Nonshared environmental influences on individual differences in early behavioral development: a monozygotic twin differences study

The monozygotic (MZ) twin differences method was used to investigate nonshared environmental (NSE) influences independent of genetics. Four-year-old MZ twin pairs (N = 2,353) were assessed by their parents on 2 parenting measures (harsh parental discipline and negative parental feelings) and 4 behavioral measures (anxiety, prosocial behavior, hyperactivity, and conduct problems). Within-pair differences in parenting correlated significantly with MZ differences in behavior, with an average effect size of 3%. For the extreme 10% of the parenting-discordant and behavior-discordant distributions, the average NSE effect size was substantially greater (11%), suggesting a stronger NSE relationship for more discordant twins. NSE relationships were also stronger in higher risk environments, that is, families with lower socioeconomic status, greater family chaos, or greater maternal depression.     

A monozygotic twin difference study of friends' aggression and children's adjustment problems

This study used the monozygotic (MZ) twin difference method to examine whether differences in friends' aggression increased the differences in MZ twins' aggression and depressive symptoms from kindergarten to Grade 1 and whether perceived victimization by the friend played a mediating role in this context. Participants were 223 MZ twin pairs. Results showed that differences in kindergarten friends' aggression significantly predicted an increased difference in MZ twins' aggression from kindergarten (mean age = 6.7 years) to Grade 1 (mean age = 7.5 years) for both boys and girls. Differences in perceived victimization by the friend mediated this association, albeit only in boys. Differences in perceived victimization by the friend also predicted an increase in MZ twins' differences in depressive symptoms. These results support the importance of friendship experiences during early childhood.     

The limits of genetic influence: a behavior-genetic analysis of infant-caregiver relationship quality and temperament

This report presents data on 9-month-old twin pairs (n(MZ)=172; n(DZ)=333) from the Early Childhood Longitudinal Study, demonstrating that the role of genetic variation among infants is trivial and the shared and nonshared environment is substantial in accounting for the observed quality of infant-caregiver relationships. In contrast, maternal reports of temperament were best accounted for by genetic variation and nonshared environmental influences. Interestingly, however, shared environmental effects were documented for observations of temperament. Consistent with a growing database, the current study calls into question the ubiquity of heritability effects in all domains of psychological inquiry. It also bolsters consensus in the field of developmental psychology that shared environmental effects are not as elusive as had once been thought.     

Genetic and Environmental Influences on Negative Life Events From Late Childhood to Adolescence

This multiwave longitudinal study tested two quantitative genetic developmental models to examine genetic and environmental influences on exposure to negative dependent and independent life events. Participants (N = 457 twin pairs) completed measures of life events annually from ages 9 to 16. The same genetic factors influenced exposure to dependent events across time and increased in magnitude during the transition to adolescence. Independent events were less genetically influenced than dependent events in boys, but not girls. Shared environmental influences decreased in magnitude as youth transitioned into adolescence. Nonshared environmental influences were mostly age specific and contributed significantly to both types of events at all ages. Results provide theoretical implications for developmental risk pathways to stress exposure and stress‐related psychopathology.     

Why are hyperactivity and academic achievement related?

Although a negative association between hyperactivity and academic achievement is well documented, little is known about the genetic and/or environmental mechanisms responsible for the association. The present study explored links between parent and teacher ratings of hyperactive behavior problems and teacher-assessed achievement in a sample of 1,876 twin pairs (mean age 7.04 years). The results did not differ across rater, nor were there significant differences between males or females or for twins in the same or different classrooms. Hyperactivity was significantly correlated with achievement. Multivariate model-fitting analyses revealed significant genetic and nonshared environmental covariance between the two phenotypes. In addition, bivariate heritabilities were substantial, indicating that the phenotypic correlations between hyperactivity and achievement were largely mediated by genetic influences.     

