Gene flow by selective emigration as a possible cause for personality differences between small islands and mainland populations

Whether personality differences exist between populations is a controversial question. Even though such differences can be measured, it is still not clear whether they are due to individual phenotypic responses to the environment or whether they have a genetic influence. In a population survey we compared the personality traits of inhabitants of an Italian archipelago (the three Egadi islands; N = 622) with those of the closest mainland population (Trapani area; N = 106) and we found that personality differences between small populations can be detected. Islanders scored significantly lower on the personality traits of openness to experience and extraversion and higher on conscientiousness. We suggest that these personality trait differences could be an adaptive response to a confined socio‐environmental niche, genetically produced by a strong, non‐random gene flow in the last 20–25 generations, rather than the flexible response of islanders to environmental variables. To test this hypothesis, we compared subsets of the islander population classified by ancestry, birthplace, immigration and emigration and found that differences in extraversion can be accounted for by gene flow, while openness to experience and conscientiousness can also be accounted for by some gene–environment interactions. We propose a Personality Gene Flow hypothesis suggesting that, in small isolated communities, whenever there is strong, non‐random emigration, paired with weak and random immigration, we can expect rapid genetic personality change within the population. Copyright © 2010 John Wiley & Sons, Ltd.     

Examining cognitive development from a conceptual change point of view: The framework theory approach

Sexual socialization refers to how, through social interaction, an individual acquires and internalizes culture-specific knowledge, values and attitudes about sexuality. Little, however, is known about how an individual's genetic characteristics modify this process, or if individuals gravitate towards specific environments according to their genetic characteristics. The aim was to explore whether adolescents' genetic predispositions modify environmental influences on peer-group sexual attitudes. Using a Finnish population-based sample of twins and their siblings (n = 9534), it was found that genetic effects influenced peer-group sexual attitudes in men (52%) and women (46%), thus offering evidence for gene–environment correlation. Men showed less restricted peer-group sexual attitudes than women. Some indications of different genes influencing environmental exposure in men and women were found.     

多巴胺相关基因甲基化、家庭环境与创造力的关系

“遗传与环境”的争论一直是创造力研究的核心问题, 但目前对于环境以及遗传与环境交互作用对创造力影响的分子生物机制还未有研究涉及。近年来, 随着表观遗传学的兴起, 揭示影响心理行为的表观遗传机制现已成为心理学研究的热点。作为环境与基因组之间的纽带, 表观遗传学研究为揭示环境以及遗传与环境交互作用对创造力影响的分子生物机制提供了机遇。本研究以多巴胺相关基因、家庭环境以及两者对于创造力的交互作用为切入点, 对影响创造力的表观遗传机制进行考察, 并在此基础之上, 对环境以及遗传与环境交互作用对创造力影响的分子生物机制进行探索。具体研究内容包括：(1)通过对多巴胺相关基因甲基化模式与创造力关系的系统考察, 筛选出甲基化模式与创造力有关的基因; (2)对筛选出的基因, 进一步考察其甲基化模式在家庭环境及其遗传多态性与家庭环境交互作用对创造力影响中的中介作用。本研究有助于揭示创造力的表观遗传机制, 深化关于遗传与环境对创造力影响的作用机制的理解。     

Beyond the heritability of life satisfaction – The roles of personality and twin-specific influences

In a behavior genetic design, we investigated individual differences in life satisfaction and its relation to personality with respect to both internal and external influences. We questioned the absence of shared environment and examined the specific contribution of additive and non-additive genetic influences. We also tested for twin-specific environmental influences in a total sample of 1308 dyads including identical and fraternal twins, siblings, mother–child and grandparent–child pairs. The results showed substantial shared environmental influences on life satisfaction that varied between twins and non-twins, supporting twin-specific environmental influences. Additive and non-additive genetic influences on life satisfaction were completely shared with personality. The remaining variance could be explained by unique non-shared environmental influences for life satisfaction independent of personality.     

An exploration of genetic g: Hierarchical factor analysis of cognitive data from the western reserve twin project

Hierarchical factor analyses involving Schmid-Leiman transformations (Schmid & Leiman, 1957) were conducted on specific cognitive abilities data collected in a sample of 148 identical (MZ) and 135 same-sex fraternal (DZ) twin pairs. Two main questions were addressed: First, are genetic influences on specific cognitive abilities simply a reflection of their g loading, or are different sets of genes affecting separate abilities? Second, to the extent that specific cognitive abilities are affected by common genetic variance, how similar is the common genetic factor to a phenotypic factor reflecting g? Model fitting results suggest that genetic influences on specific abilities are a reflection of both general intelligence and genetic influences specific to separate abilities and that loadings on the common genetic factor are more highly correlated with phenotypic g loadings than are common environmental factor loadings.     

