chain reaction assay.

RESULTS

COMT Val158Met genotype frequencies were determined as GG 31.4%, GA 45.7%, and AA 22.9% in patients; GG 24.3%, GA 45.7%, and AA 8.6% in controls; and exhibited a positive relationship between the groups (P = 0.018). BDNF Val66Met genotype frequencies were determined as GG 77.1%, GA 21.4%, and AA 1.4% in patients; GG 65.7%, GA 31.4%, AA 2.9% in controls; and no significant relationship was observed between the groups (P = 0.317).

CONCLUSIONS

This research investigated COMT (Val158Met) and BDNF (Val66Met) in paraphilic child sexual offenders. A positive relationship was found for COMT gene; however, no significant relation was observed for BDNF gene between paraphilic sexual offenders and controls.

Approach and Avoidance Biases Toward Sexual Stimuli and Their Association with the Dual Control Model of Sexual Response in Heterosexual Men

Many models of human behavior work in an interaction of a dual system. While one system usually represents controlled and reflective behavioral responses, the other system reflects automatic and impulsive actions. In the impulsive system, positive stimuli initiate approach reactions and negative cues avoidance reactions. Besides stimulus valence, the behavioral response triggered by the impulsive system is influenced by personality (e.g., the propensity to react with approach or avoidance biases in a specific situation). The present study applied a computerized Approach-Avoidance Task (AAT; Rinck & Becker, 2007) to assess automatic behavioral approach and avoidance biases toward sexual and neutral stimuli in heterosexual men (N = 40). Individual AAT-performance was furthermore related to sexual excitation (SES) and the two sexual inhibition factors (SIS1 and SIS2) as proposed by the Dual Control Model of sexual response (Bancroft & Janssen, 2000). Against our hypotheses, participants did not show a stronger approach bias toward sexually preferred (i.e., images of women) than sexually not preferred stimuli (i.e., images of men or children). However, stronger approach biases toward images of women were positively associated with sexual excitation and negatively correlated with sexual inhibition due to a threat of performance failure (SIS1) even after controlling for potential confounds (i.e., general behavioral activation and inhibition). The results support the importance of the influence of dispositional traits measured with the Dual Control Model of sexual response on approach and avoidance biases toward sexually preferred stimuli in heterosexual men.

Associations between Parental Psychopathology and Sexual Behavior in an Outpatient Psychiatric Sample

Early age of sexual debut is associated with an increase in negative outcomes, including higher incidence of nonconsensual sexual experiences, higher rates of sexually transmitted infections, and risky sexual practices. Little research has examined the role of parental psychopathology as a predictor of adolescent sexual activity, however. The current study aims to close this gap by examining the relationship between parental psychopathology and sexual activity in a longitudinal sample of youth. Participants were 685 adolescents from the Longitudinal Assessment of Manic Symptoms study, the majority of whom were male (67%) and White (65%). Analyses considering likelihood of sexual initiation included the full sample, whereas analyses considering predictors of the age of sexual debut included the 162 participants who reported ever having sexual intercourse (62% male, 51% White) via the Youth Risk Behavior Surveillance-High School version. Cox regression analyses suggested that maternal generalized anxiety disorder predicted decreased likelihood of initiating sex during the 8-year follow-up period, whereas paternal conduct disorder predicted increased likelihood of initiating sex. Multivariate linear regressions also showed that maternal conduct disorder predicted earlier age of sexual debut among those who had initiated, whereas paternal antisocial personality disorder predicted later age of sexual debut. These associations were observed in both male and female adolescents. Furthermore, these effects were largely not explained by the established relationship between youth psychopathology and sexual behavior. Results have implications for interventions aimed at decreasing sexual risk taking in vulnerable youth.

Risky Sexual Behaviors and Pregnancy Outcomes in Young Adulthood Following Substantiated Childhood Maltreatment: Findings From a Prospective Birth Cohort Study

