Adolescent personality moderates genetic and environmental influences on relationships with parents

In contrast with early theories of socialization that emphasized the role of parents in shaping their children's personalities, recent empirical evidence suggests an evocative relationship between adolescent personality traits and the quality of the parent-adolescent relationship. Research using behavior genetic methods suggests that the association between personality and parenting is genetically mediated, such that the genetic effects on adolescent personality traits overlap with the genetic effects on parenting behavior. In the current study, the authors examined whether the etiology of this relationship might change depending on the adolescent's personality. Biometrical moderation models were used to test for gene- environment interaction and correlation between personality traits and measures of conflict, regard, and involvement with parents in a sample of 2,452 adolescents (M age = 17.79 years). They found significant moderation of both positive and negative qualities of the parent-adolescent relationship, such that the genetic and environmental variance in relationship quality varied as functions of the adolescent's levels of personality. These findings support the importance of adolescent personality in the development of the quality of the parent-adolescent relationship.     

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.     

Phenotypic, genetic, and nonshared environmental parallels in the structure of personality: a view from the multidimensional personality questionnaire

How closely do observed, phenotypic personality structures correspond with underlying, genetic, and environmental personality structures? This question was addressed using data from 2,490 pairs of twins from the Minnesota Twin Registry, who completed A. Tellegen's (1982) Multidimensional Personality Questionnaire (MPQ). Phenotypic, additive genetic, and nonshared environmental correlations were computed among the MPQ's eleven primary scales. Principal component analyses of all three matrices revealed three broad, higher-order components that were readily interpreted as negative emotionality, positive emotionality, and constraint. The components from all three matrices were highly comparable, suggesting that the observed, phenotypic structure of personality corresponds closely with the underlying, etiological structure of personality.     

Personality related traits as predictors of music practice: Underlying environmental and genetic influences

Little is known about reasons for individual differences in practice behavior – why do some individuals practice more than others? Here we explore personality related traits such as openness, motivation and flow proneness as well as IQ as potential predictors of music practice. Using a large Swedish twin cohort of more than 10,500 individuals we also estimated genetic and environmental influences underlying such associations. Significant associations with music practice were found for IQ, intrinsic motivation, music flow, and openness. With all predictors in the same model (including sex and age) we could explain about 25% of variance in music practice. However, IQ and intrinsic motivation became non-significant in the full model, with music specific flow being the strongest predictor of music practice. Multivariate genetic modeling with the two remaining significant predictors (openness and music flow) and music practice suggested that the associations between the variables were largely due to shared genetic influences with some additional non-shared environmental influences. Our findings suggest that common genes may influence both music practicing behavior and traits related to artistic interests and musical enjoyment (flow).     

Genetic and environmental influences on the positive traits of the values in action classification,and biometric covariance with normal personality

Virtually all human individual differences have been shown to be moderately heritable. Much of this research, however, focuses on measures of dysfunctional behavior and relatively fewer studies have focused on positive traits. The values in action (VIA) project is a comprehensive and ambitious classification of 24 positive traits, also known as character strengths (Peterson, C., & Seligman, M. E. P. (2004). Character strengths and virtues: A handbook and classification. Washington, DC: American Psychological Association), the majority of which have received no behavior genetic attention. Using a sample of 336 middle-aged twins drawn from the Minnesota Twin Registry who completed the VIA inventory of strengths, we detected significant genetic and non-shared environmental effects for 21 of 24 character strengths with little evidence of shared environmental contributions. Associations with a previously administered measure of normal personality found moderate phenotypic overlap and that genetic influences on personality traits could account for most, but not all, of the heritable variance in character strengths.     

Trait means and desirabilities as artifactual and real sources of differential stability of personality traits

Using data from 3 personality trait inventories and 7 samples, we show that trait items that have means near the scale midpoint and that vary more in their perceived desirability (e.g., items related to dominance, creativity, traditionalism, and organization) tend to be more stable over time, whereas items with means near the scale maximum or minimum and that vary less in their perceived desirability (e.g., items related to agreeableness, intellect, and reliability) tend to be less stable. Our findings indicate that items with means near the scale maximum or minimum have lower stabilities primarily due to having lower measurement dependability (i.e., short-term stabilities unlikely to reflect true change). However, items varying more in their desirability are more stable even after accounting for measurement dependability, consistent with the view that trait stability is facilitated in part by individuals actively working to develop in the direction they find desirable.     

