Abstract
Research on the Dark Triad traits—psychopathy, Machiavellianism, and narcissism—reveals malevolent, transgressive, and self-centered aspects of personality. Little is known about the Dark Triad traits in individuals differing in sexual orientation, with some studies showing that non-heterosexual individuals have Dark Triad profiles resembling those of opposite-sex heterosexual individuals. In a cross-national sample (N = 4063; 1507 men, 2556 women; Mage = 24.78, SDage = 7.55; 90.58% heterosexual, 5.74% bisexual, 2.83% homosexual) collected online via student and snowball sampling, we found in sex-aggregated analyses that bisexuals and homosexuals were more Machiavellian than heterosexuals. Bisexuals were more psychopathic and narcissistic than heterosexuals. The only significant findings in within-sex comparisons showed that self-identified bisexual women scored higher on all Dark Triad traits than heterosexual women. The findings support the gender shift hypothesis of same-sex sexual attraction in bisexual women, but not in lesbians nor in men. The finding that bisexuals are the sexual orientation group with the most pronounced Dark Triad profiles is opposite to what would be predicted by the prosociality hypothesis of same-sex sexual attraction. The life history and minority stress implications of these findings are discussed as alternative hypotheses to the gender shift hypothesis.Introduction
Psychological and behavioral differences between the sexes have been studied scientifically for more than a century (Archer, 2019; Darwin, 1871; Woolley, 1910). As findings on sex differences have accumulated over time, the way in which non-heterosexual individuals may differ from heterosexuals on a range of psychobehavioral traits has received increasing attention (Allen & Robson, 2020; Luoto, 2021a; Zheng et al., 2011), as have the evolutionary–developmental mechanisms that create sex differences (Archer, 2019; Luoto & Varella, 2021) and sexual orientation differences (Luoto, 2020a; Luoto et al., 2019a, Luoto et al., 2019b; Rahman & Wilson, 2003) in such psychobehavioral traits.Sexual differentiation of the mammalian brain constitutes an integral evolutionary–developmental process which causes a cascade of sexually differentiated outcomes in men and women, ranging from physiological, cognitive, and behavioral traits to different life outcomes, for instance, in health and in educational and professional trajectories (Archer, 2019; Luoto, 2020b; Luoto et al., 2019a, Luoto et al., 2019b; Luoto & Varella, 2021; Mauvais-Jarvis et al., 2020; McCarthy, 2020; Luoto et al., 2021). Developmental disturbances in the sexual differentiation of the brain may result in various kinds of non-heterosexual phenotypes, which show sex-atypicality across a range of biobehavioral traits (Luoto, 2021a; Luoto et al., 2019a, Luoto et al., 2019b; Rahman & Wilson, 2003; Swift-Gallant et al., 2019). One conceptualization of personality traits is that they are behavioral syndromes (e.g., complexes of correlated behaviors creating patterns) as opposed to internal traits, and as such, might also be subject to such differentiation (Woodley of Menie et al., 2021). Given that sexuality and sexual orientation are characterized by specific behaviors, and behaviors are related to personality traits, understanding how personality traits relate to various manifestations of sexuality seems warranted (Lippa, 2020; Luoto et al., 2019a; Luoto, 2021a).
One potential hypothesis for explaining the opposite-sex shift observed in non-heterosexual individuals' psychobehavioral and morphological traits is the gender shift hypothesis, which posits that homosexual and bisexual men are partially feminized and homosexual and bisexual women are partially masculinized on several psychobehavioral and morphological traits (Bailey et al., 2016; Luoto et al., 2019a; Luoto, 2021a). The gender shift hypothesis assumes that the effective sexuality phenotype (1) has been ancestrally calibrated to increase inclusive fitness but (2) developmental disturbances may occur in this sexually differentiated process, creating phenotypes that may diverge from sex-specific optima. Natural variation in neurodevelopmental processes may lead to sex-atypical behaviors and attitudes (e.g., sexual desire, sexual orientation, and personality) as in the case of non-heterosexual men and women. This hypothesis has received broad though not fully clear support across several studies (Abé et al., 2021; Lippa, 2020; Luoto, 2020a; Luoto et al., 2019a; Luoto, 2021a; Rahman & Wilson, 2003; Schmitt, 2006). Moreover, bisexual men and women tend to show gender nonconformity and cross-sex neuroanatomical changes which place them between heterosexual and homosexual participants (Abé et al., 2021; Rieger et al., 2020). On other psychobehavioral traits, such as neuroticism, extraversion, and agreeableness, bisexual women tend to be more masculine than heterosexual women; with traits such as sex drive, sociosexuality, conscientiousness, and openness to experience, bisexual women tend to be even more masculine than lesbian women (Luoto & Rantala, in press). Bisexual men had higher sex drive, sociosexuality, openness to experience, and neuroticism and lower conscientiousness than heterosexual men (Lippa, 2020; Schmitt, 2006), only partially supporting the gender shift hypothesis. In this article, we sought to test the gender shift hypothesis using the Dark Triad traits in men and women differing in (self-reported) sexual orientation (i.e., heterosexual, bisexual, homosexual).
