Personality and marital satisfaction: a behavioural genetic analysis

A case-control study to differentiate parents' personality traits on anorexia nervosa and affective disorders

Eating disorders (ED) and affective disorders (AD) in adolescent population and several investigations have pointed out that specific family dynamics play a major role in the onset, course, and maintenance of both disorders. The aim of this study was to extend the literature of this topic by exploring differences between parents' personality traits, coping strategies, and expressed emotion comparing groups of adolescents with different mental conditions (anorexia nervosa vs. affective disorder vs. control group) with a case-control study design. A total of 50 mothers and 50 fathers of 50 girls with anorexia nervosa (AN), 40 mothers and 40 fathers of 40 girls with affective disorder (AD), and 50 mothers and 50 fathers of 50 girls with no pathology that conformed the control group (CG) were measured with the Temperament and Character Inventory (TCI), the COPE Inventory, the Family Questionnaire (FQ), and psychopathology variables, anxiety, and depression. Both parents of girls with AN showed a significant difference in personality, coping strategies, and expressed emotion compared to both parents in the CG, while they presented more similarities to parents of girls in the AD group. Identifying personality traits, expressed emotion, coping strategies, and psychopathology of parents and their daughters will allow improvements in the interventions with the adolescents, parents, and families.

Pathology in Relationships

Committed, long-term romantic relationships are ubiquitous among modern society. They are one of the most important contexts for the development, maintenance, and treatment of psychopathology. In this review, I first place psychopathology within the most commonly cited theoretical model of marital satisfaction and stability and then discuss how relationship satisfaction is conceptualized and assessed in this literature. In the second half of the review, I describe the theories regarding how romantic relationships may be connected to psychopathology. Relationship distress is easily incorporated into a diathesis-stress model as an important trigger for psychopathology. Next, I review cross-sectional research, longitudinal research, and treatment efficacy research linking relationship quality and psychopathology. I provide evidence for the robustness of these effects and areas where research must expand. I finish with a summary section that synthesizes what is known about the mechanisms linking relationship distress and psychopathology.

The Role of Emergence in Genetically Informed Relationships Research: A Methodological Analysis

This paper provides a critical analysis of genetically informed research on relationships, with an emphasis on relationships among unrelated individuals (e.g., spouses). To date, research in this area has used traditional behavioral genetic frameworks to either partition the variance in relationship-related outcomes into genetic and environmental components, or to examine gene-environment interplay between relationship factors and other outcomes. However, this conventional approach is at odds with the long-standing understanding from the field of relationship science that both partners' characteristics matter when predicting shared outcomes-that is, outcomes that are emergent. We examine briefly the philosophical concept of emergence, and discuss ways to model dyadic outcomes in genetically informed relationships research. We also review the related topic of social genetic effects, which refer to the influence of a social partner's genotype on a proband's phenotype. A genetically informed dyadic perspective has potentially important consequences for our understanding of the pathways from genotype→shared or individual-level phenotypes, and more fully recognizes the complexity of how genetic and social/environmental factors come together to influence human behavior.

Gene-Environment Interplay in the Context of Romantic Relationships

A growing body of research supports an important role for genetic factors on intimate, romantic relationships. In this article, we review research that has examined the interplay between genetic and environmental influences on romantic relationships and the associations between relationship outcomes and important individual differences related to relationships. We first elaborate on how behavioral genetic and molecular genetic methods can be used to understand the etiology of relationship outcomes. We then review empirical studies that have examined gene-environment correlations and gene-by-environment interactions in predicting romantic relationship outcomes (e.g., relationship formation, relationship quality and functioning, relationship dissolution) and their association with the physical health, mental health, and well-being of relationship partners.

Romantic Relationship Satisfaction Moderates the Etiology of Adult Personality

The heritability of major normative domains of personality is well-established, with approximately half the proportion of variance attributed to genetic differences. In the current study, we examine the possibility of gene × environment interaction (G×E) for adult personality using the environmental context of intimate romantic relationship functioning. Personality and relationship satisfaction are significantly correlated phenotypically, but to date no research has examined how the genetic and environmental components of variance for personality differ as a function of romantic relationship satisfaction. Given the importance of personality for myriad outcomes from work productivity to psychopathology, it is vital to identify variables present in adulthood that may affect the etiology of personality. In the current study, quantitative models of G×E were used to determine whether the genetic and environmental influences on personality differ as a function of relationship satisfaction. We drew from a sample of now-adult twins followed longitudinally from adolescence through age 29. All participants completed the Multidimensional Personality Questionnaire (MPQ) and an abbreviated version of the Dyadic Adjustment Scale. Biometric moderation was found for eight of the eleven MPQ scales examined: well-being, social potency, negative emotionality, alienation, aggression, constraint, traditionalism, and absorption. The pattern of findings differed, suggesting that the ways in which relationship quality moderates the etiology of personality may depend on the personality trait.

