Sex and Sexual Orientation Differences in Dark Triad Traits, Sexual Excitation/Inhibition, and Sociosexuality.

The present study sought to investigate sex and sexual orientation differences in several traits related to sexuality and sexual behavior. Examining sexual orientation differences alongside basic sex differences to help identify correlates of sexual orientation diversity, and whether individuals with varying degrees of same-sex attraction show concurrent sex-atypical shifts in other domains. Males tend to score higher than females in the Dark Triad (DT) traits of sub-clinical narcissism, psychopathy, and Machiavellianism. Similarly, females tend to be more cautious than males in their attitudes and desires toward casual sex activity (i.e., sociosexuality). These sex differences may be related to the propensity for individuals to become easily sexually excited, which is higher in males, or to instead inhibit sexual arousal, which is higher in females. In a large undergraduate sample (N = 2047), we replicated expected sex differences in DT traits, sociosexuality, and sexual excitation/inhibition. We found that non-heterosexual females were "male-shifted" in some of these traits, but these shifts tended to be strongest among mostly heterosexual and bisexual individuals. Furthermore, we found that within-sex variation in sociosexuality, sexual excitation, and sexual inhibition was not related to sexual orientation in a linear fashion. Instead, sociosexuality and sexual excitation were related to sexual orientation in a curvilinear (inverted-U) fashion, especially among females. The fact that traits correlated with bisexuality and homosexuality were somewhat distinct is consistent with the idea that different developmental pathways may lead to these discrete sexual attraction patterns.

Association of Recalled Childhood Sex-Typed Behavior with Sexual Orientation and Gender Identity in Iranian Adult Males and Females.

Same-sex sexual attraction in both males and females has been associated with childhood sex-atypical behavior. Gynephilic females recall behaving in a manner that is less female-typical and more male-typical compared to cisgender androphilic females, whereas androphilic males recall behaving in a manner that is less male-typical and more female-typical compared to cisgender gynephilic males. In addition, male and female ambiphilic individuals exhibit intermediate levels of childhood sex-atypicality. In this study, we examined recalled childhood sex-typed behavior among Iranian cisgender gynephilic males (n = 236), cisgender ambiphilic males (n = 51), cisgender androphilic males (n = 191), transgender androphilic males (n = 60), cisgender androphilic females (n = 243), cisgender ambiphilic females (n = 96), cisgender gynephilic females (n = 32), and transgender gynephilic females (n = 122). Both cisgender androphilic males and cisgender gynephilic females recalled elevated childhood sex-atypicality, scoring intermediate between cisgender gynephilic males and cisgender androphilic females. Male and female ambiphilic participants scored intermediate between their other- and same-sex attracted cisgender counterparts. Transgender androphilic males exhibited hyper-feminized childhood behavior, scoring even more female-typical than cisgender androphilic females. Transgender gynephilic females recalled behaving as male-typical as cisgender gynephilic males. Consistent with previous research, our findings from Iran - a non-Western, Middle Eastern culture - provide cross-cultural support for the universality of childhood sex-atypicality as a normative developmental precursor of monosexual or ambisexual same-sex attraction in both males and females who are cisgender and transgender.

Occupational Preferences, Childhood Behavior, and Openness: The Role of Sex, Sexual Orientation, and Gender Identity in Iran.

Previous research suggests that both same-sex attraction and the personality trait "openness" are associated with sex-atypical preferences and behaviors. Here, we examined the links between adulthood occupational preferences, childhood play behavior, and openness among Iranian cisgender gynephilic males (n = 228), cisgender ambiphilic males (n = 48), cisgender androphilic males (n = 178), transgender androphilic males (n = 58), cisgender androphilic females (n = 226), cisgender ambiphilic females (n = 94), cisgender gynephilic females (n = 31), and transgender gynephilic females (n = 121) from Iran. Cisgender and transgender same-sex attracted males and females exhibited sex-atypical occupational preferences with the latter group showing even more sex-atypicality than the former. The personality trait openness did not differ between cisgender groups. Transgender androphilic males had a significantly higher mean score for openness compared to cisgender androphilic females and transgender gynephilic females, whereas transgender gynephilic females had a significantly lower mean score compared to cisgender androphilic males. In both males and females, childhood sex-atypicality, same-sex attraction, and openness were associated with sex-atypical occupational preferences. Our findings from Iran provides cross-cultural support for interconnectedness of childhood and adulthood sex-atypicality, openness, and same-sex attraction in males and females who are cisgender and transgender.

