The prevalence of fa'afafine relatives among Samoan gynephilic men and fa'afafine.

Androphilia refers to sexual attraction to adult males whereas gynephilia refers to sexual attraction to adult females. In Western populations, androphilia in males is familial, but the precise nature of this phenomenon is unclear. Some studies show that androphilic males have preponderances of androphilic male relatives in the maternal, but not paternal, line. In contrast, other studies show that male androphilia clusters in both the maternal and paternal lines. Low fertility populations are susceptible to producing anomalous patterns with respect to biodemographic correlates of male sexual orientation, which may account for discrepancies in the familial patterning of male androphilia across Western studies. We focused on a high fertility population to determine which pattern, if any, prevailed. The prevalence of androphilic male relatives was compared for Samoan gynephilic and androphilic male probands. Samoan androphilic males are known locally as fa'afafine. Compared to Samoan gynephilic males, fa'afafine had significantly more fa'afafine relatives in their maternal and paternal lines. The prevalence of fa'afafine relatives was not significantly different between the paternal and maternal lines for fa'afafine or gynephilic male probands. These findings indicate that male androphilia is familial in Samoa and that it clusters in both the paternal and maternal lines in high fertility populations. We consider our findings in the context of possible explanations for the familial clustering of male androphilia. In addition, we detail how the data presented here illuminate the prevalence of male androphilia in the Samoan population.

Offspring production among the extended relatives of Samoan men and fa'afafine.

Androphilia refers to sexual attraction to adult males, whereas gynephilia refers to sexual attraction to adult females. Male androphilia is an evolutionary paradox. Its development is at least partially influenced by genetic factors, yet male androphiles exhibit lower reproductive output, thus raising the question of how genetic factors underlying its development persist. The sexual antagonism hypothesis posits that the fitness costs associated with genetic factors underlying male androphilia are offset because these same factors lead to elevated reproduction on the part of the female relatives of androphilic males. Western samples drawn from low fertility populations have yielded inconsistent results when testing this hypothesis. Some studies documented elevated reproduction among the matrilineal female kin of androphilic males, whereas others found such effects in the paternal line. Samoa is a high-fertility population in which individuals reproduce closer to their maximum capacities. This study compared the reproductive output of the paternal and maternal line grandmothers, aunts, and uncles of 86 Samoan androphilic males, known locally as fa'afafine, and 86 Samoan gynephilic males. Reproductive output was elevated in the paternal and maternal line grandmothers, but not aunts or uncles, of fa'afafine. These findings are consistent with the sexual antagonism hypothesis and suggest that male androphilia is associated with elevated reproduction among extended relatives in both the maternal and paternal line. Discussion focuses on how this study, in conjunction with the broader literature, informs various models for the evolution of male androphilia via elevated reproduction on the part of female kin.