Some personality traits converge gradually by long-term partnership through the lifecourse--genetic and environmental structure of Cloninger's temperament and character dimensions

Temperament and Character Inventory (TCI) is a comprehensive personality inventory that is widely used in behavioral genetics. The original theory suggested that temperament traits were under genetic influences, whereas character traits were gradually built by an interaction between temperaments and environment until early adulthood. This study attempted to evaluate TCI by examining the genetic and environmental contributions to personality with particular attention to spousal effects. From 687 families, a total of 3459 Korean adult individuals completed the survey. Among them, there were 542 Monozygotic (MZ) twin pairs and 122 Dizygotic twin pairs. Intraclass correlation coefficients (ICCs) and heritability were calculated to examine the genetic and shared environmental contributions to personality. Moderate genetic contributions (0.17-0.43) were found for all TCI traits along with the evidence of shared environment (0.11-0.31) for harm avoidance (HA) and all characters. The ICCs of TCI in MZ pairs ranged 0.36-0.46. Spouses' had little resemblance for temperament, whereas for character dimensions, spouses (0.27-0.38) were more similar than first degree relatives (0.10-0.29). Resemblance between spouses increased with duration of marriage for most characters and HA. When the growing similarities between spouses were compared with their MZ cotwins' for subgroup of 81 trios, self-directedness (SD) of character showed even more similarities toward their spouses than cotwins as partnership duration increased (r = 0.32). Our findings with regard to change in SD into late adulthood support the psychobiological theory of temperament and character, which suggests that both personality domains have distinct developmental trajectories despite equally large genetic influences.

Can Genetic Factors Explain the Spillover of Warmth and Negativity Across Family Relationships?

Previous studies indicate that the emotional quality of marital relationships is mirrored in parent–child relationships. We explored the degree to which these associations are explained by genetic and environmental factors. Participants were drawn from the Twin and Offspring Study in Sweden (TOSS), and included 544 female twin pairs (258 monozygotic [MZ], 286 dizygotic [DZ]), and 311 male twin pairs (128 MZ, 183 DZ). The spouses and one adolescent child of each twin also participated in this study. The twins completed self-report measures that assessed their marital quality and their warmth and negativity towards their children. Observational ratings of marital warmth and negativity, and of maternal warmth and negativity were obtained for a subset of female twin pairs (150 MZ, 176 DZ). Selfreported marital satisfaction was associated with self-reported parental warmth and negativity for mothers (rs = .25, -.36) and fathers (rs = .25, -.44). For the observational measures, marital warmth was associated with maternal warmth (r = .42), while marital negativity was associated with maternal negativity (r = .34). On average genetic factors explained nearly half of the covariance between selfreported marital satisfaction and parenting for mothers (48%) and fathers (47%). Genetic factors explained 21% of the covariance between observed marital and maternal warmth, but did not contribute to associations between marital and maternal negativity. These findings indicate that parents' genetically influenced characteristics help shape the emotional climate of the family.

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.

Marriage and Divorce: A genetic perspective

Marriage is considered one of the most important sources of social support that an individual receives as an adult. Although hypotheses have been formulated as to why individuals may dissolve a marriage, the determinants of marital success or failure are still relatively unknown. Behavioral geneticists have found that both marriage and divorce are, in part, genetically influenced. The goal of this research was to determine the degree of shared genetic and environmental variance between the two marital statuses. Participants were 6,225 twin pairs from the Vietnam Era Twin Registry. Data were obtained on marital history, and if the individual was no longer married, how the marriage ended. Univariate analyses were performed to determine the extent of genetic and environmental influences each of the marital statues (i.e., marriage and divorce), followed by a novel bivariate analysis to test the shared variance between marriage and divorce. Results from this analysis revealed that the two different marital statuses were influenced by entirely distinct genetic and environmental factors.

Environment, genes, and experience: lessons from behavior genetics

The article reviews the theoretical analysis of the problems inherent in studying the environment within behavior genetics across several periods in the development of environmental studies in behavior genetics and proposes some possible alternatives to traditional approaches to studying the environment in behavior genetics. The first period (from the end of the 1920s to the end of the 1970s), when the environment was not actually studied, is called pre-environmental; during this time, the basic principles and theoretical models of understanding environmental effects in behavior genetics were developed. The second period is characterized by the development of studies on environmental influences within the traditional behavior genetics paradigm; several approaches to studying the environment emerged in behavior genetics during this period, from the beginning of the 1980s until today. At the present time, the field is undergoing paradigmatic changes, concerned with methodology, theory, and mathematical models of genotype-environment interplay; this might be the beginning of a third period of development of environmental studies in behavior genetics. In another part, the methodological problems related to environmental studies in behavior genetics are discussed. Although the methodology used in differential psychology is applicable for assessment of differences between individuals, it is insufficient to explain the sources of these differences. In addition, we stress that psychoanalytic studies of twins and their experiences, initiated in the 1930s and continued episodically until the 1980s, could bring an interesting methodology and contribute to the explanation of puzzling findings from environmental studies of behavior genetics. Finally, we will conclude with implications from the results of environmental studies in behavior genetics, including methodological issues.

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.