Inter-sexual Mate Competition in Humans: A Historical Example from Seventeenth Century Portugal.

Inter-sexual mate competition occurs any time opposite-sex individuals simultaneously seek to acquire or maintain exclusive access to the same sexual partner. This underappreciated form of mate competition has been anecdotally documented in several avian and mammalian species, and systematically described among Japanese macaques and humans. Here, we extend the concept of inter-sexual mate competition by reassessing a remarkable series of Portuguese letters, penned in 1664 and later discovered and translated by Mott and Assunção (J Homosex 16:91-104, 1989). The letters comprise one side of a correspondence between two males, former lovers who were scrutinized by the Portuguese Inquisition. After ending the relationship, the recipient of the letters was betrothed to a woman, which provoked a jealous response from his jilted male lover and pleas to reunite. We argue that the letters portray a prolonged sequence of inter-sexual mate competition in which a male and female competitor vied for the same man. An established taxonomy of mate competition tactics was applied to the behavior of both competitors illustrating many parallels with contemporary examples of inter-sexual mate competition. Through this comparison, we show that modern mate competition taxonomies can be fruitfully applied to historical texts and that inter-sexual mate competition occurred hundreds of years before the present. Other examples of inter-sexual mate competition are likely to exist in the historical record, providing a rich source of scientific information if appropriate theoretical frameworks are employed. Indeed, any time individuals are attracted to sexual partners who behave in a bisexual manner, then inter-sexual mate competition can ensue with members of the other sex.

Male androphilia, fraternal birth order, and female fecundity in Samoa: A 10-y retrospective.

Two separate but related literatures have examined familial correlates of male androphilia (i.e., sexual attraction and arousal to masculine adult males). The fraternal birth order effect (FBOE) is a widely established finding that each biological older brother a male has increased the probability of androphilia 20-35% above baseline rates. Other family demographic variables, such as reproduction by mothers, maternal aunts, and grandmothers, have been used to test evolutionary hypotheses that sexually antagonistic genes lead to androphilia among males, lowering or eliminating reproduction, which is offset by greater reproductive output among their female relatives. These proposed female fecundity effects (FFEs), and the FBOE, have historically been treated as separate yet complementary ways to understand the development and evolution of male androphilia. However, this approach ignores a vital confound within the data. The high overall reproductive output indicative of an FFE results in similar statistical patterns as the FBOE, wherein women with high reproductive output subsequently produce later-born androphilic sons. Thus, examination of the FBOE requires analytic approaches capable of controlling for the FFE, and vice-versa. Here, we present data simultaneously examining the FBOE and FFE for male androphilia in a large dataset collected in Samoa across 10 y of fieldwork, which only shows evidence of the FBOE.

Heterosexual Men's Visual Attention to Nude Images Depicting Cisgender Males, Cisgender Females, and Gynandromorphs.

Gynandromorphophilia refers to sexual attraction and arousal to feminine males, who may or may not have breasts, and who retain their penises. Previous research has suggested that some capacity for gynandromorphophilia may characterize males who are gynephilic (i.e., sexually attracted and aroused to adult females). This study examined Canadian cisgender gynephilic men's (n = 65) visual attention and subjective ratings of sexual arousal when presented with nude images of feminine males with, and without breasts, masculine males, and feminine females. Visual attention was assessed using an infrared eye-tracker. Subjective arousal to feminine females was highest, followed by subjective arousal to feminine males with breasts, feminine males without breasts, and masculine males. However, subjective arousal to feminine males without breasts and to masculine males did not differ significantly. The patterning of visual attention to images of females was unique, in that participants were equally likely to attend first to the face, chest or genitals. These areas also elicited relatively greater fixation durations and counts. Although participants fixated onto the chests of feminine males with breasts for longer durations than those of masculine males, most of the differences between feminine males, with and without breasts, were non-significant. These results suggest that female sex-based traits play a more primary role in gynephilic men's sexual arousal than feminine gender-based traits.

Heterosexual men's pupillary responses to stimuli depicting cisgender males, cisgender females, and gynandromorphs.