Childhood maltreatment is associated with a range of adverse mental and physical health outcomes, including increased rates of sexually transmitted infections (STIs) later in life. However, the impact on risky sexual behaviors and pregnancy outcomes has not been adequately studied. This is particularly true for physical abuse, emotional abuse, and neglect. We examined associations between prospectively substantiated childhood maltreatment and reports of risky sexual behaviors by men and women, as well as selected pregnancy outcomes in women. We followed up 3,081 (45.7% female) participants from the Mater-University of Queensland Study of Pregnancy, a prospective Australian birth cohort study. Using logistic regression, we examined the association between substantiated childhood maltreatment from birth to 14 years, and self-reported risky sexual behaviors and youth pregnancy outcomes at the 21-year follow-up. In adjusted analyses, children who had experienced multiple childhood maltreatment exhibited more risky sexual behaviors than their nonmaltreated counterparts. In specific models, those exposed to each form of childhood maltreatment, independent of co-occurring forms of childhood maltreatment, had an increased likelihood of risky sexual behaviors, particularly an early sexual debut and, for women, youth pregnancy. Neglect was also associated with multiple sexual partners, and emotional abuse with higher rates of miscarriage. There was no difference between men and women in how different forms of childhood maltreatment predicted risky sexual behaviors in young adulthood. All forms of substantiated childhood maltreatment, including multiple substantiations, were associated with risky sexual behavior in both sexes as well as higher rates of youth pregnancy in women. Moreover, emotional abuse persistently predicted miscarriages in young adult women. Understanding the association between childhood maltreatment and risky sexual behaviors and youth pregnancy outcomes may help suggest preventive strategies.

Decomposing environmental unpredictability in forecasting adolescent and young adult development: A two-sample study

To illuminate which features of an unpredictable environment early in life best forecast adolescent and adult functioning, data from two longitudinal studies were examined. After decomposing a composite unpredictability construct found to predict later development, results of both studies revealed that paternal transitions predicted outcomes more consistently and strongly than did residential or occupational changes across the first 5 years of a child's life. These results derive from analyses of the NICHD Study of Early Child Care and Youth Development, which included diverse families from 10 different sites in the United States, and from the Minnesota Longitudinal Study of Risk and Adaptation, whose participants came from one site, were disproportionately economically disadvantaged, and were enrolled 15 years earlier than the NICHD Study sample. The finding that results from both studies are consistent with evolutionary, life history thinking regarding the importance of males in children's lives makes this general, cross-study replication noteworthy.

Early Sexual Initiation and Mental Health: A Fleeting Association or Enduring Change?

The present research examined how the within-person association between sexual initiation and internalizing symptoms decays over time, using data with annual measurement occasions across adolescence (N = 1,789) and statistical models of within-person change. Sexual initiation was associated with increased levels of internalizing symptoms for early-initiating girls (ninth grade, approximately age 15), but not for on-time-initiating girls or for boys. The association between girls' early sexual initiation and internalizing symptoms declined precipitously over time. Indeed, 1 year after sexual debut, early-initiating girls were similar to on-time or noninitiating girls on internalizing symptoms, suggesting early sexual initiation does not produce lasting detriments to girls' mental health. Findings inform how researchers perceive sexual initiation, both as a developmental milestone and as a prevention target.

Father's death does not affect growth and maturation but hinders reproduction: evidence from adolescent girls in post-war Estonia

The popular concept of predictive-adaptive responses poses that girls growing up without a father present in the family mature and start reproduction earlier because the father's absence is a cue for environmental harshness and uncertainty that favours switching to a precocious life-history strategy. Most studies supporting this concept have been performed in situations where the father's absence is caused by divorce or abandonment. Using a dataset of Estonian adolescent girls who had lost their fathers over the period of World War II, we show that father's death did not affect the rate of pubertal maturation (assessed on the basis of development of breasts and axillary hair) or growth. Father's death did not affect the age of first birth but, contrary to predictions, reduced lifetime reproductive success. Our findings thus do not support the concept of predictive-adaptive responses and suggest that alternative explanations for covariation between fatherlessness and early maturation are required.

Gender differences in the association between childhood sexual abuse and risky sexual behaviours: A systematic review and meta-analysis

This meta-analytic review examines the association between childhood sexual abuse and risky sexual behaviours with sub-group analyses by gender. Systematic searches of electronic databases including MEDLINE, PubMed, EMBASE, and PsycINFO were performed using key terms. We used a priori criteria to include high quality studies and control for heterogeneities across eligible studies. The review was registered with PROSPERO and used the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. The final meta-analysis applied fixed-effects model to generate pooled odds ratio (OR). Subgroup analyses were conducted to identify potential methodological moderators. The meta-analysis included 8 eligible studies (N=38,989, females=53.1%). The overall syndemic of risky sexual behaviors at adulthood was 1.59 times more common in childhood sexual abuse victims. There was a similar association between childhood sexual abuse in general and subsequent risky sexual behaviors in both females and males. However, in cases of substantiated childhood sexual abuse, there was a greater odds of risky sexual behaviors in females (OR=2.72) than males (OR=1.69). The magnitude of association of childhood sexual abuse and risky sexual behaviors was similar for males and females regardless of study time, study quality score and method of childhood sexual abuse measurement. There were nonsignificant overall and subgroup differences between males and females. Childhood sexual abuse is a significant risk factor for a syndemic of risky sexual behaviors and the magnitude is similar both in females and males. More research is needed to explore possible mechanisms of association.