Normal and abnormal personality traits: evidence for genetic and environmental relationships in the Minnesota Study of Twins Reared Apart

ABSTRACT Recent studies have demonstrated substantial correlations between normal and abnormal personality traits. Yet little is known about how these correlations are mediated genetically and environmentally: Do normal and abnormal personality traits stem from the same underlying genes and environments? We addressed this question using data from 128 monozygotic and dizygotic twin pairs in the Minnesota Study of Twins Reared Apart (MISTRA). Additive genetic and nonshared environmental correlations between scales of the Minnesota Multiphasic Personality Inventory (MMPI)—an index of abnormal personality—and the Multidimensional Personality Questionnaire (MPQ)—an index of normal personality—were estimated. Results indicated that phenotypic correlations between normal and abnormal personality were mediated by genetic as well as environmental factors, although the magnitude of genetic mediation tended to be larger overall. Moreover, the patterns of phenotypic, genetic, and environmental relationships among the scales were similar, suggesting that influences on normal and abnormal personality act through systems common to both. It is suggested that future research focus on the neurogenetic substrates of these shared systems and how dysfunction in these systems influences development of disordered personality.     

Individual Resiliency Factors from a Genetic Perspective: Results from a Twin Study

This article is part of the Twin Mother's Study, a study that examines influences on maternal adjustment. A number of studies have investigated the importance of genetic factors for mental health, but few of these examine how genes and the environment influence resiliency/salutogenic factors. This article investigates the relative importance of genetic and environmental influences on resiliency/salutogenic factors. This study includes 326 twin pairs (150 monozygotic and 176 dizygotic) who are mothers, who are living with their spouse, and who are part of the Swedish twin register. Using self‐report structured questionnaires, we assessed salutogenic factors, depression, and quality of life; however, we analyzed the questionnaires completed by the mothers. Statistical analyses were conducted using structural equation modeling. We conclude that nonshared environmental components were of principal importance in individual resiliency/salutogenic factors in a genetically informative design, but we also noted that genetic influences were important. The shared environment had mainly no effect.     

Behavioral genetic analyses of prosocial behavior in adolescents

Prosocial behavior is an important aspect of normal social and psychological development. Adult and child twin studies typically estimate the heritability of prosocial behavior to be between 30 and 50%, although relatively little is known about genetic and environmental influences upon prosocial behavior in adolescence. We therefore examined reports of prosocial behavior in a large longitudinal family study of 1160 adolescent twin pairs (aged between 13 and 19 years). Prosocial behavior was assessed at two time points by self‐report and at the second time point by additional parent‐ratings using the Strengths and Difficulties Questionnaire (SDQ; Goodman, 1997 ). Adolescent females were reported to be significantly more prosocial than males (p < .001). Univariate analyses primarily showed moderate heritability and large nonshared environmental influences. There was a moderate genetic correlation between self‐ and parent‐reported prosocial behaviour, suggesting that both types of rater were tapping into genetically overlapping constructs. Longitudinal analyses revealed that continuity was largely explained by genes. Unique environmental influences were predominantly time‐specific and were the major source of individual differences.     

Genetic Influences on Anxiety in Children: What we’ve Learned and Where we’re Heading

Anxiety is a common problem, typically beginning early in life. This article explores reasons for individual differences in levels of anxiety among children, by reviewing the genetic literature. The plethora of research to date has demonstrated clearly that both genes and environmental influences play important roles in explaining differences in levels of anxiety of various types among children. This has encouraged researchers to search for specific genes and environmental influences upon anxiety. Despite important progress in identifying links between anxiety and specific genes—including associations between serotonin and dopamine genes and different symptoms of anxiety—overall, progress has been slow because multiple genes of small effect size are likely to influence anxiety. This article explains how the hunt for genes involved in anxiety is likely to benefit from genetically sensitive research, which examines the co-occurrence of symptoms; includes measures of the environment; and examines endophenotypes and risk pathways.     