The Dark Triad traits (i.e., narcissism, Machiavellianism, and psychopathy) are “darker” sides of personality; yet despite being sometimes viewed as harmful for individuals and groups, they can in fact be adaptive (Furnham et al., 2013; Koehn et al., 2019). Narcissistic people have a sense of grandiosity, egotism, and self-orientation; Machiavellian individuals are often manipulative and exploitative, with a ruthless lack of morality; and psychopathic people engage in antisocial behavior, are impulsive, and lack empathy and remorse. The traits may enable fast life history strategies that allow people to pursue selfish social and sexual agendas that impose costs on those around them (e.g., Jonason et al., 2017). Life history theory suggests that organisms have a finite amount of resources to solve the adaptive problems of mating and surviving, and the way organisms navigate such resource-allocation decisions is by trading off one goal for another. Those who prioritize survival over mating are r-selected or fast life history strategists whereas those who prioritize mating over survival and/or development are K-selected or slow life history strategists. Fast, as opposed to slow, life history strategies at the species level translate to faster maturation, more mortality, and less investment in offspring (e.g., elephants are slow; mice are fast). At the within-species level (cf. Woodley of Menie et al., 2021), fast life history traits can include promiscuity, risk-taking, aggression, and limited empathy, all of which are heightened in those characterized (with some contextual modification at times) by the Dark Triad traits (Jonason et al., 2017; Koehn et al., 2019; Luoto et al., 2019a).
The Dark Triad traits comprise an interesting test case for analyzing psychological differences across the sexual orientation spectrum because of their heritability and the reported sex differences in the traits. The Dark Triad traits reveal small (Cohen's d ≈ 0.20) to large (d ≈ 0.70) sex differences cross-nationally (Jonason et al., 2013; Jonason, Żemojtel-Piotrowska, et al., 2020). Social role (e.g., social learning, structural powerlessness) and evolutionary (e.g., sexual selection, parental investment, and life history theory) models provide explanations for these sex differences (e.g., Archer, 2019; Luoto et al., 2019a). For instance, researchers relying on the former model might suggest that women may be punished more for these traits; therefore, women suppress their “bad” behaviors more than men do. Alternatively, ancestral men may have reaped reproductive fitness benefits for being “bad”, leading to differences in the sexes that persist to this day. For instance, men may accrue more sex partners while women may be more likely to suffer from reproductive health problems for having more pronounced Dark Triad traits and associated behaviors (Jonason et al., 2009; Jonason & Lavertu, 2017). While evolutionary models of sex differences writ large (Archer, 2019; Luoto & Varella, 2021) and in the Dark Triad traits (Jonason, Żemojtel-Piotrowska, et al., 2020) might be superior in accounting for these differences than social constructionist accounts (Luoto et al., 2019a), the two should not be seen as completely in conflict given that they are concerned with proximate (e.g., how) and ultimate (e.g., why) questions. For instance, the adaptive utility of pursuing particular life history strategies describes effects originating both in the past and the current environments, whereas sex-specific norms describe how people learn and calibrate their behaviors to fit their current social contexts. That is, instead of a blank slate hypothesis (i.e., environmental determinism), as often relied on by social constructivists, an evolutionary account can merge ancestrally derived predispositions and biases with current conditions and needs. Evolutionary approaches are therefore inherently interactionist, not genetically deterministic, focusing as they do on the proximate (neuro)developmental and other biopsychosocial mechanisms underlying sex differences and sexual orientation differences (Luoto et al., 2019a; Luoto & Varella, 2021).
