Genetic questions for environmental studies. Differential parenting and psychopathology in adolescence.

BACKGROUND: Recent genetic evidence suggests that the most important environmental influences on normal and pathologic development are those that are not shared by siblings in the same family. We sought to determine the relationship between differences in parenting styles and depressive symptoms and antisocial behavior in adolescence, and to compare the influence of these nonshared experiences with genetic influences. METHODS: We studied 708 families with at least two same-sexed adolescent siblings who were monozygotic twins (93 families), dizygotic twins (99 families), ordinary siblings (95 families), full siblings in step families (181 families), half siblings in step families (110 families), and genetically unrelated siblings in step families (130 families). Data on parenting style were collected by questionnaire and by video recording of interaction between parents and children. RESULTS: Almost 60% of variance in adolescent antisocial behavior and 37% of variance in depressive symptoms could be accounted for by conflictual and negative parental behavior directed specifically at the adolescent. In contrast, when a parent directed harsh, aggressive, explosive, and inconsistent parenting toward the sibling, we found less psychopathologic outcome in the adolescent. CONCLUSIONS: Parenting behavior directed specifically at each child in the family is a major correlate of symptoms in adolescents. Furthermore, harsh parental behavior directed at a sibling may have protective effects for adolescents, a phenomenon we call the "siblin barricade."

Genetics and psychiatry: an unheralded window on the environment.

Two recent reviews in the American Journal of Psychiatry and the British Journal of Psychiatry reported on progress in understanding the genetics of psychiatric disorder. Both reviews focused on this progress as a prelude to psychiatric diagnostics and therapeutics based on molecular biology. Neither review recognized that the latest data in behavioral genetics support environmental causes for abnormal development and psychopathology as much as they support genetic causes. Moreover, these genetic data point clearly to a type of environmental cause with central importance: the environment that is specific or unique to each sibling in a family.

Co-occurrence of depressive symptoms and antisocial behavior in adolescence: a common genetic liability.

Recent reviews of research on child and adolescent psychopathology have highlighted the consistently high rates of co-occurring dimensions of psychopathology, particularly between internalizing and externalizing disorders, and have suggested that further research examining the causes of co-occurring syndromes is needed. The authors examined this question in a national sample of 720 same-sex adolescent siblings between 10 and 18 years of age consisting of monozygotic and dizygotic twins, full siblings, half siblings, and unrelated siblings. Composite measures of adolescent and parent reports and observational measures of depressive symptoms and antisocial behavior were subjected to behavioral genetic models that examine the genetic and environmental influences on individual differences in each dimension as well as in the co-occurrence between dimensions. Results indicated that approximately half of the variability in depressive symptoms and antisocial behavior is attributed to genetic factors; shared and nonshared environmental influences were also significant. The co-occurrence of depressive and antisocial symptoms was explained by genetic and shared and nonshared environmental influences. Specifically, approximately 45% of the observed covariation between depressive and antisocial symptoms could be explained by a common genetic liability. Results are interpreted in light of contribution of genetic studies to debates on child and adolescent psychopathology.

Parent ratings of EAS temperaments in twins, full siblings, half siblings, and step siblings.

A twin/family design was used to explore genetic contributions to personality; to evaluate whether twins and nontwins yield different genetic results; and to test for the presence of contrast effects, the tendency of a rater to contrast one sibling with the other, thereby magnifying existing behavioral differences. The sample consisted of 708 adolescent same-sex sibling pairs from 10 to 18 years of age. Pairs included identical (monozygotic; MZ) and fraternal (dizygotic; DZ) twins, and full siblings in nondivorced families; and full, half, and unrelated siblings in stepfamilies. Mothers and fathers rated the temperament of their children on the EAS Temperament Survey (A. H. Buss & R. Plomin, 1984). Model-fitting analyses revealed significant genetic influences on each of the four EAS dimensions; however, for some dimensions, heritability estimates were significantly greater for twins than for nontwins. Overall, the data were best described by a sibling interaction model, which indicated significant contrast effects.

What matters? What does not? Five perspectives on the association between marital transitions and children's adjustment.

