Gene-environment correlation underlying the association between parental negativity and adolescent externalizing problems

Studies of adolescent or parent-based twins suggest that gene-environment correlation (rGE) is an important mechanism underlying parent-adolescent relationships. However, information on how parents' and children's genes and environments influence correlated parent and child behaviors is needed to distinguish types of rGE. The present study used the novel Extended Children of Twins model to distinguish types of rGE underlying associations between negative parenting and adolescent (age 11-22 years) externalizing problems with a Swedish sample of 909 twin parents and their adolescent offspring and a U.S.-based sample of 405 adolescent siblings and their parents. Results suggest that evocative rGE, not passive rGE or direct environmental effects of parenting on adolescent externalizing, explains associations between maternal and paternal negativity and adolescent externalizing problems.

Genetic vulnerability interacts with parenting and early care education to predict increasing externalizing behavior

The current study examined interactions among genetic influences and children's early environments on the development of externalizing behaviors from 18 months to 6 years of age. Participants included 233 families linked through adoption (birth parents and adoptive families). Genetic influences were assessed by birth parent temperamental regulation. Early environments included both family (overreactive parenting) and out-of-home factors (center-based Early Care and Education; ECE). Overreactive parenting predicted more child externalizing behaviors. Attending center-based ECE was associated with increasing externalizing behaviors only for children with genetic liability for dysregulation. Additionally, children who were at risk for externalizing behaviors due to both genetic variability and exposure to center-based ECE were more sensitive to the effects of overreactive parenting on externalizing behavior than other children.

Biological and rearing mother influences on child ADHD symptoms: revisiting the developmental interface between nature and nurture

BACKGROUND

Families of children with attention deficit hyperactivity disorder (ADHD) report more negative family relationships than families of children without ADHD. Questions remain as to the role of genetic factors underlying associations between family relationships and children's ADHD symptoms, and the role of children's ADHD symptoms as an evocative influence on the quality of relationships experienced within such families. Utilizing the attributes of two genetically sensitive research designs, the present study examined associations between biologically related and nonbiologically related maternal ADHD symptoms, parenting practices, child impulsivity/activation, and child ADHD symptoms. The combined attributes of the study designs permit assessment of associations while controlling for passive genotype-environment correlation and directly examining evocative genotype-environment correlation (rGE); two relatively under examined confounds of past research in this area.

METHODS

A cross-sectional adoption-at-conception design (Cardiff IVF Study; C-IVF) and a longitudinal adoption-at-birth design (Early Growth and Development Study; EGDS) were used. The C-IVF sample included 160 mothers and children (age 5-8 years). The EGDS sample included 320 linked sets of adopted children (age 6 years), adoptive-, and biologically related mothers. Questionnaires were used to assess maternal ADHD symptoms, parenting practices, child impulsivity/activation, and child ADHD symptoms. A cross-rater approach was used across measures of maternal behavior (mother reports) and child ADHD symptoms (father reports).

RESULTS

Significant associations were revealed between rearing mother ADHD symptoms, hostile parenting behavior, and child ADHD symptoms in both samples. Because both samples consisted of genetically unrelated mothers and children, passive rGE was removed as a possible explanatory factor underlying these associations. Further, path analysis revealed evidence for evocative rGE processes in the longitudinal adoption-at-birth study (EGDS) from biologically related maternal ADHD symptoms to biologically unrelated maternal hostile parenting through early disrupted child behavior (impulsivity/activation), with maternal hostile parenting and disrupted child behavior associated with later child ADHD symptoms, controlling for concurrent adoptive mother ADHD symptoms.

CONCLUSIONS

Results highlight the importance of genetically influenced child ADHD-related temperamental attributes on genetically unrelated maternal hostility that in turn links to later child ADHD symptoms. Implications for intervention programs focusing on early family processes and the precursors of child ADHD symptoms are discussed.

Maternal smoking during pregnancy and offspring conduct problems: evidence from 3 independent genetically sensitive research designs

IMPORTANCE

Several studies report an association between maternal smoking during pregnancy and offspring conduct disorder. However, past research evidences difficulty in disaggregating prenatal environmental influences from genetic and postnatal environmental influences.

