Fathers with more dominant-looking faces are more likely to have sons

A new study published in Adaptive Human Behavior and Physiology suggests that men with more dominant-looking faces may be more likely to have sons as their first-born children. The researchers did not find similar effects for women, nor did they find that self-reported dominance or specific facial measurements like facial width-to-height ratio could predict a child’s sex. These findings add to ongoing debates about how traits related to dominance and mate selection might be linked to biological processes underlying sex determination.

The study was designed to explore whether dominance-related traits in parents—especially physical cues of dominance like facial appearance—are associated with the sex of their first child. The research draws on evolutionary theories such as the Trivers-Willard hypothesis, which predicts that parents in better condition might have more sons, and the maternal dominance hypothesis, which proposes that more dominant women may be biologically predisposed to have male offspring. Despite decades of research, evidence for these theories has remained inconsistent. This study sought to add clarity by focusing on one specific aspect of parental condition: dominance, and how it is perceived in the face.

“I suspect that for many people, observations in everyday life suggest that the characteristics of parents influence whether they have a son or daughter,” said study author Benjamin Zubaly, an incoming PhD student at the University of Michigan. “However, my own intuitions are that the sex of one’s offspring is completely random. I find hypotheses from evolutionary psychology that predict the sex of one’s offspring to be interesting because they allow us to critically test these intuitions.”

The researchers recruited heterosexual couples with at least one child through the platform Prolific, gathering a final sample of 104 parent pairs. To participate, both partners needed to complete surveys measuring their self-perceived dominance and submit facial photographs. These photos were later rated for perceived dominance, attractiveness, and masculinity or femininity by university students. The research team also measured the facial width-to-height ratio, a feature previously proposed as a cue of dominance. For all analyses, the key outcome was whether the couple’s first-born child was male or female.

To assess psychological dominance, the study used three well-established tools. These included a checklist of dominant traits, a dominance subscale from a broader personality inventory, and a scale that measures dominance based on control in social contexts. Participants also submitted facial photos taken under standardized conditions. These images were analyzed both for their physical features and for how dominant they appeared to outside raters. Ratings from students showed high consistency, allowing the researchers to create a reliable index of facial dominance.

The central finding was that fathers whose faces were rated as more dominant were more likely to have a first-born son. This result held even after controlling for facial attractiveness, masculinity, and age. For fathers with neutral facial expressions in their photos, each standard deviation increase in perceived dominance was associated with an 83% greater chance of having a son.

The researchers did not observe similar effects for mothers’ facial dominance. Self-reported dominance did not predict child sex, and facial width-to-height ratio—often proposed as a proxy for dominance—also showed no reliable link to whether a first-born child was male or female.

These findings suggest that facial dominance, specifically in fathers, may relate in some way to biological or behavioral processes that influence offspring sex. One interpretation is that when women have higher testosterone levels around the time of conception—a factor linked to having male children—they may prefer more dominant-looking male partners. This preference, in turn, could influence the likelihood of having a son. Although speculative, this idea aligns with previous work showing that women who believe they will have male children also tend to find dominant-looking men more attractive.

“In our sample of romantic couples, we found that fathers with more dominant-looking faces were more likely to have sons for a first-born child. It is possible that this means when women are higher in testosterone and more likely to have a son they tend to choose more dominant males. However, further research is necessary to understand what processes underlie our findings.”

The study also builds on earlier research by Palmer-Hague and Watson, who found that parental facial dominance—especially when high in both partners—was associated with having a son. However, the current study did not find significant interactions between mothers’ and fathers’ dominance, suggesting that the father’s appearance alone may be more relevant. Notably, while Palmer-Hague and Watson found similar effects for self-reported dominance, the current study did not. The authors suggest this may be due to differences in how people perceive their own dominance versus how others judge it from physical appearance.

“While we find that an aspect of fathers’ dominance was related to offspring sex, other studies have found that mothers’ dominance is also important. Further research can help to confirm whether it is fathers’ dominance, mothers’ dominance, or both that influence offspring sex.”

As with any study, there are limitations to consider. The researchers relied on retrospective data, meaning that parents were asked about their children several years after birth. While statistical controls suggested that the time since birth did not bias the results, future studies should aim to collect data closer to the time of conception. Additionally, although the sample was cross-cultural, self-reported measures of dominance may not translate consistently across different backgrounds, potentially obscuring meaningful effects.

“This project taught me much about performing research in the field of evolutionary psychology, which will be of tremendous benefit as I switch labs to begin my PhD. I look forward to seeing how other researchers help to clarify the relationship between parental characteristics and offspring sex in the future.”

The study, “Fathers’ Facial Dominance Predicts First‑Born Sons in Parent Dyads,” was authored by Benjamin J. Zubaly and Jaime L. Palmer‑Hague.