This article presents an analysis of 5 views of factors that contribute to the adjustment of children in divorced families or stepfamilies. These perspectives are those that emphasize (a) individual vulnerability and risk; (b) family composition; (c) stress, including socioeconomic disadvantage; (d) parental distress; and (e) disrupted family process. It is concluded that all of these factors contribute to children's adjustment in divorced and remarried families and that a transactional model examining multiple trajectories of interacting risk and protective factors is the most fruitful in predicting the well-being of children.

Marital transitions. A child's perspective.

Despite a recent leveling off of the divorce rate, almost half of the children born in the last decade will experience the divorce of their parents, and most of these children will also experience the remarriage of their parents. Most children initially experience their parents' marital rearrangements as stressful; however, children's responses to their parents marital transitions are diverse. Whereas some exhibit remarkable resiliency and in the long term may actually be enhanced by coping with these transitions, others suffer sustained developmental delays or disruptions. Others appear to adapt well in the early stages of family reorganizations but show delayed effects that emerge at a later time, especially in adolescence. The long-term effects are related more to the child's developmental status, sex, and temperament; the qualities of the home and parenting environments; and to the resources and support systems available to the parents and child than they are to divorce or remarriage per se. In recent years, researchers have begun to move away from the view that single-parent and remarried families are atypical or pathogenic families and are focusing on the diversity of children's responses and to the factors that facilitate or disrupt the development and adjustment of children experiencing their parents' marital transitions.

Contemporary research on parenting. The case for nature and nurture.

Current findings on parental influences provide more sophisticated and less deterministic explanations than did earlier theory and research on parenting. Contemporary research approaches include (a) behavior-genetic designs, augmented with direct measures of potential environmental influences; (b) studies distinguishing among children with different genetically influenced predispositions in terms of their responses to different environmental conditions; (c) experimental and quasi-experimental studies of change in children's behavior as a result of their exposure to parents' behavior, after controlling for children's initial characteristics; and (d) research on interactions between parenting and nonfamilial environmental influences and contexts, illustrating contemporary concern with influences beyond the parent-child dyad. These approaches indicate that parental influences on child development are neither as unambiguous as earlier researchers suggested nor as insubstantial as current critics claim.

Adolescent perceptions as mediators of parenting: genetic and environmental contributions.

Explaining how genetic factors contribute to associations between parenting and adolescent adjustment is an important next step in developmental research. This study examined the mediating effect of adolescent perceptions on these associations and the genetic and environmental influences underpinning the mediated relationship. Parent, adolescent, and observer ratings of parenting and adolescent adjustment were used in a genetically informative sample of 720 same-sex sibling pairs from 10 to 18 years old. Adolescent perceptions of parenting did significantly mediate a composite measure of parental conflict-negativity and adolescent antisocial behavior and depressive symptoms. The most substantial genetic contributions to the association between parenting and adolescent maladjustment were those mediated by adolescent perceptions. Once genetic and environmental contributions to adolescent perceptions of parenting were removed, shared environmental factors became more important for the remaining direct association.

Relationships between parenting and adolescent adjustment over time: genetic and environmental contributions.

The predictive association between parenting and adolescent adjustment has been assumed to be environmental; however, genetic and environmental contributions have not been examined. This article represents one effort to examine these associations in which a genetically informative design was used. Participants were 395 families with adolescent siblings who participated in the Nonshared Environment in Adolescent Development (D. Reiss et al., 1994) project at 2 times of assessment, 3 years apart. There were 5 sibling types in 2 types of families: 63 identical twins, 75 fraternal twins, and 58 full siblings in nondivorced families and 95 full, 60 half, and 44 genetically unrelated siblings in stepfamilies. Results indicate that the cross-lagged associations between parental conflict-negativity and adolescent antisocial behavior and depressive symptoms can be explained primarily by genetic factors. These findings emphasize the need to recognize and examine the impact that adolescents have on parenting and the contribution of genetic factors to developmental change.

Adolescents' relationships to siblings and mothers: a multivariate genetic analysis.