Genetic and environmental influences on personality profile stability: unraveling the normativeness problem

The present study is the first to disentangle the genetic and environmental influences on personality profile stability. Spanning a period of 10 years, we analyzed the etiology of 3 aspects of profile stability (overall profile stability, distinctive profile stability, and profile normativeness) using self- and peer reports from 539 identical and 280 fraternal twins reared together. This 3-wave multirater twin design allowed us to estimate the genetic and environmental effects on latent true scores of the 3 aspects of profile stability while controlling for method effects and random error. Consistent biometric results were only found for profile normativeness, whereas overall and distinctive profile stability scores turned out to be biased. Over time, we found personality profile normativeness to be relatively stable. This stability was due to both stable genetic and nonshared environmental effects, whereas innovative variance was completely explained by nonshared environmental effects. Our findings emphasize the importance of distinguishing between the different aspects of profile stability, since overall and distinctive stability scores are likely biased due to the normativeness problem. Yet indicating a person's similarity to the average person, the normativeness of a personality profile itself has a psychological meaning beyond socially desirable responding.     

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.     

Herrnstein''s syllogism: genetic and shared environmental influences on IQ, education, and income

Genotypes may influence the phenotypic associations among IQ, education, and income. To investigate this hypothesis, we believe that the appropriate methodology requires estimation of genetic and environmental influences using data able to separate these influences. The National Longitudinal Survey of Youth (NLSY) is a nationally representative sample that contains genetically-informative full- and half-siblings (28–35 years old in 1992; Ns=1943 full-siblings, 129 half-siblings). A biometric genetic model was fit that estimated the shared environmental and genetic variance components of IQ, years of education, and hourly income. The total heritabilities were 0.64 for IQ, 0.68 for education, and 0.42 for income. Heritabilities due to a common genetic factor were 0.35 for IQ, 0.52 for education, and 0.12 for income. Environmental influences due to a common shared environmental factor were 0.23 for IQ, 0.18 for education, and 0.08 for income. The model predicted a correlation of 0.63 between IQ and education and 0.34 between IQ and income. Sixty-eight percent of the former and 59% of the latter was genetically mediated; the remainder was mediated by common shared environment. These findings suggest that social inequality in the United States has its origin in both genetically-based traits and in different environmental backgrounds.     

Nonshared environmental influences and personality differences in adult twins

The twin design was used to examine the importance of different experiences of siblings within the family and to identify relations between twins' personality differences and their differential experiences. A sample of 161 monozygotic and 74 dizygotic twin individuals between the ages of 18 and 75 years retrospectively reported on their different experiences when growing up. The Sibling Inventory of Differential Experience (SIDE) was used for the first time with a sample of twin siblings. In addition, the twins provided self-report measures of affect and personality. In contrast to results from a sibling adoption design, this study of twins showed greater evidence for genetic variance in the SIDE scales. Nevertheless, the SIDE showed significant associations with differences in personality and affect for monozygotic twins, which reflect pure environment-behavior relations.     

Towards a refined structure of personality traits

In this article we pursue two goals. The first is a further articulation of the dimensionality of the Dutch trait domain. The second is a detailed mapping of the factorial trait structure, one which includes intelligible and proper niches for various nuances of the trait language and for different interpretations of the main factors of personality language. In realizing these goals, we discuss the reliance on theory in structuring and modelling the domain in question, the type of model to be used, and the comprehensiveness versus the economy of domain representation. The advantages and disadvantages of the simple structure model and the circumplex model are commented upon, and a new framework that integrates these two models is presented. The present results provide confirmation of the existence of five major dimensions that cover the trait domain: (I) Extraversion or Surgency, (II) Agreeableness, (III) Conscientiousness, (IV) Emotional Stability, and (V) Intellect or Openness to Experience. The newly developed representational model, revealing a refined structure of personality characteristics, not only clarifies some of the problems faced in interpreting the Big Five factors, but also forms a starting point for applications.     