Gynandromorphophilia is the sexual attraction and arousal to feminine individuals assigned male at birth, who may or may not have breasts, and who retain their penises. Previous research has suggested that some capacity for gynandromorphophilia may characterize all males who are gynephilic (i.e., sexually attracted and aroused to adult cisgender females). This study examined Canadian cisgender gynephilic men's (n = 65) pupillary responses and subjective ratings of sexual arousal when presented with nude images of cisgender males, cisgender females, and gynandromorphs with, and without, breasts. Subjective arousal to cisgender females was highest, followed by subjective arousal to gynandromorphs with breasts, gynandromorphs without breasts and cisgender males. However, subjective arousal to gynandromorphs without breasts and to cisgender males did not differ significantly. Participants' pupils dilated more to images of cisgender females than to all other stimulus categories. Participants' pupils dilated more to gynandromorphs with breasts than to cisgender males, but pupillary response to gynandromorphs without breasts and cisgender males did not differ significantly. If the capacity for gynandromorphophilic attraction is a cross-culturally invariant aspect of male gynephilia, then these data suggest that this capacity may only extend to gynandromorphs with breasts and not gynandromorphs without breasts.

Intra- and Intersexual Mate Competition in Two Cultures : A Comparison of Women's Response to Mate Competition with Women and Gender-Nonbinary Males in Samoa and among the Istmo Zapotec.

The present study examined women's mate competition tactics in response to female and feminine-male rivals in two cultures in which competition against both occurs. In Samoa and the Istmo Zapotec (Southern Mexico), women not only compete with other women (intrasexually) but also compete with rival feminine males (intersexually) in order to access/retain the same masculine men as sexual/romantic partners. Using a mixed-method paradigm, women were asked about their experiences of intra- and intersexual mate competition, and these narratives were recorded. The tactics reportedly employed by participants, and those attributed to mate competitors, were categorized according to established taxonomies of mate competition tactics, and their frequencies compared. Within-culture, the likelihood that participant women had ever experienced intra- and intersexual mate competition did not differ. Furthermore, participants reported a similar pattern of behavioral tactics whether their rival was another woman or a feminine male. These included benefit provisioning tactics during mate acquisition and cost-inflicting tactics during mate retention. Similarly, the mate competition tactics attributed to rival women and rival feminine males bore a striking resemblance, focused on enticing target men. Results highlight the mate competition tactics employed by women outside of a Euro-American context, and the way cultural factors impact mating landscapes presumed to be exclusively heterosexual. The presence of feminine males, alongside masculine men's willingness to engage in sexual activity with them, induces women in such cultures to compete intersexually in comparable ways to intrasexual competition with rival women.

Fertility Status Does Not Facilitate Women's Judgment of Male Sexual Orientation.

Previous research has demonstrated that women can correctly distinguish between gay and heterosexual men's faces significantly better than chance. This ability appears to be heightened during the most fertile portion of their ovulatory cycle. Here, we sought to replicate and extend these findings in a large sample of undergraduate women (N = 1960). Although women correctly identified men's sexual orientation significantly better than chance (62% average accuracy), a subsample of naturally cycling women (n = 426) did not judge men's sexual orientation from faces more accurately when in the fertile phase of their ovulatory cycle. These results further replicate the visibility of male sexual orientation, but do not show that this ability has strong links to estimated fertility.

When males have females on their backs: Male's tolerance, solicitation, and use of female-male mounting in Japanese macaques.

Previous research on Japanese macaques has shown that female-to-male mounting (FMM) is performed by some females as an exaggerated form of sexual solicitation that may occur in the context of high female competition for male mates. This supernormal courtship behavior functions to prompt subsequent male-to-female mounting. In this report, we focused on the male consort partners' responses to FMM. We studied a free-ranging population of Japanese macaques at Arashiyama, Japan, in which FMM is frequent and prevalent. We analyzed 240 consortships involving 31 females and 19 males. We tested three hypotheses regarding male's tolerance, solicitation, and use of FMM. First, we found that FMM was tolerated by male mountees who were no more likely to aggress their female partners during a short time window around a FMM than they were during the rest of the consortship period. Second, we showed that FMM could be triggered by male recipients, via explicit male-to-female sexual solicitations. Third, we found that some males may utilize FMM in a quest for their own sexual stimulation, which sometimes culminated in masturbation by the male during FMM. Our findings indicate that male partners facilitate the expression of FMM both passively (via their tolerance) and actively (via their solicitation). In addition, FMM appears to enhance the sexual arousal of male partners during consortships. We argued that, for females to have expanded their repertoire of sexual solicitations by adopting FMM, male mates must have played a role in the evolutionary origins and maintenance of this nonconceptive but intense and powerful female mating tactic.

Confounds, Causality, and Sexual Orientation: The Implications of a Population-Level Study of Sibling Characteristics and Same-Sex Attraction.

