Parents undoubtedly play a role in their children’s understanding of gender and sexual health. But can children have any effect on their parents? In a study investigating how becoming a father influences men’s sexual behavior, sociologist Abigail Weitzman finds that the gender of a father’s firstborn child has a significant influence on that father’s likelihood of being sexually promiscuous later in life.

Using 61,801 Demographic and Health Surveys from 37 developing countries, Weitzman looks at how the sex of a firstborn child influences the father’s sexual health and behavior. The survey provides information about whether or not fathers pay for sex, use condoms, have extramarital sexual partners, and report having genital ulcers or genital discharge, which may be signs of an STI. Through fixed effects models that control for differences between countries, Weitzman finds that fathers with firstborn sons are significantly more likely than those with firstborn daughters to pay for sex, and they are also less likely to use condoms. Fathers of firstborn sons also have a higher probability of reporting genital ulcers or genital discharge. Additionally, fathers with firstborn sons reported having slightly higher opposition to women’s sexual autonomy. In short, fathers with firstborn children who are male are associated with higher rates of promiscuity.

Interestingly, these differences among fathers tend to emerge when their firstborn child reaches adolescence, suggesting that family gender dynamics shift as children reach puberty and young adulthood. Though the data cannot fully explain why firstborn adolescent sons are associated with more promiscuous behavior among fathers, Weitzman speculates that perhaps fathers of firstborn adolescent males are more likely to engage in sexual promiscuity as a means to maintain, reinforce, and teach masculine behavior and identity. Weitzman’s study may have just scratched the surface of an important set of new questions about how fatherhood, gender identity, and sexual behavior around the world intertwine with family.