OBJECTIVE

To examine the relationship between maternal smoking during pregnancy and offspring conduct problems among children reared by genetically related mothers and genetically unrelated mothers.

DESIGN, SETTING, AND PARTICIPANTS

The following 3 studies using distinct but complementary research designs were used: The Christchurch Health and Development Study (a longitudinal cohort study that includes biological and adopted children), the Early Growth and Development Study (a longitudinal adoption-at-birth study), and the Cardiff IVF (In Vitro Fertilization) Study (an adoption-at-conception study among genetically related families and genetically unrelated families). Maternal smoking during pregnancy was measured as the mean number of cigarettes per day (0, 1-9, or 10) smoked during pregnancy. Possible covariates were controlled for in the analyses, including child sex, birth weight, race/ethnicity, placement age, and breastfeeding, as well as maternal education and maternal age at birth and family breakdown, parenting practices, and family socioeconomic status.

MAIN OUTCOMES AND MEASURE

Offspring conduct problems (age range, 4-10 years) reported by parents or teachers using the behavior rating scales by Rutter and Conners, the Child Behavior Checklist and the Children's Behavior Questionnaire Short Form, and the Strengths and Difficulties Questionnaire.

RESULTS

A significant association between maternal smoking during pregnancy and offspring conduct problems was observed among children reared by genetically related mothers and genetically unrelated mothers. Results from a meta-analysis affirmed this pattern of findings across pooled study samples.

CONCLUSIONS AND RELEVANCE

Findings across 3 studies using a complement of genetically sensitive research designs suggest that smoking during pregnancy is a prenatal risk factor for offspring conduct problems when controlling for specific perinatal and postnatal confounding factors.

How genes and the social environment moderate each other

Recent research has suggested that the social environment can moderate the expression of genetic influences on health and that genetic influences can shape an individual's sensitivity to the social environment. Evidence supports 4 major mechanisms: genes can influence an individual's response to environmental stress, genes may enhance an individual's sensitivity to both favorable and adverse environments, inherited characteristics may better fit with some environments than with others, and inherited capabilities may only become manifest in challenging or responsive environments. Further progress depends on better recognition of patterns of gene-environment interaction, improved methods of assessing the environment and its impact on genetic mechanisms, the use of appropriately designed laboratory studies, identification of heritable differences in an individual before environmental moderation occurs, and clarification of the timing of the impact of social and genetic moderation.

Measurement and associations of pregnancy risk factors with genetic influences, postnatal environmental influences, and toddler behavior

This study demonstrates the unique contributions of perinatal risk and genetic and environmental influences on child behavior using data from 561 domestic US adoption triads (birth mothers, adopted child, and adoptive parents). Findings show distinct patterns of associations among genetic (birth mother psychopathology), prenatal (six maternal reported aggregate scores characterizing total obstetric complications, perinatal internalizing symptoms, pregnancy complications, exposure to toxins, substance use, and neonatal complications), and postnatal influences (adoptive parent 18-month internalizing symptoms and over-reactive parenting) and toddler behavior problems (CBCL subscales at 27 months). Findings highlight multiple pathways for toddler's behavioral development, including genetic, pregnancy, and postnatal main effects. Findings suggest distinct types of pregnancy risk may transmit genetic influences for specific behavior problems rather than broadband problems.

The observed association between maternal anxiety and adolescent asthma: children of twin design suggest familial effects

Background

Previous studies indicate that maternal anxiety is associated with asthma in the adolescent child, but mechanisms are unclear.

Objective

To investigate the association between maternal anxiety and maternal, self- and register-based report of asthma in the adolescent child, and whether the association remains after control of familial confounding (shared environmental and genetic factors).

Method

From the Twin and Offspring Study of Sweden, 1691 mothers (1058 twins) and their adolescent child were included. The association between maternal self-reported anxiety (Beck Anxiety Inventory (BAI) and Karolinska Scales of Personality (KSP) somatic or psychic anxiety) and asthma based on subjective (maternal or child report) or objective (register-based diagnosis and medication) measures were analysed using logistic regression. The children-of-twins design was used to explore whether genes or environment contribute to the association.