Parenting and child behavioral adjustment in early childhood: a quantitative genetic approach to studying family processes

The aim of this study was to examine environmental and gene-environment processes linking parenting (i.e., affect, control, responsiveness) and preschool children's behavioral adjustment difficulties (e.g., noncompliance, conduct problems) by using bivariate genetic analyses of parents' and observers' ratings. The sample included 120 identical and same-sex fraternal twin pairs (M age = 43 months). Data sources included in-home observations, interviews, and parents' reports. Observers' ratings of children's difficult behaviors included shared and nonshared environmental variance. In contrast, parents' ratings of children's conduct problems showed genetic and nonshared environmental variance. Observer-rated maternal behavior included shared and nonshared environmental variance, although maternal responsiveness also included child genetic variance. Parent self-reported negative and positive affect included shared and nonshared environment as well as child genetic variance. There was no evidence for gene-environment interaction or dominance. Higher levels of difficult behavior and conduct problems covaried with higher levels of maternal negative affect and control and lower levels of maternal positive affect and control. Shared environmental mediation of these correlations was found for observations, whereas genetic and nonshared environmental mediation was found for parents' ratings. In general, estimates of shared environmental variance and mediation were greatest for observational data, and estimates of child genetic variance and mediation were greatest for parent-rated data. The implications of this pattern of findings for genetic research on family processes are discussed.     

A Twin Study of Attachment in Preschool Children

The degree to which individual differences in child-parent attachment were mediated by genetic, shared environmental, and nonshared environmental influences was investigated. One hundred and ten preschool-aged twin pairs (N = 220) were assessed in the Strange Situation and coded using conventional four-way classifications and a continuous measure of attachment security. The degree of sibling similarity in attachment was substantial, with an overall concordance rate of 67% at the secure/insecure level. The degree of concordance was equally high in monozygotic and dizygotic twin pairs, 70% and 64%, respectively, suggesting little genetic influence but a moderate degree of discordance. Twin similarity on the continuous measure of attachment security was r(57) = .48 and r(53) = .38 for monozygotic and dizygotic twin pairs, respectively, also consistent with a modest role for genetic influence but a significant effect for shared and nonshared environment. The implications for genetic influences on the environment and for understanding nonshared and shared environmental influences are discussed.     

Childhood maltreatment,psychological resources,and depressive symptoms in women with breast cancer

Childhood maltreatment is associated with elevated risk for depression across the human lifespan. Identifying the pathways through which childhood maltreatment relates to depressive symptoms may elucidate intervention targets that have the potential to reduce the lifelong negative health sequelae of maltreatment exposure. In this cross-sectional study, 271 women with early-stage breast cancer were assessed after their diagnosis but before the start of adjuvant treatment (chemotherapy, radiation, endocrine therapy). Participants completed measures of childhood maltreatment exposure, psychological resources (optimism, mastery, self-esteem, mindfulness), and depressive symptoms. Using multiple mediation analyses, we examined which psychological resources uniquely mediated the relationship between childhood maltreatment and depressive symptoms. Exposure to maltreatment during childhood was robustly associated with lower psychological resources and elevated depressive symptoms. Further, lower optimism and mindfulness mediated the association between childhood maltreatment and elevated depressive symptoms. These results support existing theory that childhood maltreatment is associated with lower psychological resources, which partially explains elevated depressive symptoms in a sample of women facing breast cancer diagnosis and treatment. These findings warrant replication in populations facing other major life events and highlight the need for additional studies examining childhood maltreatment as a moderator of treatment outcomes.     

The association of childhood sexual abuse with depressive symptoms during pregnancy, and selected pregnancy outcomes.

OBJECTIVES: The objectives were: (1) to investigate the association during pregnancy of sexual abuse before the age of 18 on depressive symptomatology in pregnancy, controlling for the presence of negative life events and challenges; and (2) to investigate the association of selected pregnancy outcomes (maternal labor and delivery factors, infant birth weight and gestational age) with sexual abuse before age 18. METHODS: Three hundred fifty-seven primiparous women aged 18 years and older were interviewed between 28-32 weeks gestation with reference to current functioning and past history (Objective 1). Medical record information was abstracted after delivery for pregnancy, labor and delivery factors, and pregnancy outcomes (Objective 2). RESULTS: Thirty-seven percent of the women reported past sexual abuse. Prevalence was not associated with ethnic background, educational level, or hospital payment source. Previously sexually-abused pregnant women reported significantly higher levels of depressive symptomatology, negative life events, and physical and verbal abuse before and during pregnancy. There were no significant associations found between past sexual abuse and labor or delivery variables or newborn outcomes. CONCLUSIONS: Previously sexually-abused pregnant women reported a wider constellation of past and current functioning problems than nonabused women although past sexual abuse was not associated with pregnancy outcome. Prenatal care provides a unique opportunity to evaluate the impact of life history and current life events during pregnancy, and to develop a coordinated intervention plan.     

