Prosocial behavior from early to middle childhood: Genetic and environmental influences on stability and change.

Prosocial behavior is important for the functioning of society. This study investigates the extent to which environment shared by family members, nonshared environment, and genetics account for children's prosocial behavior. The prosocial behavior of twins (9,424 pairs) was rated by their parents at the ages of 2, 3, 4, and 7 and by their teachers at age 7. For parent ratings, shared environmental effects decreased from .47 on average at age 2 to .03 at age 7, and genetic effects increased from .32 on average to .61. The finding of weak shared environmental effects and large heritability at age 7 was largely confirmed through the use of teacher ratings. Using longitudinal genetic analyses, the authors conclude that genetic effects account for both change and continuity in prosocial behavior and nonshared environment contributes mainly to change. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic and Environmental Mechanisms Underlying Stability and Change in Problem Behaviors at Ages 3, 7, 10, and 12.

Maternal ratings on internalizing (INT) and externalizing (EXT) behaviors were collected in a large, population-based longitudinal sample. The numbers of participating twin pairs at ages 3, 7, 10, and 12 were 5,602, 5,115, 2,956, and 1,481, respectively. Stability in both behaviors was accounted for by genetic and shared environmental influences. The genetic contribution to stability (INT: 43%; EXT: 60%) resulted from the fact that a subset of genes expressed at an earlier age was still active at the next time point. A common set of shared environmental factors operated at all ages (INT: 47%; EXT: 34%). The modest contribution of nonshared environmental factors (INT: 10%; EXT: 6%) could not be captured by a simple model. Significant age-specific influences were found for all components, indicating that genetic and environmental factors also contributed to changes in problem behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The developmental origins of a disposition toward empathy: Genetic and environmental contributions.

The authors investigated the development of a disposition toward empathy and its genetic and environmental origins. Young twins' (N = 409 pairs) cognitive (hypothesis testing) and affective (empathic concern) empathy and prosocial behavior in response to simulated pain by mothers and examiners were observed at multiple time points. Children's mean level of empathy and prosociality increased from 14 to 36 months. Positive concurrent and longitudinal correlations indicated that empathy was a relatively stable disposition, generalizing across ages, across its affective and cognitive components, and across mother and examiner. Multivariate genetic analyses showed that genetic effects increased, and that shared environmental effects decreased, with age. Genetic effects contributed to both change and continuity in children's empathy, whereas shared environmental effects contributed to stability and nonshared environmental effects contributed to change. Empathy was associated with prosocial behavior, and this relationship was mainly due to environmental effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quantitative Genetic Analysis of Latent Growth Curve Models of Cognitive Abilities in Adulthood.

Though many cognitive abilities exhibit marked decline over the adult years, individual differences in rates of change have been observed. In the current study, biometrical latent growth models were used to examine sources of variability for ability level (intercept) and change (linear and quadratic effects) for verbal, fluid, memory, and perceptual speed abilities in the Swedish Adoption/Twin Study of Aging. Genetic influences were more important for ability level at age 65 and quadratic change than for linear slope at age 65. Expected variance components indicated decreasing genetic and increasing nonshared environmental variation over age. Exceptions included one verbal and two memory measures that showed increasing genetic and nonshared environmental variance. The present findings provide support for theories of the increasing influence of the environment with age on cognitive abilities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Beyond nature versus nurture: DF analysis of nonshared influences on problem behaviors.

J. C. DeFries and D. W. Fulker's (see record 1986-23496-001) regression model (later termed "DF analysis" by R. Plomin and R. Rende [see PA, Vol 78:18462]) used kinship pair data to separate heredity and shared environmental influences. This article extends DF analysis to include measured indicators of the nonshared environment. These indicators represent specific sources of environmental influence that cause related children to be different from one another. Two studies are presented which used twin, full-sibling, half-sibling, and cousin pairs from over 7,000 5–12 yr old children in the National Longitudinal Survey of Youth. Study 1 was a validity analysis of kinship height and weight data. Study 2 was a DF analysis of problem behavior scores. Spanking, reading, and quality of the home environment were shown to account for nonshared variance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Continuity and change in children's social maladjustment: A developmental behavior genetic study.

Two developmental models were used to study genetic and environmental mechanisms underlying continuity and change in children's maladjustment. The transmission model assumed that successive levels of functioning were causally linked and that earlier experiences or prior genetic influences affected later maladjustment. The liability model related continuity in problem behavior to stable underlying environmental or genetic factors. The analyses pertained on average to 436 pairs of full siblings, 119 pairs of half siblings, and 122 pairs of cousins for whom maternal ratings of problem behaviors were available at ages 4–6, 6–8, and 8–10. Nonshared environmental influences appeared to be most important for changes in children's problem behaviors and did not have significant effects on age-to-age continuity. To represent the genetic and shared environmental mechanisms underlying stability in problem behavior, the authors preffered liability models without time specific effects. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shared experiences and the similarity of personalities: A longitudinal study of married couples.