Representative samples, and especially population samples, are coveted sources of high-quality data in psychological science. In their recent article, Ablaza et al. (2021) used a population sample of marriages and registered partnerships in the Netherlands to examine the relationships between sibling characteristics and sexual orientation. We discuss the implications of this work for understanding the fraternal and sororal birth order effects on male and female same-sex attraction, and how both relate to maternal reproduction. The causal assumptions of these findings are explored, as well as the necessity of population-level data, and whether the data presented by Ablaza et al. are truly representative of the Dutch population.

Men's Sexual Interest in Feminine Trans Individuals across Cultures.

Feminine trans individuals (i.e., individuals who were assigned male at birth but who have a feminine gender presentation and identity) are present in many cultures. In some cultures, these individuals identify as (trans) women. Many of these individuals undergo medical treatments to feminize their bodies (e.g., breast augmentation), but most do not undergo vaginoplasties and therefore have penises. In many non-Western cultures, feminine trans individuals identify as a non-binary gender (i.e., neither man, nor woman). Many of these individuals do not surgically augment their bodies. Across cultures, some men express sexual interest in feminine trans individuals. Are manifestations of sexual interest in feminine trans individuals consistent across Western and non-Western cultural settings? Our review suggests that, across cultures, most of these men are also sexually attracted to cisgender individuals. Many are sexually attracted to cisgender women or to cisgender members of both sexes. A small subset is sexually attracted to cisgender men. Men who are sexually interested in feminine trans individuals commonly report being primarily insertive during anal sex. Additionally, they tend to report that their sexual interest in these individuals is motivated by attraction to femininity or to the combination female- and male-typical characteristics.

Facial Attractiveness of the Sisters of Istmo Zapotec Men and Muxes: Implications for the Evolution of Male Androphilia.

Research shows that the female relatives of androphilic (i.e., sexually attracted to adult males) males have more children than the female relatives of gynephilic (i.e., sexually attracted to adult females) males. The mechanisms by which this occurs are unclear. The hypergyny hypothesis suggests that the female relatives of androphilic males have elevated attractiveness which allows them to obtain male partners with higher socioeconomic status, which in turn, provide them with more resources to produce and sustain multiple offspring. We tested whether the female kin of male androphiles are characterized by elevated attractiveness compared to the female kin of male gynephiles. The research was conducted among the Istmo Zapotec from Oaxaca, Mexico, where androphilic males are recognized as a third gender, muxes. We recruited 115 gynephilic men who rated the facial attractiveness of 27 women with at least one muxe sibling and 27 women with only gynephilic male siblings (i.e., control sisters). The results showed that gynephilic men found the faces of control sisters more attractive than the faces of muxe sisters. This finding is inconsistent with the hypergyny hypothesis and suggests that elevated facial attractiveness is not the mechanism by which the female relatives of androphilic males achieve elevated reproduction.

Occupational Preferences and Recalled Childhood Sex-Atypical Behavior among Istmo Zapotec Men, Women, and Muxes.

Research has found that both cisgender and transgender androphilic males (i.e., males sexually attracted to and aroused by other adult males) have female-typical occupational preferences when compared with gynephilic males (i.e., males sexually attracted to and aroused by adult females). Moreover, whereas cisgender androphilic males' occupational preferences tend to be intermediate between those of gynephilic men and androphilic women, transgender androphilic males tend to have occupational preferences that are more similar to androphilic women. No study has directly compared both types of androphilic males within the same culture. The present study investigated occupational preference and its relation to childhood sex-atypical behavior (CSAB), among gynephilic men (n = 208), androphilic women (n = 138), and cisgender (n = 132) and transgender (n = 129) androphilic males from the Istmo region of Oaxaca, Mexico, where androphilic males are recognized as third gender, muxes. The study found large sex differences in occupational preferences (d = 2.80). Furthermore, both cisgender muxe nguiiu (d = 2.36) and transgender muxe gunaa (d = 3.44) reported having more sex-atypical occupational preferences compared with men. However, muxe gunaa reported higher female-typical occupational preferences than women (d = 0.59) and muxe nguiiu (d = 0.57), whereas muxe nguiiu and women did not differ (d = 0.08). These findings are consistent with the conclusion that sex-atypical occupational preferences are a cross-culturally universal aspect of male androphilia. Finally, CSAB was associated with sex-atypical occupational preferences among all participants. These findings suggest that a developmental continuity exists between childhood and adulthood sex-atypicality.

Testing Women's Trust in Other Women and Same-Sex Attracted Males in Three Cultures.