The relationship between sexual abuse during childhood and parenting outcomes: modeling direct and indirect pathways

OBJECTIVE: This study examined the association between childhood sexual abuse (CSA) and parenting outcomes including parenting stress, feelings of competence and discipline strategies. Maternal depression and current partner violence were hypothesized to be mediators of the association between CSA and parenting. METHOD: This study is based on secondary data analysis of archived data. The participants were 263 primiparous mothers (107 with a history of CSA and 156 comparison mothers recruited from a prenatal clinic prior to the birth of their first child. Mothers were interviewed twice: once when they were between 28 and 32 weeks gestation and again when their child was between 2 and 4 years of age. During the first interview, women were asked about childhood experiences of sexual abuse. During their second interview, they were asked about current symptoms of pathology and experiences with partner violence and parenting beliefs and practices. RESULTS: Structural Equation Modeling indicated that the relationship between CSA and punitive discipline was mediated by maternal depression and current partner violence. CSA was associated with higher maternal depression and higher partner violence. CSA, maternal depression, and current partner violence were associated with more negative parental perceptions and higher punitive discipline. Once maternal depression and current partner violence were in the model, the relationship between CSA and parenting outcomes was no different from zero. CONCLUSION: These results highlight the risks associated with CSA for parenting outcomes and suggest two potential pathways for this increased risk.     

Genetic and environmental influences in adolescent peer socialization: evidence from two genetically sensitive designs

Harris argues that peer relationships are the chief determinants of personality development. Harris's thesis makes the behavioral genetic investigation of peer groups particularly timely. The present study examined genetic and environmental contribution to self-reported peer-group characteristics in two samples of adolescent siblings: 180 adoptive and nonadoptive sibling pairs from the Colorado Adoption Project, and 386 sibling pairs from the Nonshared Environment and Adolescent Development Study. Substantial genetic influence emerged for college orientation, with the remaining variance accounted for by nonshared environment. For delinquency, however, the majority of the variance was explained by nonshared environment. Although genetic influence was implicated for peer popularity in twin analyses, genetic factors were not important in explaining individual differences in nontwin siblings. These results suggest that although some dimensions of peers are somewhat mediated by genetic factors, nonshared environmental influence is substantial.     

A genetically sensitive investigation of the effects of the school environment and socio‐economic status on academic achievement in seven‐year‐olds

Although it is well established that school characteristics (SCH) and socio‐economic status (SES) are associated with academic achievement (ACH), these correlations are not necessarily causal. Because academic achievement shows substantial genetic influence, it is useful to embed such investigations in genetically sensitive designs in order to examine environmental influences more precisely by controlling genetic influence on ACH. In the first study of this kind for academic achievement, data were collected for 1,063 same‐sex pairs of seven‐year‐old MZ and DZ twins for teacher‐assessed ACH, UK statistics on SCH, and parent‐reported SES. Exclusive of genetic influence on school achievement, shared environment (environmental influences that make siblings similar) accounts for 12% of the variance in academic achievement. SCH accounts for 17% and SES accounts for 83% of this shared environmental variance. Exclusive of genetic and shared environmental influence including SCH and SES, nonshared environment (environmental influences that do not make siblings similar) accounts for 19% of the variance in academic achievement. The importance of nonshared environmental influences on academic achievement leads to the question of what these child‐specific experiences might be that are not shared by children in the same family, school, and classroom.     