Do spouses become more similar over time? What processes contribute to enduring similarities between them? Using the 20-yr Kelly Longitudinal Study of couples, no support for the hypothesis that couples increasingly resemble each other with time was found. Rather, couples maintain the same degree of similarity across 20 yrs. Structural equation analyses suggest that the shared environmental experiences of couples play a significant role in maintaining these similarities over time. The authors distinguish the shared marital environment from the shared rearing environment and consider developmental and dynamic-relational factors that moderate the relative importance of nonshared and shared environmental experiences in life-span personality development. Whereas nonshared influences in one's family of origin contribute to development in childhood and adolescence, shared influences in one's family of destination may contribute a great deal to development in adulthood. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic and Environmental Contributions to General Cognitive Ability Through the First 16 Years of Life.

The genetic and environmental contributions to the development of general cognitive ability throughout the first 16 years of life were examined using sibling data from the Colorado Adoption Project. Correlations were analyzed along with structural equation models to characterize the genetic and environmental influences on longitudinal stability and instability. Intraclass correlations reflected both considerable genetic influence at each age and modest shared environmental influence within and across ages. Modeling results suggested that genetic factors mediated phenotypic stability throughout this entire period, whereas most age-to-age instability appeared to be due to nonshared environmental influences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stability and change in religiousness during emerging adulthood.

Understanding the development of religiousness is an important endeavor because religiousness has been shown to be related to positive outcomes. The current study examined mean-level, rank-order, and individual-level change in females' religiousness during emerging adulthood. Genetic and environmental influences on religiousness and its change and stability were also investigated. Analyses were completed with an epidemiological study of 2 cohorts of twins: 1 assessed at ages 14 and 18 and a 2nd at 20 and 25. Mean levels of religiousness decreased significantly with age, while rank-order stability was high. Individual-level change was also evident. Analyses also supported the hypotheses that more change would occur in the younger cohort compared with the older cohort and that more change would occur in religious service attendance than the general index of religiousness. Twin analyses suggested that the heritability of religiousness increased with age, while the shared environmental influences decreased. For the younger cohort, change was genetic in origin, while stability was environmental. In the older cohort, change was influenced by nonshared environment and stability by both genes and family environment. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic and environmental influences on girls' and boys' gender-typed and gender-neutral values.

In this first investigation of genetic and environmental influences on children's values, 271 German twin pairs (50.2% boys) reported their values at ages 7–11 years using the Portrait Values Questionnaire (Schwartz & Rubel, 2005). We distinguished between gender-neutral (conservation vs. openness to change) and gender-typed (self-transcendence vs. self-enhancement) values. Boys differed from girls in the importance given to gender-typed benevolence, achievement, and power values. Gender-neutral values showed moderate (.34) and gender-typed values showed higher (.49) heritability, with nonshared environment and error accounting for the remaining variance. For both sexes, substantial genetic effects accounted for the importance children gave to their respective gender-stereotypical end of the self-transcendence versus self-enhancement dimension. However, dramatic sex differences emerged in the gender-atypical end of the distribution. For girls, low self-transcendence (high gender-atypical values) showed a large (.76) group heritability. For boys, gender-atypical values (high self-transcendence) showed no heritability and a modest (.10) shared environment effect. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Nonshared environment: A theoretical, methodological, and quantitative review.

When genetic similarity is controlled, siblings often appear no more alike than individuals selected at random from the population. Since R. Plomin and D. Daniels' seminal 1987 review, it has become widely accepted that the source of this dissimilarity is a variance component called nonshared environment. The authors review the conceptual foundations of nonshared environment, with emphasis on distinctions between components of environmental variance and causal properties of environmental events and between the effective and objective aspects of the environment. A statistical model of shared and nonshared environmental variables is developed. A quantitative review shows that measured nonshared environmental variables do not account for a substantial portion of the nonshared variability posited by biometric studies of behavior. Other explanations of the preponderance of nonshared environmental variability are suggested. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic and environmental influences on positive and negative affect: Support for a two-factor theory.

Studied genetic and environmental etiologies of positive and negative affect, as measured by the Bradburn Affect Balance Scale, to gain understanding of a 2-factor theory of well-being. It was hypothesized that negative affect would demonstrate significant genetic and environmental variance and positive affect would be explained primarily by environmental influences. Data were combined from 105 pairs of twins (aged 18–72 yrs) and 220 multigenerational families (aged 16–98 yrs). Simultaneous model fitting indicated significant heritable effects for negative affect and a significant effect of common environment for twins. Significant effects for positive affect included common environment (for parents and offspring and for twin pairs) and assortative mating. These results, documenting differential genetic and environmental influences on positive and negative affect, provide further support for their being separate components of well-being. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

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. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Child and adolescent conduct disorder substantially shares genetic influences with three socioemotional dispositions.

