بررسی ژنتیکی رفتاری از سه گانه تاریک و پنج عامل بزرگ

This study reports the first behavioral genetic investigation of the three Dark Triad variables (narcissism, Machiavellianism, and psychopathy) and their relationships with the Big 5 personality traits. A total of 278 adult twins completed questionnaire measures of the Dark Triad and the Big 5. Consistent with some previous studies, we found significant correlations among some of the Dark Triad variables and between each of the Dark Triad variables and some of the Big 5. To the extent that these variables were correlated at the phenotypic level, these correlations were largely attributable to correlated genetic factors. At the univariate level, all traits showed the influence of genetic and non-shared environmental factors, with heritabilities ranging between .31 and .72; Machiavellianism alone also showed the influence of shared environmental factors.

The Dark Triad is a relatively recently identified cluster of three personality traits: narcissism, Machiavellianism, and sub-clinical psychopathy (Paulhus & Williams, 2002). A narcissistic personality is characterized by an excessive love for one’s self, feelings of superiority, attention seeking, and exploitativeness in relationships with others. Narcissism has primarily been studied as an abnormal personality disorder, but can also be seen as a normal aspect of personality including ideals of dominance, exploitation and feelings of entitlement (Lee & Ashton, 2005). Machiavellianism includes cold and manipulative behaviors along with insincerity and callousness. Those who score high on Machiavellianism scales tend to employ deception and manipulation for self-benefit (Jakobwitz & Egan, 2006). Psychopathy refers to a sense of high impulsivity, low remorse, and thrill-seeking (Paulhus & Williams, 2002). Like narcissism, psychopathy can be viewed from both a clinical and a non-clinical perspective. The Dark Triad of personality deals with these traits at a sub-clinical level that varies within the normal population. Previous research has demonstrated that these three traits have low to moderate correlations with one another (Jakobwitz & Egan, 2006, Lee & Ashton, 2005 and Paulhus & Williams, 2002). Correlations have also been reported between the Dark Triad and the Big 5 variables, although results have been inconsistent. Paulhus and Williams (2002), for example, reported that narcissism correlated positively with extraversion (r = .42) and openness (r = .38) and negatively with agreeableness (r = −.36); that Machiavellianism correlated negatively with agreeableness (r = −.47) and conscientiousness (r = −.34); and that psychopathy correlated with all Big 5 variables: extraversion (r = .34), agreeableness (r = −.25), conscientiousness (r = −.24), neuroticism (r = −.34) and openness (r = .24). Lee and Ashton (2005) reported similar correlations but Jakobwitz and Egan (2006) found no significant correlations between the Dark Triad and either openness or extraversion. The present study was designed to further explore relationships between the Dark Triad and the Big 5; moreover, by employing samples of twins we can estimate the extent to which any phenotypic correlations that we find between the Dark Triad and the Big 5 are attributable to correlated genetic and/or correlated environmental factors. Numerous previous behavior genetic studies have examined the extent to which individual differences in the Big 5 are attributable to genetic and/or environmental factors. A recent review by Johnson, Vernon, and Feiler (in press), for example, summarized the results of 145 studies conducted between 1955 and 2007 which themselves reported twin and other kinship correlations, and heritability and environmentality estimates for the Big 5 and related traits, from a total of some 240,000 pairs of subjects. The evidence summarized by Johnson et al. (in press) overwhelmingly supports the conclusion that genetic and non-shared environmental factors account for the great majority of the variance, with heritabilities averaging about .45. To our knowledge, no previous behavior genetic studies have been performed on the Dark Triad per se although a number of studies have reported the influence of genetic factors on psychopathy ( Blonigen et al., 2006, Larsson et al., 2006 and Taylor et al., 2003) and on narcissism ( Livesley, Jang, Jackson, & Vernon, 1993). Another goal of the present study is to obtain twin correlations and to estimate heritability and environmentality coefficients for all three Dark Triad variables. We expect that we will replicate previous findings of the influence of genetic factors on psychopathy and narcissism and, based on previous research with other personality traits, we expect also to find a heritable component to Machiavellianism.