Heterosexual women trust mating-relevant advice received from gay men more than that received from heterosexual women. This trust is predicated on women's perception that gay men lack ulterior sexual motives and romantically pursue other gay men. However, this trust may not hold in all cultures. For example, in both Samoa and the Istmo Zapotec of Southern Mexico, women take part in mate competition against feminine same-sex attracted males-referred to as fa'afafine and muxe, respectively-who regularly engage in sexual activity with masculine men. The present studies sought to replicate and extend research on women's trust in males who are same-sex attracted. Experiments were conducted in Canada, Samoa, and the Istmo Zapotec, with women randomly assigned to consider the likelihood of various mate-poaching behaviors performed by either a rival woman or a same-sex attracted male. In Canada, women were more trusting of cisgender gay men than other women. Similarly, Samoan women were more trusting of fa'afafine than other women. In the Istmo Zapotec, women were equally distrustful of women and feminine muxe gunaa, whereas more masculine muxe nguiiu were rated as more trustworthy than women and muxe gunaa. These results illustrate that women's trust in same-sex attracted males varies both between and within cultural contexts, perhaps impacted by the relative femininity of the male in question.

Women's Reaction to Opposite- and Same-Sex Infidelity in Three Cultures : Data from Canada, Samoa, and the Istmo Zapotec.

Previous research indicates that Euro-American women are more upset by imagining their male partners committing homosexual infidelities than heterosexual ones. The present studies sought to replicate these findings and extend them to two non-Western cultures wherein masculine men frequently engage in sexual interactions with feminine third-gender males. Across six studies in three cultural locales (Canada, Samoa, and the Istmo Zapotec), women were asked to rate their degree of upset when imagining that their partner committed infidelity that was heterosexual in nature, as well as infidelity that was homosexual. In two Canadian undergraduate samples, women reported greater upset at imagining partner infidelity with a female, whereas a community sample of middle-aged women reported equal upset across infidelity types. Samoan women reported substantially less upset at the thought of partner infidelity with a third-gender male (fa'afafine) than with a female. Istmo Zapotec women reported equal upset toward infidelity with a female or a third-gender male (muxe), whereas a second Zapotec sample reported slightly greater upset at the thought of infidelity with a muxe. Results illustrate how cultural contexts moderate the degree to which same-sex infidelity scenarios are upsetting to women.

Samoan Men's Sexual Attraction and Viewing Time Response to Male-to-Feminine Transgender and Cisgender Adults.

In many different cultures, some men express sexual interest in male-to-feminine (MtF) transgender individuals, but others do not. We examined whether, in Samoa, men who are sexually interested in fa'afafine (Samoan MtF transgender individuals) (MSF; N = 40) differed from men who were exclusively sexually interested in women (MSW; N = 41) in terms of their self-reported sexual attraction and viewing times responses to images of MtF transgender individuals who were feminine (e.g., had feminine hairstyles, makeup) but had not undergone gender-affirming surgeries (e.g., breast augmentation), cisgender women, and cisgender men. MSF reported that images of MtF transgender individuals were sexually attractive, although somewhat less attractive than images of cisgender women. In contrast, MSW reported that images of cisgender women were sexually attractive, but images of MtF transgender individuals were not. The groups did not differ in their sexual attraction ratings of men, which were uniformly low. MSF viewed MtF transgender individuals and cisgender women for a similar length of time and viewed both longer than cisgender men. In contrast, MSW viewed cisgender women longer than MtF transgender individuals and they viewed MtF transgender individuals longer than cisgender men. The present study indicates that responses to MtF transgender individuals vary among Samoan men who share a sexual preference for women.

Canadian undergraduate men's visual attention to cisgender women, cisgender men, and feminine trans individuals.

Some heterosexual men express sexual interest in feminine trans individuals with penises. It is possible that this interest arises from a tendency for heterosexual men to be sexually responsive to gender in addition to sex. We compared the self-reported sexual attraction and visual attention patterns of Canadian undergraduate heterosexual men (N = 51) and gay men (N = 20) to nude images of feminine trans individuals with penises, cisgender men, and cisgender women. Heterosexual men were most attracted to cisgender women and fixated on them the longest. However, they were more attracted to feminine trans individuals with penises than to cisgender men. They also biased their attention to feminine trans individuals with penises over cisgender men. This pattern was unique to heterosexual men. Gay men were most attracted to cisgender men and allocated the most visual attention to them. They responded to feminine trans individuals and cisgender women in a relatively similar manner. As such, heterosexual men appear to be responsive to sex and gender, which may account for sexual interest in feminine trans individuals among some heterosexual men.