In a representative sample of twin children and adolescents, we tested the hypothesis that a substantial proportion of the genetic and environmental influences underlying conduct disorder (CD) are shared with three socioemotional dispositions: Prosociality, Negative Emotionality, and Daring. Caretaker ratings of each dispositional dimension were uniquely associated with a latent CD dimension that included both caretaker- and youth-reports of CD as indicators. Behavior genetic analyses indicated that moderate-to-high additive genetic and moderate nonshared environmental influences underlie all three dispositions and CD, with modest shared environmental influences on Prosociality. Forty percent of the additive genetic influences and all of the nonshared environmental influences on the latent CD dimension were shared in common with the three socioemotional dispositions. The finding that CD shares a substantial proportion of its genetic influences with three distinct socioemotional dispositions suggests new perspectives on the heterogeneous etiology of CD and new approaches to exploring its specific etiological mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic and environmental influences on antisocial behavior: A meta-analysis of twin and adoption studies.

A meta-analysis of 51 twin and adoption studies was conducted to estimate the magnitude of genetic and environmental influences on antisocial behavior. The best fitting model included moderate proportions of variance due to additive genetic influences (.32), nonadditive genetic influences (.09), shared environmental influences (.16), and nonshared environmental influences (.43). The magnitude of familial influences (i.e., both genetic and shared environmental influences) was lower in parent-offspring adoption studies than in both twin studies and sibling adoption studies. Operationalization, assessment method, zygosity determination method, and age were significant moderators of the magnitude of genetic and environmental influences on antisocial behavior, but there were no significant differences in the magnitude of genetic and environmental influences for males and females. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Subjective well-being is heritable and genetically correlated with dominance in chimpanzees (Pan troglodytes).

The hypothesis that subjective well-being (SWB) is heritable and genetically correlated with Dominance was tested using 128 zoo chimpanzees. Dominance was a chimpanzee-specific personality factor including items reflecting Extraversion and low Neuroticism. SWB was measured with a 4-item scale. The best behavior genetic model included additive genetic and nonshared environmental effects for SWB and Dominance, marginal maternal effects for SWB, a high genetic correlation, and a low nonshared environmental correlation. Results indicated that the shared variance between SWB and Dominance was a consequence of common genes and that the unique variance between SWB and Dominance was a consequence of the nonshared environment. These findings indicate that common genes may underlie the correlation between human personality factors and SWB. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A genetic study of maternal and paternal ratings of problem behaviors in 3-year-old twins.

Genetic and environmental influences on problem behaviors were studied in 3-yr-old twins. Fathers' and mothers' ratings of problem behaviors in twins (236 monozygotic [MZ] girls, 210 MZ boys, 238 dizygotic [DZ] girls, 265 DZ boys, and 409 DZ opposite sex pairs) were obtained with the Child Behavior Checklist for Ages 2–3 (T. M. Achenbach, 1992). Twin correlations and results from a model fitting approach showed that genetic, shared environmental, and nonshared environmental influences accounted on average for about 64%, 9%, and 27% of the variance. Although shared environmental influences were small for most scales, they were important for Total Problems and somewhat larger for Externalizing than for Internalizing behaviors. Significant sex differences in genetic and environmental influences and evidence for sibling contrast effects were found for the Overactive scale. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A study of genetic and environmental effects on the co-occurrence of problem behaviors in three-year-old-twins.

The authors examined the genetic and environmental causes of the co-occurrence of problem behaviors in children. The analyses involved mother and father ratings of Oppositional, Withdrawn/Depressed, Aggressive, Anxious, Overactive, and Sleep Problems in 446 monozygotic and 912 dizygotic pairs of 3-year-old twins. Genetic factors contributed on average .150 (37.3%), shared environment .206 (51.2%), and nonshared environment .046 (11.4%) to the phenotypic correlations between the syndromes. Genetic and environmental factors caused different groupings. Internalizing and Externalizing groupings were indicative of nonshared environmental factors; clusters of problem behaviors with either the Aggressive or Anxious symptoms were most suggestive of genetic factors, and high scores on all syndromes indicated shared environmental influences. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Developmental genetic studies of adult personality.

Investigated genetic determinants of personality development and vulnerability to environmental influences during young adulthood, using a longitudinal twin study design. 133 college-age twin pairs completed an abbreviated MMPI twice over a period of 4.5 yrs at ages 20 and 25 yrs. Of the 6 MMPI scales investigated, significant genetic variance was found for 4 at both time periods (Wiggins's Social Maladjustment, Schizophrenia, Welsh A, and D?? scales). Two scales (Psychopathic Deviate and Wiggins's Religiosity) showed significant genetic variance at age 20 but not at age 25. There were no significant genetic influences on directional developmental change over time, and instead, idiosyncratic environmental influences appeared most important for the developmental profiles. In contrast, significant genetic influences were present for generalized vulnerability, or instability, for the Sc scale. (61 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)