Child maltreatment and adult depressive symptoms: Roles of self-compassion and gratitude

Child maltreatment, including abuse (physical, emotional, and sexual) and neglect (physical and emotional), is positively associated with depressive symptoms in adulthood. However, most studies have been conducted within a psychopathological framework and focused on underlying dysfunctional processes (e.g., insecure attachment styles, maladaptive schemas, and negative attribution styles). Protective factors that affect the relationship between child maltreatment and adult depressive symptoms are underexplored. Guided by emotion regulation theory and the perspective of positive psychology, we examined the roles of self-compassion and gratitude as protective factors in the relationship between child maltreatment and adult depressive symptoms in a sample of 358 college students. Results showed that psychological maltreatment (emotional abuse and emotional neglect) was associated with adult depressive symptoms through decreased self-compassion. Neglect (emotional neglect and physical neglect) and sexual abuse were associated with adult depressive symptoms through decreased gratitude. There was no association between physical abuse and depressive symptoms through either self-compassion or gratitude. Our findings suggest that clinical practices focusing on self-compassion and gratitude might help prevent the development of adult depressive symptoms among clients with a history of maltreatment in childhood.     

Genetic and environmental influences on rapid naming and reading ability: A twin study

The present study assesses the genetic and environmental etiologies of reading, rapid naming (RN), and their covariation by fitting multivariate structural equation models to data from 587 twin pairs in which at least one member of the pair exhibited reading difficulties (low-range) and from 360 control (normal-range) twin pairs who were tested in the Colorado Learning Disabilities Research Center. Results from a bivariate phenotypic analysis with two hypothesized latent factors, READ and RN, indicated that the correlation between reading and rapid naming performance for the low-range sample was significantly higher than that of the normal-range sample. When this model was partitioned to include estimates of genetic, shared environmental, and nonshared environmental influences, resulting heritability estimates did not differ significantly for the low-range and normal-range samples for either READ or RN. However, similar to the phenotypic correlation, the genetic correlation between the READ and RN latent factors could not be equated for the two groups. Thus, the etiology of the relationship between reading performance and rapid naming may differ for children with reading difficulties and normally-achieving readers. Moreover, these results support previous findings that the best predictors of reading skills may differ for samples of children with normal reading levels and those with reading difficulties.     

Maternal negative emotional expression and discipline in Beijing,China: The moderating role of educational attainment

The current study shows that parental punitive discipline places children at risk of developing internalizing and externalizing problems. Although some studies have analyzed the reasons for the use of discipline methods, little to no research has analyzed the moderating effects. In this study, we examine the relationship between maternal negative emotional expression and mothers’ use of disciplinary methods (psychological aggression, corporal punishment and physical maltreatment) and the moderating effects of educational attainment in Chinese societies. Five hundred and sixteen mothers with preschool-aged children were recruited to participate in this research. The Chinese versions of the Self-Expressiveness in the Family Questionnaire (SEFQ) and the Parent-Child Conflict Tactics Scales (CTSPC) were used to measure the mothers’ negative emotional expression and discipline, respectively. The results suggested that the mothers’ negative emotional expression was positively related to their disciplinary behaviors. Moreover, maternal educational attainment moderated the association between negative emotional expression and discipline. The findings of the current study highlight the importance of considering how mothers’ educational backgrounds may interact with their emotions to influence maternal disciplinary behaviors.     

Interplay between childhood maltreatment, parental bonding, and gender effects: impact on quality of life

OBJECTIVE: The aim of this study was to examine associations between childhood adversity, parental bonding, gender, depressive symptoms, and quality of life in non-treatment-seeking adults from the community. METHOD: Effects of differential parental rearing were compared in adults who reported a high degree of childhood maltreatment (n=72) and those who reported no significant adverse events in childhood (n=69). Subjects completed retrospective measures of childhood maltreatment and perceived parenting style, as well as measures of current depressive symptoms and quality of life. RESULTS: The subjects without childhood maltreatment were younger and endorsed less current depressive symptomatology than did subjects with childhood maltreatment. While the subjects without a history of maltreatment reported more "optimal" bonding experiences with their parents, the maltreatment group members were more likely to characterize their early parental bonding experiences in terms of "affectionless control" (p<.001 for both maternal and paternal parenting), "affectionate constraint" (p=.025 for maternal parenting and p=.004 for paternal parenting), or "weak or absent" bonding (p<.001 for both maternal and paternal parenting). Results of a multiple regression analysis revealed that overall quality of paternal care (p=.015) and current level of depressive symptoms (p<.001) were significant independent predictors of adult quality of life. Gender effects between subjects providing parental bonding data were limited to the group with childhood maltreatment. CONCLUSION: These findings extend previous work documenting a relationship between early life maltreatment and suboptimal parental bonding, suggesting gender-specific effects of maternal and paternal care. Effects of childhood maltreatment on quality of life in adulthood appear to be linked with the quality of childhood paternal care and the occurrence of depressive symptomatology in adulthood, suggesting possible targets for primary or secondary prevention.     