Results

Maternal BAI anxiety (OR 2.02, CI 1.15–3.55) was significantly associated with adolescent asthma reported by the mother. Maternal KSP somatic anxiety (OR 1.74, CI 1.04–2.91) and psychic anxiety (OR 1.74, CI 1.05–2.86) was significantly associated with breathlessness reported by the adolescent child. In contrast, maternal anxiety was not associated with increased risk for the register-based outcomes of asthma diagnosis or medication. The results remained also after adjusting for covariates and the children-of-twins analyses which indicate that the association was due to familial confounding.

Conclusions

We found some associations between maternal anxiety and subjectively reported offspring asthma or breathlessness which may be due to familial effects. A likely candidate for explaining this familial confounding is heritable personality traits associated with both anxiety and subjective measures of asthma.

Using an adoption design to separate genetic, prenatal, and temperament influences on toddler executive function

Poor executive functioning has been implicated in children's concurrent and future behavioral difficulties, making work aimed at understanding processes related to the development of early executive function (EF) critical for models of developmental psychopathology. Deficits in EF have been associated with adverse prenatal experiences, genetic influences, and temperament characteristics. However, our ability to disentangle the predictive and independent effects of these influences has been limited by a dearth of genetically informed research designs that also consider prenatal influences. The present study examined EF and language development in a sample of 361 toddlers who were adopted at birth and reared in nonrelative adoptive families. Predictors included genetic influences (as inherited from birth mothers), prenatal risk, and growth in child negative emotionality. Structural equation modeling indicated that the effect of prenatal risk on toddler effortful attention at age 27 months became nonsignificant once genetic influences were considered in the model. In addition, genetic influences had unique effects on toddler effortful attention. Latent growth modeling indicated that increases in toddler negative emotionality from 9 to 27 months were associated with poorer delay of gratification and poorer language development. Similar results were obtained in models incorporating birth father data. Mechanisms of intergenerational transmission of EF deficits are discussed.

Transactions between child social wariness and observed structured parenting: evidence from a prospective adoption study

This investigation examined the mutual influences between structured parenting and child social wariness during toddlerhood using a longitudinal adoption design. The sample consisted of 361 adoption-linked families, each including an adopted child, adoptive parents, and a birth mother. Heightened social wariness in children at age 18 months predicted reduced levels of observed structured parenting (i.e., less directive parenting with fewer commands and requests) in adoptive mothers at age 27 months. Adoptive fathers' lower structured parenting at age 18 months predicted subsequent elevation in child social wariness. Birth mothers' history of fear-related anxiety disorders was not associated with child social wariness. Findings highlight the role of dynamic family transactions in the development of social wariness during toddlerhood.

Marital adjustment as a moderator for genetic and environmental influences on parenting

Family systems theory proposes that the parent-child relationship is embedded within the broader system of the family, and that other family subsystems can influence the dynamics and quality of the parent-child relationship. The current paper examines marital adjustment as a context for the parent-child relationship during adolescence. Specifically, the extent to which marital adjustment moderates child-based genetic and environmental effects on the parent-child relationship was assessed. Data for this study were from the initial wave of the Nonshared Environment in Adolescent Development (NEAD) study, and included 720 families with same-sex sibling pairs, ages 10-18 years. A range of sibling and family types was sampled, with 93 monozygotic twin pairs, 99 dizygotic twin pairs, and 95 sibling pairs from nondivorced families, and 182 sibling, 109 half-sibling, and 130 unrelated sibling pairs from stepfamilies. Composite measures of marriage (based on parent reports) and parenting (based child and parent reports and observation ratings) were examined. Results indicate that as marital adjustment declines, evocative child effects on parenting increase, while the role of shared family experiences declines. However, the specific impact of marital adjustment on child-based genetic and child-specific nonshared environmental contributions to parenting differed for mothers and fathers. This study identifies a previously unexplored mechanism through which family subsystems influence each other.