Harsh Parenting, Deviant Peers, Adolescent Risky Behavior: Understanding the Meditational Effect of Attitudes and Intentions

Although research supports the influence of parents and peers on adolescent risky behavior, less is known about mechanisms proposed to explain this relation. This study examined the influence of adolescent attitudes and intentions about such behaviors. Prospective, longitudinal data came from rural youth who participated throughout adolescence (n= 451). Observed harsh parenting and relationship with deviant peers was assessed in early adolescence, attitudes and intentions were measured during middle adolescence, and risky behavior was assessed in late adolescence. Results indicated that parenting and deviant peers was related to engagement in tobacco use, alcohol use, and risky sexual behaviors. Moreover, attitudes and intentions mediated this relationship even after parent use and adolescent early involvement in these behaviors were taken into account.

What Explains the Heritability of Completed Fertility? Evidence from Two Large Twin Studies

In modern societies, individual differences in completed fertility are linked with genotypic differences between individuals. Explaining the heritability of completed fertility has been inconclusive, with alternative explanations centering on family formation timing, pursuit of education, or other psychological traits. We use the twin subsample from the Midlife Development in the United States study and the TwinsUK study to examine these issues. In total, 2606 adult twin pairs reported on their completed fertility, age at first birth and marriage, level of education, Big Five personality traits, and cognitive ability. Quantitative genetic Cholesky models were used to partition the variance in completed fertility into genetic and environmental variance that is shared with other phenotypes and residual variance. Genetic influences on completed fertility are strongly related to family formation timing and less strongly, but significantly, with psychological traits. Multivariate models indicate that family formation, demographic, and psychological phenotypes leave no residual genetic variance in completed fertility in either dataset. Results are largely consistent across U.S. and U.K. sociocultural contexts.

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.

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.

Genetic influence on age at first birth of female twins born in the UK, 1919-68

Using a sample of monozygotic (945, 42 per cent) and dizygotic (1,329, 58 per cent) twin pairs born 1919-68 in the UK, we applied innovative tobit models to investigate genetic and environmental influences on age at first birth (AFB). We found that a substantial part (40 per cent) of the variation in AFB is caused by latent family characteristics. Genetic dispositions (26 per cent) play a more important role than the shared environment of siblings (14 per cent), with the non-shared environment/measurement error having the strongest influence (60 per cent). Like previous studies, this study reveals marked changes in estimates over time, and supports the idea that environmental constraints (war or economic crisis) suppress and normative freedom (sexual revolution) promotes the activation of genetic predispositions that affect fertility. We show that the exclusion of censored information (i.e., on the childless) by previous studies biased their results.

Clarifying the associations between age at menarche and adolescent emotional and behavioral problems

Better understanding risk factors for the development of adolescent emotional and behavioral problems can help with intervention and prevention efforts. Previous studies have found that an early menarcheal age predicts several adolescent problems, including depressive symptoms, delinquency, and early age at first intercourse. Few studies, nevertheless, have explicitly tested (a) whether the associations with menarcheal age vary across racial/ethnic groups or (b) whether the sources of the associations are within-families (i.e., consistent with a direct, causal link) or only between-families (i.e., due to selection or confounding factors). The current study analyzed data from a nationally representative US Sample of females (N = 5,637). We examined whether race/ethnicity moderated the associations between early menarche and several adolescent problems by using multiple-group analyses and we examined the degree to which genetic and environmental factors shared by family members account for the associations by comparing sisters and cousins with differing menarcheal ages. Menarcheal age predicted subsequent depressive symptoms, delinquency, and early age at first intercourse in the population. The magnitudes of the associations were similar across all racial/ethnic groups for all outcomes. The within-family associations (i.e., when comparing siblings and cousins with different menarcheal age) were large and statistically significant when predicting early intercourse, but not the other outcomes. The findings suggest that selection or confounding factors account for the associations between menarcheal age and subsequent depressive symptoms and delinquency, whereas the independent association between menarcheal age and early age at first intercourse is consistent with a direct, causal effect.

Genotype × cohort interaction on completed fertility and age at first birth

Microevolutionary projections use empirical estimates of genetic covariation between physical or psychological phenotypes and reproductive success to forecast changes in the population distributions of those phenotypes over time. The validity of these projections depends on relatively consistent heritabilities of fertility-relevant outcomes and consistent genetic covariation between fertility and other physical or psychological phenotypes across generations. However, well-documented, rapidly changing mean trends in the level and timing of fertility may have been accompanied by differences in the genetic mechanisms of fertility. Using a sample of 933 adult twin pairs from the Midlife Development in the United States study, we demonstrate that genetic influences on completed fertility and age at first birth were trivial for the 1920-1935 birth cohort, but rose substantially for the 1936-1955 birth cohort. For the 1956-1970 birth cohort, genetic influences on completed fertility, but not age at first birth, persisted. Because the heritability of fertility is subject to change dynamically with the social context, it is difficult to project selection pressures or the rate at which selection will occur.

