A recent study published in the Archives of Sexual Behavior has found that slightly feminine men tend to have better prospects for long-term romantic relationships with women while maintaining their desirability as short-term sexual partners. The findings provide initial evidence that genes linked to male same-sex attraction persist because they confer a reproductive advantage to heterosexual men by increasing traits associated with femininity and paternal care.
Same-sex attraction is a heritable trait, yet its persistence at stable rates of approximately 2-10% in the population poses an evolutionary puzzle. In theory, traits that hinder reproduction should face strong negative selection pressures. However, same-sex attraction persists, suggesting it may offer some evolutionary benefit.
“Darwin’s theory of evolution is one of the most elegant and well-supported theories ever posited. Few theories have such a substantial body of consistent evidence. Therefore, when phenomena appear to contradict Darwinian evolution, they are incredibly fascinating to me,” said study author Thomas Felesina of the University of Queensland.
“Exclusive same-sex attraction presents a Darwinian paradox: how does a partially genetic trait that significantly reduces evolutionary fitness remain in the gene pool at relatively high rates? Individuals exclusively attracted to the same sex tend to have far fewer children, so understanding how these genetic factors persist is a compelling question that drives my research.”
The researchers conducted three studies to test their idea, called the “desirable dad hypothesis.” This hypothesis suggests that the same genes associated with same-sex attraction in men can also make heterosexual men more successful in finding partners by making them slightly more feminine. This increased femininity makes these men more appealing as long-term partners because they are seen as having better qualities for being good fathers.
In the first study, the researchers aimed to see if heterosexual men with close non-heterosexual male relatives exhibited traits associated with good paternal care. They recruited 1,632 heterosexual men from the UK and USA using Prolific Academic, an online crowdsourcing platform. The participants completed a detailed questionnaire on Qualtrics, an online survey tool.
The questionnaire assessed several personality traits thought to be related to good parenting: warmth, nurturance, agreeableness, self-perceived femininity, and the number of sex partners. For instance, warmth was measured using items like “I see myself as affectionate” and “It takes some time for me to warm up to others.” Nurturance was gauged with statements such as “I have a soft heart” and “I enjoy interacting and playing with children.”
Participants were also asked whether they had close male relatives (like fathers, brothers, or uncles) who were gay or bisexual. The presence of such relatives was used as a proxy for possessing genetic variants associated with same-sex attraction. The goal was to determine if these men showed higher levels of traits conducive to parental care compared to those without non-heterosexual male relatives.
The results showed that heterosexual men with non-heterosexual male relatives scored higher on measures of warmth, nurturance, and self-perceived femininity compared to those without such relatives. This suggests that genetic factors associated with same-sex attraction may also enhance traits conducive to parenting in heterosexual men.
In the second study, the researchers focused on understanding women’s romantic preferences. They recruited 152 female participants from a mix of university students and Prolific users. Each participant was presented with 18 dating profiles, with each profile portraying a man with either masculine, feminine, or a combination of both masculine and feminine traits.
The traits and hobbies in these profiles were carefully crafted based on previous research into gender-typical behaviors. For instance, a masculine profile might describe a man as adventurous and competitive, enjoying hobbies like camping and golfing. A feminine profile might depict a man as nurturing and sociable, with interests in poetry and baking. A combined profile balanced both sets of traits.
Women rated combined masculine and feminine profiles as the most attractive, followed by feminine profiles, and then masculine profiles. Notably, feminine profiles were deemed more attractive for long-term partnerships, while feminine and masculine profiles were equally attractive for short-term relationships. This indicates that femininity in men might signal superior paternal qualities, making them more appealing for long-term commitments.
“Women rated profiles of men with feminine traits like warmth and nurturance as more appealing for long-term relationships and equally attractive for short-term relationships compared to profiles of men with masculine traits,” Felesina said. “This indicates that slightly feminine men have better long-term partner prospects without losing short-term desirability.”
The final study aimed to explore why women might prefer feminine men by assessing perceptions of paternal ability. The same 18 profiles from Study 2 were used, but this time participants rated how good they thought each man would be as a father. The profiles were presented to 153 female university students. Participants rated the profiles on a scale, indicating their agreement with the statement “This person would be a good father.”
Consistent with the previous findings, women perceived feminine men as better fathers compared to masculine men. Combined profiles were also rated highly, suggesting that a blend of masculine and feminine traits might offer an optimal balance for attracting partners.
Taken together, these findings support the hypothesis that genes associated with same-sex attraction in men might offer evolutionary advantages by enhancing traits conducive to paternal care.
“Same-sex attraction is influenced by many genetic factors, not a single ‘gay gene,’ Felesina told PsyPost. “These genes are pleiotropic, meaning they have multiple effects. My hypothesis posits that these genes were originally selected for traits conducive to childcare, such as warmth and nurturance, which may have been preferred by women in mate selection (because of our extreme altriciality).”
“Heterosexual men carrying these alleles are seen as more desirable partners due to their superior paternal qualities, giving them a mating advantage and leading to fitter offspring. While these traits increase evolutionary fitness up to a certain threshold, beyond this point, the manifestation of same-sex attraction leads to a fitness drop. However, the fitness advantages these genes offer to heterosexual men compensate for the reproductive costs associated with same-sex attraction.”
But the study, like all research, has limitations to consider. Firstly, the researchers couldn’t separate genetic factors from environmental influences in the first study, and some participants may have unknowingly had non-heterosexual relatives who did not disclose their orientation. Secondly, the sample sizes were relatively small and predominantly from the UK, USA, and Australia, limiting generalizability to other cultures.
To address these limitations and further explore their hypothesis, the researchers are planning additional studies.
“We are currently working on a potential follow-up paper where we model the hypothesis as a proof of concept,” Felesina explained. “We use an agent-based model to investigate the ‘desirable dads’ hypothesis as a potential evolutionary mechanism for the emergence and persistence of same-sex attraction in males, specifically whether selection could favor increased feminization in men. Agent-based models simulate interactions among autonomous agents—individuals or groups—to evaluate their impact on the system. By simulating evolutionary processes over generations, our model allows us to examine how specific traits or behaviors might propagate or diminish.”
The study, “The Desirable Dad Hypothesis: Male Same‑Sex Attraction as the Product of Selection for Paternal Care via Antagonistic Pleiotropy,” was authored by Thomas Felesina and Brendan Zietsch.