IGEMS: the consortium on Interplay of Genes and Environment across Multiple Studies

The Interplay of Genes and Environment across Multiple Studies (IGEMS) group is a consortium of eight longitudinal twin studies established to explore the nature of social context effects and gene-environment interplay in late-life functioning. The resulting analysis of the combined data from over 17,500 participants aged 25-102 at baseline (including nearly 2,600 monogygotic and 4,300 dizygotic twin pairs and over 1,700 family members) aims to understand why early life adversity, and social factors such as isolation and loneliness, are associated with diverse outcomes including mortality, physical functioning (health, functional ability), and psychological functioning (well-being, cognition), particularly in later life.

The nature of nurture: disentangling passive genotype-environment correlation from family relationship influences on children's externalizing problems

The relationship between interparental conflict, hostile parenting, and children's externalizing problems is well established. Few studies, however, have examined the pattern of association underlying this constellation of family and child level variables while controlling for the possible confounding presence of passive genotype-environment correlation. Using the attributes of 2 genetically sensitive research designs, the present study examined associations among interparental conflict, parent-to-child hostility, and children's externalizing problems among genetically related and genetically unrelated mother-child and father-child groupings. Analyses were conducted separately by parent gender, thereby allowing examination of the relative role of the mother-child and father-child relationships on children's behavioral outcomes. Path analyses revealed that for both genetically related and genetically unrelated parents and children, indirect associations were apparent from interparental conflict to child externalizing problems through mother-to-child and father-to-child hostility. Associations between interparental conflict and parent-to-child hostility across genetically related and genetically unrelated parent-child groupings were significantly stronger for fathers compared to mothers. Results are discussed with respect to the role of passive genotype-environment correlation as a possible confounding influence in interpreting research findings from previous studies conducted in this area. Implications for intervention programs focusing on family process influences on child externalizing problems are also considered.

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

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

The Early Growth and Development Study: a prospective adoption study from birth through middle childhood

The Early Growth and Development Study is a prospective adoption study of birth parents, adoptive parents, and adopted children recruited in two cohorts (N = 561 triads). The primary study aims are to examine how family, peer, and contextual processes affect children's adjustment, and to examine their interplay (mediation, moderation) with genetic influences. Participants were recruited through adoption agencies located throughout the United States following the birth of a child. Assessments are ongoing, in 9-month intervals until the child reaches 3 years of age and in 1-year intervals thereafter through age 9. Data collection includes the following primary constructs: child temperament, social behavior, school performance, mental health, and health; birth and adoptive parent personality characteristics, mental health, competence, stress, health, context, substance use, parenting, and marital relations; and pregnancy use of drugs and maternal stress during pregnancy. DNA and salivary cortisol samples have also been collected. Analyses have indicated evidence for genotype-environment interactions during early childhood. Study procedures, sample representativeness (including tests of potential confounds in the adoption design), and an overview of findings to date are summarized, and future plans are described.

Intergenerational transmission of risk for social inhibition: the interplay between parental responsiveness and genetic influences

To better understand mechanisms underlying the intergenerational transmission of social anxiety, we used a prospective adoption design to examine the roles of genetic influences (inferred from birth mothers' social phobia) and rearing environment (adoptive mothers' and fathers' responsiveness) on the development of socially inhibited, anxious behaviors in children between 18 and 27 months of age. The sample consisted of 275 adoption-linked families, each including an adopted child, adoptive parents, and a birth mother. Results indicated that children whose birth mothers met criteria for the diagnosis of social phobia showed elevated levels of observed behavioral inhibition in a social situation at 27 months of age if their adoptive mothers provided less emotionally and verbally responsive rearing environments at 18 months of age. Conversely, in the context of higher levels of maternal responsiveness, children of birth mothers with a history of social phobia did not show elevated levels of behavioral inhibition. These findings on maternal responsiveness were replicated in a model predicting parent reports of child social anxiety. The findings are discussed in terms of gene-environment interactions in the intergenerational transmission of social anxiety.