Genetic and environmental influences on rumination and its covariation with depression

This study examined the extent to which rumination and depression share genetic and environmental influences in a community sample of adult twins (N = 663). Twins completed multiple rumination questionnaires, a depressive symptoms questionnaire and a diagnostic interview. Rumination was moderately heritable (h² = .37–.41 for the latent variable) and substantially influenced by nonshared environmental factors, and these results were consistent across different measures. Nonshared environmental influences on rumination were larger for women than men. Depressive symptoms and diagnosis were influenced by genetic and nonshared environmental factors (h² = .30–.45). The genetic correlations between rumination and depression were moderate to large (rA = .40–.82), suggesting that a substantial proportion of the genetic influences on rumination overlap with those on depression. Results were similar when examining self-reported depressive symptoms and interview-based diagnosis of major depressive disorder. These results highlight the importance of rumination in the integration of cognitive and genetic models of depression risk.     

Genetic and Environmental Pathways Underlying Personality Traits and Perceived Stress: Concurrent and Longitudinal Twin Studies

The present study examined the genetic and environmental etiology underlying the Big Five personality traits and perceived stress, concurrently and longitudinally. In study 1, we used the twin sample from the National Longitudinal Study of Adolescent to Adult Health (Add Health IV) data. The results indicated that about 70% of the association between the Big Five personality traits and perceived stress was due to genetic influences. In study 2, we used the twin sample from the Midlife in the United States Survey (MIDUS I and II) to examine the genetic and environmental influences underlying the longitudinal relations between the Big Five personality traits and perceived stress. The results suggested that continuity in perceived stress was primarily accounted for by genetic influences, and changes in perceived stress were mainly due to nonshared environmental influences. The continuity in the association between the five personality traits and perceived stress was largely accounted for by genetic factors, and nonshared environmental factors made greater contributions to changes in the association between personality traits and perceived stress. Among the Big Five personality traits, the genetic components in conscientiousness and neuroticism made substantial contributions to the genetic link between personality traits and perceived stress across both studies. Copyright © 2017 European Association of Personality Psychology     

Genetic and environmental structure of adjectives describing the domains of the Big Five Model of personality: A nationwide US twin study

We applied multivariate models specifying genetic and environmental influences on adjectives describing each of the five personality domains specified in the Big Five Model of personality (BFM; Extraversion, Neuroticism, Agreeableness, Conscientiousness, and Openness). We selected the specific models to partition the observed covariance among the adjectives describing each domain into genetic and environmental components in order to assess the etiologic basis for each domain's phenotypic coherence. The sample on which our analyses were based was part of the National Survey of Midlife Development in the United States (MIDUS). It consisted of 315 monozygotic and 275 same-sex dizygotic twin pairs. Results revealed both common and specific genetic and environmental influences for each domain, suggesting that all of the domains are etiologically complex. Models specifying the domains as latent phenotypic constructs fit more poorly than models suggesting more complex structures for all domains except Extraversion and Neuroticism. These results raise questions about the BFM as a coherent model of genetic and environmental influences on personality or, alternatively, about the etiological unity of latent phenotypic personality trait constructs beyond Extraversion and Neuroticism.     

The Behavioral Genetics of Alcoholism

Twin and adoption studies consistently implicate the importance of genetic influences on alcoholism risk, especially in men. Heritability estimates suggest that approximately 50% to 60% of the variability in alcoholism liability is associated with genetic factors. Although there has been progress in identifying specific genes that predispose toward alcoholism, we know relatively little about the nature of the genetic influence on alcoholism risk. We also know relatively little about how genetic factors combine with environmental factors to affect alcoholism risk. Genotype-environment interaction models posit that alcoholism occurs when individuals both inherit a vulnerability to develop alcoholism and are reared in a provocative environment. Such models hold great promise for understanding alcoholism's etiology.     

Social relationships,stressful life events,and self-reported physical health: Genetic and environmental influences

Abstract

This study investigates how the associations between self-reported health, stressful life events, and social relationships are mediated by genetic and environmental influences and how much of the variance in health is in common with variation in these psychosocial factors. The analyses are based on questionnaire data from 576 pairs of twins reared apart and twins reared together. The data revealed that for men environmental influences were solely important for variation in the psychosocial measures and were the primary mediators of the relationship with health. For women, on the other hand, a substantial portion of the variance in the psychosocial factors was due to genetic influences and these influences also contributed to the bulk of the correlations with health. The gender differences for the relationships and their mediation indicate that what should be regarded as a psychosocial factor of importance for health might differ between genders.     

