Age-Moderation of Genetic and Environmental Contributions to Cognitive Functioning in Mid- and Late-Life for Specific Cognitive Abilities.

Age moderation of genetic and environmental contributions to Digits Forward, Digits Backward, Block Design, Symbol Digit, Vocabulary, and Synonyms was investigated in a sample of 14,534 twins aged 26 to 98 years. The Interplay of Genes and Environment across Multiple Studies (IGEMS) consortium contributed the sample, which represents nine studies from three countries (USA, Denmark, and Sweden). Average test performance was lower in successively older age groups for all tests. Significant age moderation of additive genetic, shared environmental, and non-shared environmental variance components was observed, but the pattern varied by test. The genetic contribution to phenotypic variance across age was smaller for both Digit Span tests, greater for Synonyms, and stable for Block Design and Symbol Digit. The non-shared environmental contribution was greater with age for the Digit Span tests and Block Design, while the shared environmental component was small for all tests, often more so with age. Vocabulary showed similar age-moderation patterns as Synonyms, but these effects were nonsignificant. Findings are discussed in the context of theories of cognitive aging.

Understanding The Role of Mate Selection Processes in Couples' Pair-Bonding Behavior.

Couples are similar in their pair-bonding behavior, yet the reasons for this similarity are often unclear. A common explanation is phenotypic assortment, whereby individuals select partners with similar heritable characteristics. Alternatively, social homogamy, whereby individuals passively select partners with similar characteristic due to shared social backgrounds, is rarely considered. We examined whether phenotypic assortment and/or social homogamy can contribute to mate similarity using a twin-partner design. The sample came from the Twin and Offspring Study in Sweden, which included 876 male and female monozygotic and same-sex dizygotic twins plus their married or cohabitating partners. Results showed that variance in pair-bonding behavior was attributable to genetic and nonshared environmental factors. Furthermore, phenotypic assortment accounted for couple similarity in pair-bonding behavior. This suggests that individuals' genetically based characteristics are involved in their selection of mates with similar pair-bonding behavior.

Genetic and environmental influences on applied creativity: A reared-apart twin study.

Applied creativity involves bringing innovation to real-life activities. The first reared-apart twin study assessing genetic and environmental origins of applied creativity, via Draw-a-House (DAH) and Draw-a-Person (DAP) tasks, is presented. Participants included 69 MZA and 53 DZA twin pairs from the Minnesota Study of Twins Reared Apart. Drawings were evaluated by four artists and four non-artists. Genetic effects were demonstrated for the DAP (.38-.47), but not for the DAH. Creative personality showed genetic effects (.50), and modest, but significant correlations with scores on the two drawings (rs = .17-.26). Both genetic and nonshared environmental influences underlie variance in applied creativity. Individuals concerned with enhancing creativity among students and others may better understand individual differences in performance and training.

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.

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.

Neuroticism and Extraversion Share Genetic and Environmental Effects with Negative and Positive Mood Spillover in a Nationally Representative Sample.

Work-family spillover research focuses on how negative and positive moods in one life domain carry over to another domain. Domain-specific etiologies (e.g., family conflict) are often emphasized to explain spillover. Yet, strong correlations exist between spillover variables of the same emotional valence and originating from different domains, suggesting individual differences in the tendencies to prolong mood-states. The current study (N=1143 individuals) examined whether these general tendencies are associated with neuroticism and extraversion, and how genetic and environmental effects contribute to these associations. Findings revealed that neuroticism and extraversion are related to these tendencies through genetic and environmental pathways.

Understanding Associations among Family Support, Friend Support, and Psychological Distress.

Emotional support from family and friends is associated with lower psychological distress. This study examined whether genetic and environmental influences explain associations among family support, friend support, and psychological distress. Data were drawn from the Midlife Development in the United States (MIDUS) study and included 947 pairs of MZ, same-sex DZ, and opposite-sex DZ twins. Results showed that a genetic factor explains the relationship between friend support and psychological distress, independent of family support. Alternatively, a nonshared environmental factor accounts for an association among family support, friend support, and psychological distress. Thus, heritable factors shape a distinct relationship between friend support and psychological distress, but unique experiences contribute to a link among family support, friend support, and psychological distress.

Parental criticism is an environmental influence on adolescent somatic symptoms.

Previous studies have suggested that parental criticism leads to more somatic symptoms in adolescent children. However, this research has not assessed the direction of causation or whether genetic and/or environmental influences explain the association between parental criticism and adolescent somatic symptoms. As such, it is impossible to understand the mechanisms that underlie this association. The current study uses the Extended Children of Twins design to examine whether parents' genes, adolescents' genes, and/or environmental factors explain the relationship between parental criticism and adolescent somatic symptoms. Participants came from 2 twin samples, including the Twin and Offspring Study in Sweden (N = 868 pairs of adult twins and each twin's adolescent child) and from the Twin Study of Child and Adolescent Development (N = 690 pairs of twin children and their parents). Findings showed that environmental influences account for the association between parental criticism and adolescent somatic symptoms. This suggests that parents' critical behaviors exert a direct environmental effect on somatic symptoms in adolescent children. Results support the use of intervention programs focused on parental criticism to help reduce adolescents' somatic symptoms.

Gene - Environment Interplay, Family Relationships, and Child Adjustment.

This paper reviews behavioral genetic research from the past decade that has moved beyond simply studying the independent influences of genes and environments. The studies considered in this review have instead focused on understanding gene - environment interplay, including genotype - environment correlation ( rGE) and genotype × environment interaction (G × E). Studies have suggested that rGE is an important pathway through which family relationships are associated with child adjustment. Also important are direct causal influences of family relationships on child adjustment, independent of genetic confounds. Other studies have indicated that genetic and environmental influences on child adjustment are moderated by different levels of family relationships in G × E interactions. Genetically informed studies that have examined family relations have been critical to advancing our understanding of gene - environment interplay.

The role of aggressive personality and family relationships in explaining family conflict.

This study investigated whether genetic and environmental influences on global family conflict are explained by parents' personality, marital quality, and negative parenting. The sample comprised 876 same-sex pairs of twins, their spouses, and one adolescent child per twin from the Twin and Offspring Study in Sweden. Genetic influences on aggressive personality were correlated with genetic influences on global family conflict. Nonshared environmental influences on marital quality and negative parenting were correlated with nonshared environmental influences on global family conflict. Results suggest that parents' personality and unique experiences within their family relationships are important for understanding genetic and environmental influences on global conflict in the home.

Genetic and environmental influences on global family conflict.

This study examined genetic and environmental influences on global family conflict. The sample comprised 872 same-sex pairs of twin parents, their spouses/partners, and one adolescent child per twin from the Twin and Offspring Study in Sweden. The twins, spouses, and child each reported on the degree of family conflict, and there was significant agreement among the family members' ratings. These shared perspectives were explained by one common factor, indexing global family conflict. Genetic influences explained 36% of the variance in this common factor, suggesting that twins' heritable characteristics contribute to family conflict, via genotype-environment correlation. Nonshared environmental effects explained the remaining 64% of this variance, indicating that twins' unique childhood and/or current family experiences also play an important role.