Culture Moderates the Genetic and Environmental Etiologies of Parenting

A cultural behavior genetic approach was introduced as a prospective means to describe psychological differences between cultures. We compared genetic and environmental influences on remembered parenting for samples of twins from Japan and Sweden. Data were collected from 720 pairs of young adult Japanese twins and 824 pairs of adult Swedish twins using the Parental Bonding Instrument. In both samples, a very similar phenotypic factor structure was developed for maternal and paternal parenting. However, the genetic and environmental contributions were different. Parenting in Japan showed more genetic influences, whereas parenting in Sweden showed more shared environmental influences. Moreover, covariation among the six dimensions of parenting (i.e., maternal and paternal Warmth, Protectiveness, and Authoritarianism) was due to genetic correlations in Japan and to shared environmental correlations in Sweden. These results are consistent with the cultural psychology argument that parenting practices are child centered in Japan but parent centered in the West.

Effects of parental depressive symptoms on child adjustment moderated by hypothalamic pituitary adrenal activity: within- and between-family risk

Child hypothalamic pituitary adrenal (HPA) activity was investigated as a moderator of parental depressive symptom effects on child behavior in an adoption sample (n = 210 families). Adoptive parents' depressive symptoms and child internalizing and externalizing were assessed at 18, 27, and 54 months, and child morning and evening HPA activity measured through salivary cortisol at 54 months. Children's daily cortisol levels and day-to-day variability were tested as moderators of longitudinal associations between parent and child symptoms at within- and between-family levels. Mothers' symptoms related directly to child internalizing, but child evening cortisol moderated effects of fathers' symptoms on internalizing, and of both parents' symptoms on externalizing. Different paths of within-family risk dynamics versus between-family risk synergy were found for internalizing versus externalizing outcomes.

Current parental depression and offspring perceived self-competence: a quasi-experimental examination

A genetically-informed, quasi-experimental design was used to examine the genetic and environmental processes underlying associations between current parental depressive symptoms and offspring perceived self-competence. Participants, drawn from a population-based Swedish sample, were 852 twin pairs and their male (52 %) and female offspring aged 15.7 ± 2.4 years. Parental depressive symptoms were measured using the Center for Epidemiological Studies Depression scale. Offspring perceived self-competence was measured using a modified Harter Perceived Competence Scale. Cousin comparisons and Children of Twins designs suggested that associations between maternal depressive symptoms and offspring perceived self-competence were due to shared genetic/environmental liability. The mechanism responsible for father-offspring associations, however, was independent of genetic factors and of extended family environmental factors, supporting a causal inference. Thus, mothers and fathers may impact offspring perceived self-competence via different mechanisms and unmeasured genetic and environmental selection factors must be considered when studying the intergenerational transmission of cognitive vulnerabilities for depression.

Maternal self concept as a provider and cessation of substance use during pregnancy

OBJECTIVE

Maternal substance use during pregnancy is a common modifiable risk factor for poor birth outcomes, and is associated with long term psychological risks to offspring. As self concept is known to affect substance use behaviors in non-pregnant women, we hypothesized that self concept as a provider may be particularly salient to cessation of use during pregnancy. To isolate psychological processes specific to pregnancy from those associated with the transition to parenthood, we examined birth mothers who made adoption placements participating in the Early Growth and Development Study.

METHODS

We obtained lifetime and pregnancy substance use history and psychological measures at 3 to 4months postpartum from 693 women recruited from the Northwest, Southwest, and Mid-Atlantic regions of the United States. Life history calendar and computer-assisted personal interviewing methods were used to minimize reporting bias. Using logistic regression, we assessed the association of self concept as an adequate provider with cessation of substance use during pregnancy, controlling for sociodemographic variables, depressive symptoms experienced during pregnancy, past year antisocial behaviors, family history of substance abuse, timing of pregnancy recognition, timing of initiation of prenatal care, and emotional adjustment to the adoption decision.

RESULTS

More positive self-concept as an adequate provider was independently associated with cessation of substance use and earlier initiation of prenatal care during pregnancy [OR=1.223; 95% C.I. (1.005-1.489); B(SE)=.201(.100)]. Familial substance abuse, depressive symptoms, and antisocial behaviors during pregnancy, were also independent predictors, and more strongly associated with cessation [OR=.531; 95% C.I. (.375-.751); B(SE)=-.634 (.178)], [OR. 940; 95% C.I. (.906-.975); B(SE)=-.062 (.019)], [OR=.961; 95% C.I. (.927-.996); B(SE)=-.040 (.018)].

