Beth Manke

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. Harriss 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.

Children’s Perceptions of Sibling Conflict During Middle Childhood: Issues and Sibling (Dis)similarity

This study focused on the content (rather than the frequency) of sibling conflict, conflict initiation, and conflict resolution during middle childhood. Sibling similarity and heritability of children’s perceptions of sibling conflict were also examined. One hundred and eight school-aged sibling pairs were interviewed using a semi-structured interview format (average ages were 11.1 years and 8.2 years, respectively). Children’s responses were coded using 16 categories extracted from the literature and interviews. Results showed that descriptions of disagreements revolved around issues between the siblings (e.g., sharing personal possessions and physical aggression) rather than parental favoritism. Parental intervention, on the other hand, was cited as the most common outcome. Children in the same family rarely mentioned the same issues and only six out of 16 of the topics showed a pattern suggesting heritability. The importance of the school-aged sibling relationship to children’s sense of self, personal rights, and social understanding is discussed.

Siblings in domestically violent families: experiences of interparent conflict and adjustment problems.

This research examines whether siblings in domestically violent families differ in experiences of interparent conflict and whether such differences are associated with differences in childrens adjustment. Participants included 112 sibling pairs and their mothers temporarily residing in domestic violence shelters. Children completed measures of their experiences of interparent conflict, and children and mothers reported on childrens adjustment problems. Cross-sibling correlations for experiences of interparent conflict were low to moderate. Sibling differences in threat appraisals of interparent conflict were associated with sibling differences in internalizing problems. Differences in self-blame appraisals were associated with differences in internalizing and externalizing problems. The direction of the relations indicated that the sibling who felt more threatened by or more at fault for interparent conflict experienced more adjustment problems. These findings suggest the potential utility of individually assessing sibling experiences of interparent conflict and tailoring interventions individually.

A Genetic Analysis of Differential Experiences of Adolescent Siblings Across Three Years

Environmental factors work to make siblings in the same family different from one another rather than similar. The Sibling Inventory of Differential Experience (SIDE; Daniels & Plomin, 1985) was constructed to evaluate how differently siblings perceive their experiences to be across three domains: parental treatment, sibling treatment, and peer characteristics. The goals of the study were threefold: to assess the degree to which siblings agree about their differential experiences; to examine the stability of perceived differential treatment across three years; and to assess genetic and environmental contributions to the SIDE using both the twin design and the stepfamUy design. These goals were explored using a genetically sensitive sample of 719 samesex sibling pairs ranging from 10 to 18 years of age of whom 94% of eligible pairs were retested three years later. Results indicated moderate agreement between siblings, and considerable stability across 3 years. As in previous research on the SIDE, MZ vs. DZ results indicated greater genetic influence than did results for full siblings vs. genetically unrelated siblings. The results suggest that, although intended as a measure of nonshared environment, the SIDE is not impervious to genetic influence as assessed by the twin design.

Adolescent Familial Interactions: A Genetic Extension of the Social Relations Model:

The purpose of the present paper was to investigate genetic and environmental contributions to significant child actor effects (i.e. a persons tendency to behave in a similar way to all family members), child partner effects (i.e. a persons tendency to elicit similar interactions from all family members), and sibling relationship effects (i.e. factors unique to the sibling dyadic relationship) identified in an application of the Social Relations Model (SRM: Kenny & La Voie, 1984) to familial interaction data. We examined familial warmth, conflict, and self-disclosure about both positive and negative things in 60 nonadoptive and 44 adoptive families with siblings aged 8-17 years. Our goals were to assess sibling resemblance and to disentangle resemblance due to genetic heritage from resemblance due to environmental experiences for SRM effects identified as significant. Genetic influence was found for actor effects for conflict and self-disclosure about positive things. In contrast, dyadic relationship effects for warmth and self-disclosure about both positive and negative things showed no significant genetic influence. Moderate shared environmental influences were found for both actor and sibling relationship effects. However, most of the environmental influences for both actor and sibling relationship effects were of the nonshared variety, suggesting that unique environmental experiences are important for childrens familial interactions.

Combining the Social Relations Model and Behavioral Genetics to Explore the Etiology of Familial Interactions

SUMMARY This review focuses on the Social Relations Model (SRM) and a genetic extension of this model as one approach for identifying the processes by which genetic factors influence familial exchanges (Kenny & La Voie, 1984). The basic SRM and its ability to decompose dyadic measures of family interaction into actor, partner and dyadic relationship effects is described followed by findings from 3 recent studies. Results indicate that much of familial interaction is in fact relationship specific, and not due to individual-level effects. We also discuss why and how the basic SRM is enriched through the incorporation of genetically sensitive designs and present results that suggest the importance of nonshared environmental contributions for both individual and dyadic level effects. Finally, directions for future family research are proposed including the use of genetically informative designs, the collection of round-robin robin data, and the incorporation of more diverse samples.

Predicting 4-Year Graduation: Using Social Cognitive Career Theory to Model the Impact of Prescriptive Advising, Unit Load, and Students’ Self-Efficacy

In this study, we investigated how environmental, cognitive, and demographic variables influenced students’ ability to graduate from a 4-year university in 4 years. Specifically, we examined how behaviors related to social cognitive career theory (i.e., self-efficacy, outcome expectations, and academic goals) were influenced by contextual experiences related to prescriptive academic advising to ultimately predict students’ ability to graduate in 4 years. After holding students’ demographic characteristics constant, results from structural regression analyses indicated that prescriptive advising had a direct effect on students’ 4-year graduation rates. In addition, prescriptive advising had indirect effects on students’ 4-year graduation rates through its impact on students’ self-efficacy and the serial path involving students’ self-efficacy and their academic goals. Our results suggest that if institutions want to ensure they maximize 4-year graduation rates, helping students understand that it is possible to graduate in 4 years is critical.