Maternal age at childbirth and risk for ADHD in offspring: a population-based cohort study

BACKGROUND

Women who give birth at younger ages (e.g. teenage mothers) are more likely to have children who exhibit behaviour problems, such as attention-deficit/hyperactivity disorder (ADHD). However, it is not clear whether young maternal age is causally associated with poor offspring outcomes or confounded by familial factors.

METHODS

The association between early maternal age at childbirth and offspring ADHD was studied using data from Swedish national registers. The sample included all children born in Sweden between 1988 and 2003 (N = 1 495 543), including 30 674 children with ADHD. We used sibling- and cousin-comparisons to control for unmeasured genetic and environmental confounding. Further, we used a children-of-siblings model to quantify the genetic and environmental contribution to the association between maternal age and offspring ADHD.

RESULTS

Maternal age at first birth (MAFB) was associated with offspring ADHD. Teenage childbirth (<20 years) was associated with 78% increased risk of ADHD. The association attenuated in cousin-comparison, suggesting unmeasured familial confounding. The children-of-siblings model indicated that the association between MAFB and ADHD was mainly explained by genetic confounding.

CONCLUSIONS

All children born to mothers who bore their first child early in their reproductive lives were at increased risk of ADHD. The association was mainly explained by genetic factors transmitted from mothers to their offspring that contribute to both age at childbirth and ADHD in offspring. Our results highlight the importance of using family-based designs to understand how early life circumstances affect child development.

Child characteristics and parental educational expectations: evidence for transmission with transaction

Parents' expectations for their children's ultimate educational attainment have been hypothesized to play an instrumental role in socializing academically relevant child behaviors, beliefs, and abilities. In addition to social transmission of educationally relevant values from parents to children, parental expectations and child characteristics may transact bidirectionally. We explore this hypothesis using both longitudinal and genetically informative twin data from the Early Childhood Longitudinal Study-Birth and Kindergarten cohorts. Our behavior genetic results indicate that parental expectations partly reflect child genetic variation, even as early as 4 years of age. Two classes of child characteristics were hypothesized to contribute to these child-to-parent effects: behavioral tendencies (approaches toward learning and problem behaviors) and achievement (math and reading). Using behavior genetic models, we find within-twin-pair associations between these child characteristics and parental expectations. Using longitudinal cross-lagged models, we find that initial variation in child characteristics predicts future educational expectations above and beyond previous educational expectations. These results are consistent with transactional frameworks in which parent-to-child and child-to-parent effects co-occur.

A Noncausal Relation Between Casual Sex in Adolescence and Early Adult Depression and Suicidal Ideation: A Longitudinal Discordant Twin Study

Research on relations between casual sex and mental health is inconclusive; while some studies indicate casual sex may lead to more negative mental health (e.g., depression), other studies report no such relationship. Using a genetically informed approach, this study examined whether earlier casual sex (i.e., ever engaging in casual sex and number of casual sex partners) in adolescence has a causal influence on later mental health in young adulthood (i.e., depressive symptoms and suicidal ideation), as well as the reverse relationship (adolescent negative mental health on young adult casual sex) by exploiting the quasi-experimental nature of discordant-twin models. Multilevel models that measured within-twin and between-twin pair effects of adolescent casual sex were estimated, using 714 twins (357 twin pairs) from the sibling subsample of the National Longitudinal Study of Adolescent Health (Add Health). Results indicated that there was no causal relationship between casual sex in adolescence and higher levels of depressive symptoms or suicidal ideation in young adulthood, and these effects did not differ by gender. There were also no causal relations between adolescent depressive symptoms or suicidal ideation and casual sexual experience in young adulthood. Implications for ways to increase scientific rigor by using different methods (e.g., genetically informed analyses) are discussed.

The age gauge: older fathers having children

In recent years, scientists have debated the existence of a link between a father’s age and his child’s vulnerability to psychiatric problems. Our authors led a research team that produced a paper that analyzed data on all individuals born in Sweden from 1973 through 2001. Both the authors’ study and another study raise as many questions as they answer, but they suggest that children born to middle-aged men are more likely than their older siblings to develop a range of mental difficulties, including bipolar disorder, autism, and schizophrenia.