CONCLUSIONS

Enhancing maternal identity as a provider for the fetus during pregnancy, along with treatment of depression, may improve motivation to stop substance use.

Marital hostility and child sleep problems: direct and indirect associations via hostile parenting

The current study examined two family process predictors of parent-reported child sleep problems at 4.5 years in an adoption sample: marital hostility and hostile parenting. Participants were 361 linked triads of birth parents, adoptive parents, and adopted children. We examined direct and indirect pathways from marital hostility to child sleep problems via hostile parenting. Mothers' marital hostility at 9 months was associated with child sleep problems at 4.5 years. Fathers' marital hostility at 9 months evidenced an indirect effect on child sleep problems at 4.5 years via fathers' hostile parenting at 27 months. Findings were significant even after controlling for genetic influences on child sleep (i.e., birth parent internalizing disorders). The findings suggest targets for prevention and intervention programs that are potentially modifiable (e.g., hostile parenting, marital hostility), and inform theory by demonstrating that relations among marital hostility, hostile parenting, and child sleep problems are significant after accounting for genetic influences.

Effects of prenatal and postnatal parent depressive symptoms on adopted child HPA regulation: independent and moderated influences

This study used a prospective adoption design to investigate effects of prenatal and postnatal parent depressive symptom exposure on child hypothalamic-pituitary-adrenal (HPA) activity and associated internalizing symptoms. Birth mother prenatal symptoms and adoptive mother/father postnatal (9-month, 27-month) symptoms were assessed with the Beck Depression Inventory in a sample of 192 families as part of the Early Growth and Development adoption Study. Child morning/evening cortisol levels and child symptoms of internalizing disorders (according to mother/father report on the Child Behavior Checklist) were assessed at 54 months, and birth mother diurnal cortisol was measured at 48 months postnatal. Hierarchical linear modeling was used to test main effects and interactions of parents' symptoms predicting child cortisol, controlling for birth mother cortisol. Prenatal exposure to birth mother symptoms predicted lower child cortisol (main effect), as did postnatal exposure to adoptive parent symptoms (interaction effects). Adoptive mother 9-month symptoms exacerbated cortisol-lowering effects of both concurrent paternal symptoms and later (27-month) maternal symptoms, and the effect of birth mother cortisol. Lower child cortisol, in turn, was associated with higher child internalizing symptoms. Implications are discussed with respect to the intergenerational transmission of depression risk.

Higher-order structure in the trajectories of depression and anxiety following sudden involuntary unemployment

Recent work on comorbidity finds evidence for hierarchical structure of mood and anxiety disorders and symptoms. This study tests whether a higher-order internalizing factor accounts for variation in depression and anxiety symptom severity and change over time in a sample experiencing a period of major life stress. Data on symptoms of depression, chronic worry, and social anxiety were collected five times across seven months from 426 individuals who had recently lost jobs. Growth models for each type of symptom found significant variation in individual trajectories. Slopes were highly correlated across symptom type, as were intercepts. Multilevel confirmatory factor analyses found evidence for a higher-order internalizing factor for both slopes and intercepts, reflective of comorbidity of depression and anxiety, with the internalizing factor accounting for 54% to 91% of the variance in slopes and intercepts of specific symptom sets, providing evidence for both a general common factor and domain-specific factors characterizing level and change in symptoms. Loadings on the higher order factors differed modestly for men and women, and when comparing African American and White participants, but did not differ by age, education, or history of depression. More distal factors including gender and history of depression were strongly associated with internalizing in the early weeks after job loss, but rates of change in internalizing were associated most strongly with reemployment. Findings suggest that stressors may contribute in different ways to the common internalizing factor as compared to variance in anxiety and depression that is independent of that factor.

