A new study suggests that fathers who hold traditional beliefs about masculinity experience sharper drops in testosterone when caring for preschool-aged children, challenging the idea that traditional manhood is allied with higher hormone levels. The research, published in Hormones and Behavior, indicates that while baseline testosterone is not tied to men’s beliefs about gender roles, the degree of testosterone change during solo caregiving relates to traditional masculinity ideology.
The study frames testosterone as a fluid response to social situations, not a fixed measure of masculinity. Lead author Patty X. Kuo, an associate professor at the University of Nebraska-Lincoln and director of the Nebraska Strong Families Lab, emphasised that masculinity is often inferred from proxies such as facial features or aggression, rather than a shared conceptual definition. “This sample of fathers is also interesting to study when it comes to masculinity and testosterone because there is this well-known theory called the ‘Challenge Hypothesis’, which proposes that testosterone decreases in males can facilitate parenting behaviour,” Kuo explained. “So men actually decrease in testosterone when they become fathers, but US society has also made ‘low T’ a problem, at least according to some. I wanted to put all of these pieces together to see what we could learn about testosterone and masculinity ideology among fathers.”
The team recruited 42 fathers with 3- to 5-year-old children from the Midwestern United States between February 2020 and July 2023. Participants ranged from 24 to 52 years old, with an average age of about 37; most were white, and nearly all were married and employed full-time. Before laboratory visits, fathers completed an online survey measuring their endorsement of traditional masculinity ideology—agreements with five statements about how men should behave on a 1-to-7 scale.
Each father then spent an hour in a lab session alone with his preschooler, collecting saliva samples at three points to track short-term testosterone reactivity. The first sample established a baseline roughly 15 minutes after arrival. The episode began with a 25-minute separation-and-reunion task designed for preschoolers, featuring periods of free play interrupted by two brief separations when the father left the room before returning via a two-way mirror.
After the separation task, the fathers provided a second saliva sample, followed by a 20-minute session of routine parenting tasks—cleaning up toys under time pressure and then guiding their child through three challenging puzzles without direct physical help. A final saliva sample was collected after these tasks.
Across the full group, average testosterone did not change significantly from the start to the end of the visit. On average, testosterone fell by 2.46 per cent after the separation task, though this shift was not statistically significant and individual responses varied widely. This contrasts with a 2016 study led by Kuo that observed declines during separation for fathers of infants, with no further drop during teaching tasks; the authors suggest preschoolers’ calmer reactions may partly explain the difference.
While baseline testosterone showed no link to masculinity beliefs, the study found that the way hormones moved during the visit did. Controlling for time of day, lab batch, and whether the father was the primary caregiver, stronger traditional masculinity beliefs predicted steeper testosterone drops—a modest but notable relationship. The authors report that masculinity beliefs explained roughly 15 per cent to 18 per cent of the variation in hormone changes.
The average masculinity score in the sample was 2.98 on a 1-to-7 scale, below the midpoint of 4, indicating a general leaning away from traditional norms within the group. For each one-point increase in the masculinity ideology score, a father’s testosterone fell an additional 5.99 per cent from baseline to the end of the separation task, and by 7.28 per cent from baseline to the end of the puzzle task. Importantly, the link appeared most pronounced between the baseline and the end of the separation task, rather than between the second and third measurements.
As Kuo cautions, “Being a ‘high T’ man does not mean that you are more (or less) masculine. Men’s testosterone fluctuates according to the situations that we are in – including interacting with their children. The men who self-reported having more traditional masculine ideals actually decreased in testosterone while interacting with their children more than the men who had less traditional masculine ideals.”
In an interesting subgroup, nine fathers identified as their child’s primary caregiver showed an average testosterone increase of 8.46 per cent after the separation task, compared with an average decrease of 9.52 per cent among 14 fathers who shared caregiving equally. Across the full visit, primary caregivers showed an average 5.52 per cent rise versus an 11.71 per cent fall among those with more egal caregiving roles; however, this difference was not statistically significant once other factors were considered, largely due to the small sample.
The authors offer a possible explanation for why traditional views might relate to larger testosterone drops: solo caregiving in an unfamiliar environment could prompt a shift away from a protector role toward nurturing, triggering a stronger hormonal adjustment. By contrast, primary caregivers may approach tasks as routine, potentially sustaining or increasing testosterone, while those sharing caregiving might feel a greater need to provide comforting care—though the study did not measure perceived novelty or role during the visit.
Limitations acknowledged by the researchers include the modest sample size and its lack of diversity: the 42 participants were largely white, married, and well educated, based in the Midwest. The study’s correlational design cannot establish causation, and it did not track fathers’ real-world behaviours outside the laboratory or measure other hormones such as cortisol that might interact with testosterone during parenting challenges.
The researchers emphasise that replication in larger, more diverse samples is needed, alongside investigations into actual parenting behaviours and stress hormones. Still, the findings challenge stereotypes that equate traditional masculinity with elevated testosterone and instead suggest that a father’s beliefs about manhood may shape how his body responds to caring for a young child.
The study, “Traditional masculinity ideology enhances testosterone reactivity in human fathers of preschoolers,” was authored by Patty X. Kuo, Maxwell Lottes, Jiabin Lyu, and Ali E. Shull.
