Julie Aitken Schermer

Evidence for a heritable general factor of personality in two studies.

Two studies were conducted to see whether a general factor of personality (GFP) could be extracted from different measures of personality. Using samples of twins in both studies also allowed an assessment of the extent to which genetic and/ or environmental factors contributed to individual differences in the GFPs that were found. In Study 1, principal components analysis of the Big Five personality traits in combination with four scales of mental toughness yielded a strong GFP and behavior genetic model-fitting showed that individual differences in this GFP were fully accounted for by genetic and nonshared environmental factors. In Study 2, a GFP was extracted from the Big Five traits in combination with 15 facets of emotional intelligence. Individual differences in this GFP were also fully accounted for by genetic and nonshared environmental factors. These studies add to the growing body of research demonstrating the existence of a GFP and replicate one previous report of its heritability.

Phenotypic and Genetic Associations between the Big Five and Trait Emotional Intelligence

This study reports the first behavioral genetic investigation of the extent to which genetic and/or environmental factors contribute to the relationship between the Big Five personality factors and trait emotional intelligence. 213 pairs of adult monozygotic twins and 103 pairs of same-sex dizygotic twins completed the NEO-PI-R and the Trait Emotional Intelligence Questionnaire (TEIQue). Replicating previous non-twin studies, many significant phenotypic correlations were found between the Big Five factors - especially Neuroticism, Extraversion, and Conscientiousness - and the facets, factors, and global scores derived from the TEIQue. Bivariate behavioral genetic model-fitting analyses revealed that these phenotypic correlations were primarily attributable to correlated genetic factors and secondarily to correlated non-shared environmental factors. The results support the feasibility of incorporating EI as a trait within existing personality taxonomies.

A general factor of personality: evidence from the HEXACO model and a measure of trait emotional intelligence.

The purpose of the present study was to determine if a general factor of personality (GFP) could be extracted from the six dimensions of the HEXACO model and four factors of trait emotional intelligence. Participants were 1,192 pairs of twins (666 MZ pairs, 526 DZ pairs) between the ages of 19 to 86 years, who completed the Trait Emotional Intelligence Questionnaire - Short Form and the HEXACO Personality Inventory - Revised. Principal components analysis yielded a strong GFP accounting for 33% of the variance, on which all variables with the exception of honesty-humility from the HEXACO showed moderate to large loadings. Behavioral genetic (BG) analyses revealed that individual differences in the GFP were entirely attributable to additive genetic and non-shared environmental factors - results that are in accord with previous BG analyses of a GFP. The present study adds to the body of evidence in support of a heritable GFP but an alternative perspective is also discussed.

A Behavioral Genetic Study of Trait Emotional Intelligence

Numerous models of emotional intelligence (EI) have proposed the existence of hitherto undiscovered mental abilities, competencies, and skills. The theory of trait emotional intelligence suggests that the content domains of these models invariably contain permutations of personality traits. The two studies in this article examine the heritability of trait EI scores with a view to demonstrating empirically that the construct has a similar level of genetic influence as other personality traits. Study 1 was a family design of 133 high-school students and their parents. Regressions of offspring on midparent scores suggested median upper-limit heritability estimates of .18 at facet level, .25 at factor level, and .32 at the global trait EI level. Study 2 was a twin design (213 pairs of monozygotic [MZ] twins and 103 pairs of dizygotic [DZ] twins). It yielded median heritabilities of .42 for the facets, .44 for the factors, and .42 for global trait EI. Overall, our findings are in accordance with studies of the major personality dimensions and provide further empirical support for the conceptualization of EI as a personality trait.

A Behavioral Genetic Study of the Dark Triad of Personality and Moral Development

The present study is the first behavioral genetic investigation of relationships between the Dark Triad of personality--Machiavellianism, narcissism, and subclinical psychopathy--and moral development. Participants were 154 monozygotic twin pairs and 82 same-sex dizygotic twin pairs. Higher scores on Machiavellianism and psychopathy were positively correlated with low levels of moral development; high psychopathy scores also correlated negatively with high levels of moral development. Individual differences in lower levels of moral development were attributable to genetic and nonshared environmental factors but, very interestingly, individual differences in the highest levels of moral development showed no genetic basis but were entirely attributable to shared and nonshared environmental factors. Finally, correlations between the Dark Triad and moral development variables showed no genetic basis while correlations among the moral development variables were variously attributable to correlated genetic and correlated environmental factors.