A biometrical analysis of perceptions of family environment: a study of twin and singleton sibling kinships

Biometrical genetic analysis was applied to sibling and twin kinship data on 2 dimensions of perceived home environment. Correlations on 1 dimension, Restrictiveness-Permissiveness, were equal and significant for all kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings significant for all 4 kinships: MZ twins, DZ twins, same-sex siblings, and opposite-sex siblings (r greater than .40). An E2-E1 biometrical model fitted Restrictiveness-Permissiveness, implying that treatments common to siblings create agreement about perceived environment. As intrapair differences were the same for all 4 kinships under this model, the equal environments assumption of the twin method was supported. In contrast, the Acceptance-Rejection dimension fitted a G-E1 model that makes the assumption that sibling similarity is the result of genetic factors and postulates an absence of shared environmental influences. This finding suggests that this aspect of home environment may depend as much on the child's inherited traits as on actual treatments and is in accord with the genetic analysis of individual traits in that developmentally effective environmental factors do not appear to be common to siblings.     

Genetic Influences on Activity Level in Early Childhood: Do Situations Matter?

Although genetic influences on individual differences in activity level (AL) are well documented, few studies have considered the etiology of AL from a contextual perspective. In the present study, cross-situational and context-specific genetic effects on individual differences in AL at age 2 were examined. The AL of 312 twin pairs (144 monozygotic and 168 dzygotic) was mechanically assessed with actigraphs in the home and in laboratory test and play situations. AL displayed significant genetic variance in all 3 situations. Moreover, actigraph scores significantly correlated across situations. Multivariate genetic model-fitting analyses found that the observed cross-situational continuity in AL was due entirely to genetic factors. Situational differences in AL arise from genetic, shared environmental, and nonshared environmental influences.     

A life course perspective of victimization,child welfare involvement,cumulative stress and mental health for mothers on probation and parole

Women involved in the criminal justice system experience multiple forms of adversity over their lifetimes. These events may include childhood abuse, involvement in the child welfare system as children, intimate partner violence victimization during adulthood, and punitive interactions with the child welfare system as mothers. Community supervision (e.g. probation or parole) entails particular stressors, such as obtaining basic needs and employment. A majority of women under community supervision also experience depression and anxiety. The current study used the Stress Process Model to investigate associations between childhood and adulthood stressors (including childhood abuse, intimate partner violence and child welfare system involvement), recent stressful life events, and symptoms of depression and anxiety for mothers (n = 348) on probation and parole. All of the mothers had experienced some form of childhood and/or adulthood victimization. Structural equation modeling was conducted to examine how childhood abuse, adulthood victimization, and child welfare system involvement as a child and a mother were associated with recent stressful life events and symptoms of depression and anxiety. Results indicated multiple direct and indirect relationships from childhood and adulthood stressors to mental health symptoms as women navigated probation and parole. For example, adverse childhood experiences were associated with elevated anxiety and depression symptoms via higher levels of recent stressful life events and adverse adulthood experiences. These findings highlight relationships between childhood abuse and adulthood factors and the mental health of mothers involved in the criminal justice system, with implications for theory, practice, and research.     

The Home Environment Shapes Emotional Eating

Emotional overeating (EOE) is the tendency to eat more in response to negative emotions; its etiology in early life is unknown. We established the relative genetic and environmental influences on EOE in toddlerhood and early childhood. Data were from Gemini, a population‐based cohort of 2,402 British twins born in 2007. EOE was measured using the “emotional overeating” scale of the Child Eating Behavior Questionnaire (CEBQ) at 16 months and 5 years. A longitudinal quantitative genetic model established that genetic influences on EOE were minimal; on the other hand, shared environmental influences explained most of the variance. EOE was moderately stable from 16 months to 5 years and continuing environmental factors shared by twin pairs at both ages explained the longitudinal association.