The Heritability of Job Satisfaction Reconsidered: Only Unique Environmental Influences Beyond Personality

Purpose

The purpose of this study was to investigate the degree to which genetic and environmental influences explain differences in job satisfaction and its relationship to personality in order to explain the heritability of job satisfaction.

Design

Behavior genetic analyses are based on a dataset containing 622 individuals, including 185 MZ (M = 39.5 years) and 126 DZ twin pairs (M = 40.1 years).

Findings

The results showed that all genetic influences (28 %) on job satisfaction could be explained by its relation to personality, especially Neuroticism, Extraversion, and Conscientiousness, representing a high genetic overlap between job satisfaction and personality. Non-shared environmental influences explained the remaining three fourths of the variance.

Implications

By showing that genetic influences of job satisfaction overlap completely with personality, including common non-additive genetic influences, the results support an interactionist view of job satisfaction in that both situational and dispositional determinants of job satisfaction are relevant.

Originality

In contrast to previous studies, we used a more appropriate behavior genetic approach meaning that our approach allows to directly estimate parameters of specific and common (additive and non-additive) genetic and environmental influences. Building on this, interpretations of behavior genetic findings were explained in detail to avoid common misunderstandings.

     

Dopamine and serotonin systems modify environmental effects on human behavior: A review

The relative influences of genetic and environmental factors in the development of human behavior have been a long‐term topic for an intense debate. Recent behavioral genetic studies suggest focusing on the joint effect of genes and environment, and especially on the life‐course developmental interplay between nature and nurture. Vulnerability to environmental adversities and sensitivity to its benefits may be conditional on genetic background, and regarding psychological outcomes, these kinds of gene × environment interactions may be of higher importance than direct gene–trait associations. In our recent series of studies, we have shown that different variants of serotonergic and dopaminergic genes may moderate the influence of environmental conditions on a range of psychological outcomes, i.e. temperament, depression, hostility, and educational attainment. These studies suggest that depending on their genotype, people may be differentially sensitive to the environmental conditions they encounter. In the light of these results it seems highly plausible that the effects of genes may become evident only when studied in the context of environmental factors.     

Behavioral genetic methods

Traditional behavioral genetic methods involve the use primarily of family, twin, and adoption correlations to estimate the relative contributions of genetic and environmental influences in the etiology of individual differences. These methods and representative results for personality are described. However, newer methods are emphasized: structural models and model-fitting, multivariate analysis, genetic change and continuity in development, shared and non-shared components of environmental variance, and genetic components of "environmental" variation. Because most applications of these behavioral genetic methods to the study of personality involve self-report omnibus questionnaires, an important direction for future research in this area is to use these methods to explore new issues and new measures that have emerged from personality theory and research during the past decade.     

Why is personality tied to sleep quality? A biometric analysis of twins

Despite consistent links between personality traits and poor sleep, little is known about genetic and environmental influences that may produce them. This study examined how much genetic background and environmental experiences contributed to phenotypic linkages between personality and subjective sleep quality. Seven hundred and thirty-four twin pairs from the Minnesota Study of Twin Aging and Development rated their sleep quality and provided personality reports. Bi-variate analyses revealed that genetic factors accounted for the majority of observed associations between subjective sleep quality and traits, but also that non-shared environmental experience played a role that varied across traits. The findings strongly implicate genotype in tying subjective sleep quality to personality variation, alongside non-shared environmental influences, and suggest indicate influences unique to individual traits.     

Personality Change in Middle Adulthood: With Focus on Differential Susceptibility

Abstract

Little attention has been paid to middle adulthood in research on personality stability and change. In addition, previous research on individual differences in personality change has not fully explained its variability. This study focused on the differential susceptibility model, which suggests that individual susceptibility interacts with environmental factors and produces variability in outcomes, and investigated individual differences in personality change with a middle adult sample. A total of 1051 Japanese middle adults (M?=?41.61?years; SD = 5.31; range 30–50?years; 534 females) participated in this two-wave short-term longitudinal study. Latent change score model analyses revealed substantial mean-level declines in Agreeableness and Honesty–Humility. Moreover, the results showed that the influences of some life events on personality change are moderated for better and for worse by individual susceptibility to one’s environment. These findings suggest that the trends of personality development may differ between Western and non-Western countries and that differential susceptibility model may play an important role in deriving individual differences in personality stability and change.