The heritability of personality is not always 50%: gene-environment interactions and correlations between personality and parenting

Twin studies of personality are consistent in attributing approximately half of the variance in personality to genetic effects, with the remaining variance attributed to environments that make people within the same families different. Such conclusions, however, are based on quantitative models of human individual differences that estimate genetic and environmental contributions as constants for entire populations. Recent advances in statistical modeling allow for the possibility of estimating genetic and environmental contributions contingent on other variables, allowing the quantification of phenomena that have traditionally been characterized as gene-environment interaction and correlation. We applied these newer models to understand how adolescents' descriptions of their relationships with their parents might change or moderate the impact of genetic and environmental factors on personality. We documented notable moderation in the domains of positive and negative emotionality, with parental relationships acting both to enhance and diminish both genetic and environmental effects. We discuss how genetic and environmental contributions to personality might be more richly conceptualized as dynamic systems of gene-environment interplay--systems that are not captured by classical concepts, such as the overall heritability of personality.

Genetics of personality disorders

This review of the literature on genetic contributions to the etiology of personality disorders broadly follows the DSM classification, and begins by evaluating the current evidence for genetic influences on the DSM axis II disorders. One of the most exciting directions in psychiatric genetics is the rapidly developing field of molecular genetic studies aiming to identify specific genes correlated with psychiatric phenotypes. Personality disorders, like most other psychiatric diagnostic categories, are etiologically complex, which implies that they are influenced by several genes and several environmental factors. The interplay between genes and the environment is a field that is receiving increasing attention and is addressed both in relation to quantitative and molecular methods.

Marital interaction in middle and old age: a predictor of marital satisfaction?

Many studies point out the importance of marital satisfaction for well-being. However, although being married is still the norm in middle and old age, research on the determinants of marital satisfaction has neglected long-term marriages. While research on short-term marriages mainly focuses on partner fit (e.g., in personality traits and socio-economic status), marital interactions should be more important for marital satisfaction in long-term marriages. In this article we examine the role of both stable, dispositional factors and of marital interaction in predicting marital satisfaction in long-term marriages in middle and old age. With data from 588 married women and men in middle and old age who participated in the Interdisciplinary Longitudinal Study of Adult Development (ILSE), we examined age and gender differences in the role of socio-economic status, personality, and marital interaction as predictors of marital satisfaction. Results showed a) that socio-economic factors and personality played a minor role in predicting marital satisfaction, and b) that a high quality of dyadic interaction was particularly important for the marital satisfaction of women. The implications of these findings for future research and interventions on marital interaction in middle and old age are discussed.

Gene-environment correlations: a review of the evidence and implications for prevention of mental illness

Family studies have demonstrated genetic influences on environmental exposure: the phenomenon of gene-environment correlation (rGE). A few molecular genetic studies have confirmed the results, but the identification of rGE in studies that measure genes and environments faces several challenges. Using examples from studies in psychology and psychiatry, we integrate the behavioral and molecular genetic literatures on rGE, describe challenges in identifying rGE and discuss the implications of molecular genetic findings of rGE for future research on gene-environment interplay and for attempts to prevent disease by reducing environmental risk exposure. Genes affect environments indirectly, via behavior and personality characteristics. Associations between individual genetic variants and behaviors are typically small in magnitude, and downstream effects on environmental risk are further attenuated by behavioral mediation. Genotype-environment associations are most likely to be detected when the environment is behaviorally modifiable and highly specified and a plausible mechanism links gene and behavior. rGEs play an important causal role in psychiatric illness. Although research efforts should concentrate on elucidating the genetic underpinnings of behavior rather than the environment itself, the identification of rGE may suggest targets for environmental intervention even in highly heritable disease. Prevention efforts must address the possibility of confounding between rGE and gene-environment interaction (G x E).

Marriage and Genetic Variation across the Lifespan: Not a Steady Relationship?

The prevalence of marriage varies across the lifespan, as does its importance to reproduction and the nurturance of children. We examined genetic and environmental influences on self-reported marriage at each decade from 20 through 70 years of age, using data collected for the Duke Dementia Study, a followed-up subset of the World War II Veteran Twin Registry. Genetic influences best fit a common factor model, supplemented by another, age-specific, genetic factor at age 30. Broad heritability increased from age 20 through 40, and then decreased to zero by ages 60 and 70. A longitudinal Cholesky model best described environmental influences on marriage across the lifespan. Shared environmental factors showed their greatest influence at age 20, no influence at 30 or 40 years, and then, reappeared with influence at 60 and 70. Variance due to error and unique environmental influences increased steadily to age 50 years and then declined slightly.

Genetic strategies for clarifying a nosology of relational distress

The Diagnostic and Statistical Manual of Mental Disorders (4th ed.; American Psychiatric Association, 1994) has made many strides but can be improved with the addition of relationship descriptions. Relational patterns may result from individual genetic risk factors and thus help to define disorders more clearly. Relationships may also mediate genetic risk factors and be useful in identifying the genetic vulnerability, or they may moderate underlying vulnerable genes so that they are less expressed. Key prototypic relationship patterns have inherent interest to humans, moderate numerous illnesses, and deserve attention in and of themselves. Similar to the use of genetic strategies in clarifying taxons of individual disorders, genetic strategies can help delineate patterns within these key relationships, their common origins, their common outcomes, and their distinctions from near-neighbor patterns.