Research has consistently demonstrated that children's behavior toward their siblings tends to resemble interactions occurring in the parent-child relationship. This study examined the relative contributions of genetic and environmental influences to the covariation between sibling relationships and mother-adolescent relationships. Reported and observed family interactions were assessed for 719 same-sex sibling pairs of varying degrees of genetic relatedness. The covariance between mother-adolescent and sibling interactions was decomposed into genetic, shared, and nonshared environmental components. The overlapping effects of shared environment on the two relationship subsystems explained most of the covariance. Smaller but significant genetic and nonshared environmental effects were also found. The consistency of these findings with family processes, such as modeling, is discussed.

The importance of shared environmental influences in explaining the overlap between mother's parenting and sibling relationships: reply to Neale (1999)

This article addresses concerns raised by M. C. Neale (1999) in his commentary on the D. A. Bussell et al. (1999) Nonshared Environment in Adolescent Development (NEAD) study. These concerns fall into two categories: (a) model assumptions and sample design and (b) testing of alternative models. The validity of the assumptions of quantitative genetic models is a concern for all researchers in this area. Discussion of those assumptions in this reply is brief and focuses on those most relevant to the NEAD sample. The two alternative models proposed by Neale were designed to provide alternatives to the large shared environmental effect found in the original report of Bussell et al. Because these alternative models did not provide a better fit, the appropriateness of Bussell et al.'s basic model and the importance of shared environmental influences for explaining the association among family subsystems are supported.

Differential parenting as a within-family variable.

Nonshared environmental influences have been found to be important for adolescent development. This study of 516 families investigated whether differential parental negativity or warmth is linked to adolescent adjustment apart from the effect of the level of parenting toward each child separately. After accounting for level of parental treatment to the adolescent, the authors found that differential parenting to the siblings contributed unique variance in adjustment. Significant interactions were found between level of parenting and differential parenting. In each case, differential parenting was more strongly linked to adjustment when the level of parenting was low in warmth or high in negativity. These results are indirect evidence that differential parenting can be considered a within-family influence on sibling adjustment and as direct evidence that nonshared environmental factors may systematically vary in strength between families.

Relationship between perceptual differences of parenting and adolescent antisocial behavior and depressive symptoms.

The relation between adolescent negative adjustment and differences in parent-child ratings of parents' warmth and negativity was examined with a national sample of 720 families. It was predicted that perceptual differences (PDs) would be linked to more negative adjustment. Adjustment was regressed on PDs, which were calculated as absolute differences between parent and child ratings of parenting. Results showed that PDs were significantly associated with adjustment independent of the level of parenting behavior. Associations differed by gender for PDs over maternal verbal aggression. Some of the most important results were curvilinear effects indicating that both high and low, but not medium, levels of PDs are linked with maladjustment. Finally, differences between younger and older adolescents were found: The linear relationship between PDs over parental negativity and maladjustment disappeared for older adolescents.

Coping with family transitions: winners, losers, and survivors.

This article presents the results of a longitudinal study of the effects of divorce and remarriage on children's adjustment. It was found that individual characteristics, such as children's temperament, family relations, and extrafamilial factors, played an important role in exacerbating or buffering children from negative consequences associated with their parents' marital transitions. Although boys in divorced families and children in remarried families showed more problems in adjustment than did children in nondivorced families, some also showed remarkable resiliency in the face of multiple life stressors.

Sibling differentiation in adolescence: implications for behavioral genetic theory.

The presence of sibling "differentiating processes"--defined as processes in which increased sibling similarity in environmental or genetic factors leads to differences in sibling outcomes-poses a challenge for standard behavioral genetic theory and research. The presence of differentiation processes may affect estimates of genetic and environmental parameters in ways that have not been fully recognized. Utilizing data from the Nonshared Environment and Adolescent Development project, this study examined whether differentiating processes existed for seven composite indices of positive and negative adolescent adjustment. The 720 sibling pairs in the study were broken down into groups by age difference (0-4 years) between siblings. The hypothesis that siblings close in age would demonstrate lower correlations on adjustment measures was generally supported at two time points, three years apart. However, siblings one year apart at Time 1 were more similar to each other than were siblings two years apart, suggesting that shared environmental influences counteract sibling differentiation processes for these siblings. The overall trend supporting sibling differentiation was found to be unrelated to measures of sibling positivity and negativity.