Sociability and positive emotionality: genetic and environmental contributions to the covariation between different facets of extraversion

The relation between sociability and positive affect is one of the most often replicated results of research on personality and subjective well-being. It is shown how behavior genetics can contribute to our understanding of the covariance between sociability and positive emotionality. The results of a multimethod behavior-genetic study with 158 monozygotic and 120 dizygotic twins are reported. In this study, sociability and two components of positive emotionality (positive affect, energy) were assessed by self-report and other report. Additionally, positive state affect was assessed in five situations and aggregated across situations. The results showed that there are strong genetic correlations between all variables. Furthermore, there are substantive correlations between the nonshared environmental components of the different variables. Shared environmental influences, however, seemed to be unimportant for explaining the correlations between sociability and the different components of positive emotionality. The results are discussed with respect to their implications for future research on sociability and positive emotionality.     

Interplay between environmental and genetic factors in temperament/personality traits in horses (Equus caballus)

The aim of the present study was to broach the question of the relative influence of different genetic and environmental factors on different temperament/personality traits of horses (Equus caballus). The researchers submitted 702 horses to standardized experimental tests and investigated 9 factors, either genetic or environmental. Genetic factors, such as sire or breed, seemed to influence more neophobic reactions, whereas environmental factors, such as the type of work, seemed to play a more dominant role in reactions to social separation or learning abilities. Additive effects were evident, showing how environmental factors may modulate behavioral traits. This study constitutes a first step toward understanding the relative weights of genetic factors and how the environment may intervene in determining individual behavioral characteristics.     

Common genetic influences on impulsivity facets are related to goal management,psychopathology, and personality

In this study, we characterized the genetic/environmental commonality and heterogeneity of impulsivity facets and tested the hypothesis that goal-management is central to their common variance. 764 young-adult twins completed the UPPS-P Impulsive Behavior Scale and measures of goal management, personality, and psychopathology. We found common genetic influences across all impulsivity facets except sensation seeking. These impulsivity genetic influences explained 40.0% of variance in goal-management ability. Other results supported three hypotheses concerning heterogeneity: that sensation seeking is independent of other facets, that urgency is more related to psychopathology than lack of premeditation, and that lack of perseverance is more similar to urgency than lack of premeditation. Thus, impulsivity facets show considerable heterogeneity in addition to common variation related to goal-management abilities.     

Personal goals and personality traits among young adults: Genetic and environmental effects

To assess genetic and environmental contributions to personal goals, 1279 twins aged 20-26 filled in Personal Project Analysis and NEO-FFI inventories. Personal goals relating to education, the respondent’s own family, friends, property, travel and self showed primarily genetic and unique environmental effects, whereas goals related to parents and relatives showed both shared and unique environmental effects. The variation in goals related to health, work, hobbies and life philosophy was attributable to non-shared environmental effects. Openness to experience and personal goals related to family, education and property shared a significant amount of genetic influence. The same was true for extraversion and self-related goals, and agreeableness and goals related to property.     

Genetic and environmental influences on observed personality: evidence from the German Observational Study of Adult Twins

Previous behavior-genetic research on adult personality relied primarily on self-reports or peer reports that may be subject to contrast effects, resulting in biased estimates of genetic and environmental influences. In the German Observational Study of Adult Twins (GOSAT), personality traits of 168 monozygotic (MZ) and 132 dizygotic (DZ) twin pairs were rated on 35 adjective scales, largely markers of the Big 5. The ratings were provided by 120 judges who never met the twins but observed videotaped behaviors of 1 twin of each pair in 1 of 15 different settings. The aggregated video-based trait ratings were highly reliable, and substantial correlations were obtained between MZ as well as DZ twins. Model-fit analyses suggested about 40% genetic, 25% shared environmental, and 35% nonshared environmental influence. Extraversion was the only trait that seemed not to be influenced by shared environment.