Genetic and environmental influences on the association between pubertal maturation and internalizing symptoms

The literature consistently shows an association between pubertal maturation and internalizing problems in girls. The association for boys is less clear. The present study examines genetic and environmental influences on the association between pubertal maturation and internalizing problems for boys and girls in two primarily Caucasian adolescent twin/sibling studies: The Swedish Twin study of CHild and Adolescent Development (706 same-sex twin pairs aged 13-14, M = 13.7 years, 50 % female), and the Nonshared Environment in Adolescent Development sample (US-based, 687 same-sex twin/sibling pairs aged 10-18, M = 13.6 years, 47 % female). For girls, more advanced pubertal maturation was associated modestly with more internalizing problems, and that association was entirely explained by shared environmental influences. For boys, the association between pubertal maturation and internalizing problems was weak and inconsistent. Results for girls were remarkably consistent across samples. Findings suggest that nongenetic mechanisms mediate the association between pubertal maturation and internalizing problems. Findings have implications for intervention such that environmental influences shared by twins/siblings may provide the best targets for intervention strategies designed to minimize the potential negative effects of pubertal maturation on internalizing symptoms in girls.

Fathering and mothering in the family system: linking marital hostility and aggression in adopted toddlers

BACKGROUND

  Previous studies have linked marital conflict, parenting, and externalizing problems in early childhood. However, these studies have not examined whether genes account for these links nor have they examined whether contextual factors such as parental personality or financial distress might account for links between marital conflict and parenting. We used an adoption design to allow for a clear examination of environmental impact rather than shared genes of parents and children, and assessments of parental personality and financial strain to assess the effects of context on relationships between marriage and parenting of both mothers and fathers.

METHOD

  Participants were 308 adoption-linked families comprised of an adopted child, her/his biological mother (BM), adoptive mother (AM) and adoptive father (AF). BMs were assessed 3-6 and 18 months postpartum and adoptive families were assessed when the child was 18 and 27 months old. Structural equations models were used to examine associations between marital hostility, fathers' and mothers' parenting hostility, and child aggressive behavior at 27 months of age. In addition, the contribution of financial strain and adoptive parent personality traits was examined to determine the associations with the spillover of marital hostility to hostile parenting.

RESULTS

  A hostile marital relationship was significantly associated with hostile parenting in fathers and mothers, which were associated with aggressive behavior in toddlers. Subjective financial strain was uniquely associated with marital hostility and child aggression. Antisocial personality traits were related to a more hostile/conflicted marital relationship and to hostile parenting.

CONCLUSIONS

  Results clarify mechanisms that may account for the success of early parent-child prevention programs that include a focus on parental economic strain and personality in addition to parent training.

Variation in the oxytocin receptor gene is associated with pair-bonding and social behavior

BACKGROUND

In specific vole and primate species the neuropeptide oxytocin plays a central role in the regulation of pair-bonding behavior. Here we investigate the extent to which genetic variants in the oxytocin receptor gene (OXTR) are associated with pair-bonding and related social behaviors in humans.

METHODS

We first genotyped twelve single nucleotide polymorphisms (SNPs) in the TOSS (Twin and Offspring Study in Sweden) (n = 2309) and the TCHAD (Swedish Twin Study of Child and Adolescent Development) (n = 1240), comprising measures of self-reported pair-bonding behavior. In the TOSS sample we further investigated one of the SNPs for measures of marital status and quality. Moreover, in the TCHAD sample we explored the longitudinal relationship between precursors of pair-bonding during childhood and subsequent behavior in romantic relationships. Finally, in the TCHAD study and in the Child and Adolescent Twin Study of Sweden (CATSS) (n = 1771), the association between the same SNP and childhood behaviors was investigated.

RESULTS

One SNP (rs7632287) in OXTR was associated with traits reflecting pair-bonding in women in the TOSS and TCHAD samples. In girls the rs7632287 SNP was further associated with childhood social problems, which longitudinally predicted pair-bonding behavior in the TCHAD sample. This association was replicated in the CATSS sample in which an association between the same SNP and social interaction deficit symptoms from the autism spectrum was detected.

CONCLUSION

These results suggest an association between variation in OXTR and human pair-bonding and other social behaviors, possibly indicating that the well-described influence of oxytocin on affiliative behavior in voles could also be of importance for humans.