A Retrospective Study of Childhood Sex-Typed Behavior in Istmo Zapotec Men, Women, and Muxes.

Previous research has consistently demonstrated that both transgender and cisgender androphilic males (i.e., males attracted to adult males) display and recall higher levels of childhood female-typical behavior (CFTB) and lower levels of childhood male-typical behavior (CMTB) compared to gynephilic males (i.e., males attracted to adult females). In adulthood, the recalled CFTB and CMTB scores of cisgender androphilic males tend to be intermediate to those of opposite-sex-attracted men and women, whereas transgender androphilic males tend to score similar to women. These studies have been mostly conducted in Euro-American cultures. We examined recalled childhood sex-typed behavior (CSTB) among the Istmo Zapotec-a pre-Colombian culture in the Istmo region of Oaxaca, Mexico, where cisgender and transgender androphilic males are recognized as a third gender, known locally as muxes. The present study sought to determine whether Istmo Zapotec men (n = 180), cisgender muxe nguiiu (n = 63), transgender muxe gunaa (n = 120), and women (n = 138) differ with respect to recalled CFTB and CMTB. Our results indicate that men recalled significantly less CFTB and more CMTB than women. Cisgender muxes scored in between men and women. Transgender muxes scored similar to women. These findings provide further evidence that childhood sex-atypical behavior is a cross-culturally universal and normative developmental aspect of male androphilia, regardless of whether it manifests in the cisgender or transgender form. This is the first study to present quantitative data comparing the recalled CSTB of cisgender and transgender androphilic males from within the same non-Euro-American culture.

Offspring Production Among the Relatives of Istmo Zapotec Men and Muxes.

Male androphilia (i.e., sexual attraction toward adult males) is influenced by biological factors, reliably occurs across diverse cultures, and has persisted over evolutionary time despite the fact that it reduces reproduction. One possible solution to this evolutionary paradox is the sexually antagonistic gene hypothesis (SAGH), which states that genes associated with male androphilia reduce reproduction when present in males but increase reproduction when present in their female relatives. The present study tested the SAGH among the Istmo Zapotec-a non-Euro-American culture in Oaxaca, Mexico, where transgender and cisgender androphilic males are known as muxe gunaa and muxe nguiiu, respectively. To test the SAGH, we compared offspring production by the biological relatives of muxe gunaa (n = 115), muxe nguiiu (n = 112), and gynephilic men (i.e., cisgender males who are sexually attracted to adult females; n = 171). The mothers and paternal aunts of muxe gunaa had higher offspring production than those of muxe nguiiu. Additionally, the relatives of muxe gunaa had more offspring than those of gynephilic men, whereas no such differences were found between the families of gynephilic men and muxe nguiiu. Elevated reproduction by the mothers and, particularly the aunts, of muxe gunaa is consistent with the SAGH. However, the absence of group differences between gynephilic men and muxe nguiiu, and the group differences between the two types of muxes are not predicted by the SAGH. This is the first study to demonstrate reproductive differences between kin of transgender and cisgender androphilic males within the same non-Euro-American culture.

The relationship between fraternal birth order and childhood sex-atypical behavior among the Istmo Zapotec muxes.

Research on male androphilia (i.e., sexual attraction towards adult males) consistently finds that androphilic males tend to have more older biological brothers than males who are gynephilic (i.e., sexually attracted to adult females). This fraternal birth order effect (FBOE) has been well replicated among androphilic males who present publically in a male-typical (cisgender) and a female-typical (transgender) manner. There is some evidence that the FBOE is more pronounced among transgender androphilic males. However, no studies have directly compared both forms of male androphilia within the same culture. This study tested the FBOE, and its association with childhood sex-atypical behavior (CSAB), among the Istmo Zapotec of Oaxaca, Mexico, where both forms of male androphilia are referred to as a third gender, muxes. Our results indicated that both cisgender muxe nguiiu (n = 124) and transgender muxe gunaa (n = 120) were more likely to be later born among brothers than gynephilic men (n = 194). However, the number of older brothers did not differentiate between transgender and cisgender muxes, nor did it predict CSAB among muxes. These findings replicate the FBOE among both cisgender and transgender muxes but show no evidence that it is more pronounced among transgender androphilic males.

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.