Phenotypic, genetic and environmental properties of the portrait values questionnaire.

The purpose of the present study was to examine the 10 value types from the Portrait Values Questionnaire (PVQ; Schwartz et al., 2001) both at the phenotypic (observed) level as well as the genetic and environmental level. Australian twins (N = 695) completed the PVQ as part of a larger questionnaire battery. Nine of the value types were found to have a genetic component with heritability estimates ranging from 10.8% for power to 38% for conformity. The achievement scale was best explained by environmental factors. The interscale correlations were found to range from -.02 to .70 at the phenotypic level. Of these 45 correlations, 16 were found to be explained by overlapping genetic factors and almost all (41) were found to have significant unique environment correlations.

Genetic and Environmental Correlations Between Trait Emotional Intelligence and Humor Styles

This article reports the first studies to investigate the genetic and environmental components of correlations between humor styles and trait emotional intelligence. In two independent adult-twin samples, significant phenotypic correlations were found between four humor styles (affiliative, self-enhancing, aggressive, and self-defeating) and five trait emotional intelligence (EI) variables (well-being, self-control, emotionality, sociability, and global trait EI). These observed phenotypic correlations were themselves found to be largely attributable to correlated genetic and correlated nonshared environmental factors.

Overlap between the general factor of personality and emotional intelligence: A meta-analysis.

We examine the relationship between the general factor of personality (GFP) and emotional intelligence (EI) and specifically test the hypothesis that the GFP is a social effectiveness factor overlapping conceptually with EI. Presented is an extensive meta-analysis in which the associations between the GFP, extracted from the Big Five dimensions, with various EI measures is examined. Based on a total sample of k = 142 data sources (N = 36,268) the 2 major findings from the meta-analysis were (a) a large overlap between the GFP and trait EI (r ≈ .85); and (b) a positive, but more moderate, correlation with ability EI (r ≈ .28). These findings show that high-GFP individuals score higher on trait and ability EI, supporting the notion that the GFP is a social effectiveness factor. The findings also suggest that the GFP is very similar, perhaps even synonymous, to trait EI.

A behavior genetic study of the connection between social values and personality.

The present research examined the extent to which relations between social values and personality are due to shared genetic or environmental factors. Using the Rokeach (1973) Value Survey and a scoring key from Schwartz and Bilsky (1990), seven value scores (enjoyment, achievement, self-direction, maturity, prosocial, security, and restrictive conformity) were derived in a sample of twins. As expected, all of the value scales were found to have a significant genetic component, with values ranging from 36% for enjoyment to 63% for prosocial, and there were numerous significant phenotypic correlations found between the value scales and personality scores. Most important, bivariate genetic analyses revealed that some of these phenotypic correlations could be attributed to common genetic or environmental factors.

Genetic and Environmental Contributions to Humor Styles: A Replication Study

One thousand and seventy three pairs of adult monozygotic (MZ) twins and 895 pairs of same sex adult dizygotic (DZ) twins from the United Kingdom (UK) completed the Humor Styles Questionnaire: a 32-item measure which assesses two positive and two negative styles of humor. MZ correlations were approximately twice as large as DZ correlations for all four humor styles, and univariate behavioral genetic model fitting indicated that individual differences in all of them can be accounted for entirely by genetic and nonshared environmental factors, with heritabilities ranging from .34 to .49. These results, while perhaps not surprising, are somewhat at odds with a previous study that we conducted in North America (Vernon et al., in press) in which genetic factors contributed significantly to individual differences in the two positive humor styles, but contributed far less to the two negative styles, variance in which was instead largely due to shared and nonshared environmental factors. We suggest that differences between North American and UK citizens in their appreciation of different kinds of humor may be responsible for the different results obtained in these two studies.