Despite the popularity of research on the Dark Triad traits in the context of sex differences and sexual behavior, few studies have examined whether there are differences in the Dark Triad traits between people of different sexual orientations. This may be related to limited access to enough non-heterosexual individuals in convenience samples and a lack of hypotheses about why there might be any sexual orientation differences. We acknowledge the third possibility that researchers may have avoided asking this question because of fears of the results being misinterpreted as portraying non-heterosexuals in a negative light. Two studies (we know of) on sexual orientation differences in Dark Triad traits have found that bisexual women scored higher on the Dark Triad traits than heterosexual women or lesbians (Semenyna et al., 2018; Stolarski et al., 2017). These findings conform to a broader pattern of psychological masculinization in non-heterosexual women across a variety of personality measures (Luoto et al., 2019a, Luoto et al., 2019b; Luoto, 2021a). Besides these results in women, we are unaware of any studies that have analyzed the Dark Triad traits across the sexual orientation spectrum (i.e., including bisexual men, and ideally also “mostly heterosexual” individuals). In one study, homosexual men scored lower on Machiavellianism (d = 0.11), narcissism (d = 0.17), and psychopathy (d = 0.42) relative to heterosexual men (Barelds et al., 2017). In women, the only difference of note was the slightly higher psychopathy scores in homosexual women (d = 0.15) relative to heterosexual women (Barelds et al., 2017).1 Overall, these results support the gender shift hypothesis of homosexuality.
In this study, we sought to test the gender shift hypothesis of homosexuality in a cross-national sample which, unlike previous studies, also included bisexual males. Based on prior theoretical and empirical work (Lippa, 2020; Luoto, 2020a; Luoto et al., 2019a), we predicted that non-heterosexual women would score higher (more male-typical) on the Dark Triad traits than heterosexual women. We extended the gender shift hypothesis (Luoto, 2020a; Luoto, 2021a) to men and predicted that non-heterosexual men would score lower (more female-typical) on the Dark Triad traits relative to heterosexual men. In addition, we provide a novel test of a new and potentially problematic (Luoto, 2020a) suggestion—which appears to originate from work on Bonobos (Pan paniscus)—suggesting homosexuality may have evolved as part of increased prosociality (Barron & Hare, 2020).
Section snippets
Participants and procedures
In 2014, an international team of researchers collected self-report data2 from 42 countries online in English or a local language (e.g., French) from 4063 people (2556 female, 1507 male) who received course credit or were volunteers, aged 18 to 69 years old (M = 24.78, SD = 7.55).3Results
We refrained from testing a full ANOVA model because of sample size concerns and instead relied on planned comparisons with t-tests and one-way ANOVAs with Scheffe's post-hoc tests, which adjust significance levels to account for multiple comparisons. In Table 1 we summarize F-tests to understand the correlations between sexual orientation and the Dark Triad traits overall (Fig. 1). In sex-aggregated analyses, we found that bisexuals (p = .008, d = 0.21) and homosexuals (p = .007, d = 0.29)Discussion
Overall, we revealed that rates of the Dark Triad traits differed in people who had different sexual orientations, a topic that has rarely been considered in prior research. Our findings suggest that including non-heterosexual men and women in aggregated sex difference analyses may suppress sex differences in traits because non-heterosexual individuals—women in particular—have gender-atypical scores on several of these measures. Conducting analyses with all sexual orientations included mayLimitations and conclusions
The limitations of this study include the relatively small samples of non-heterosexual participants, which attenuated our ability to reliably detect smaller sexual orientation differences. Nevertheless, the proportions of bisexuals and homosexuals in our sample are relatively high given the usually reported prevalence of bisexuality and homosexuality, which indicate that a total of approximately 3.5% of U.S. adults identify as gay, lesbian, or bisexual (Bailey et al., 2016). The relativelyCredit authorship contribution statement
JONASON primarily served as the data manager and analyst, secondarily he authored the Results, and tertiarily served as an author whereas LUOTO was the primary author of the Introduction/Discussion and worked secondarily on analyses.Acknowledgements
The first author was partially funded by the Polish National Agency for Academic Exchange (PPN/ULM/2019/1/00019/U/00001) and a grant from the National Science Centre of Poland (2019/35/B/HS6/00682).Full study attached below.
