Individuals who possess a strong desire for novelty and intellectual exploration tend to have fewer children over their lifetimes. A recent study published in Evolutionary Behavioral Sciences provides evidence that this happens because these individuals often delay parenthood, experience shorter romantic relationships, and report fewer positive motivations for starting a family. These findings help clarify how specific personality differences influence reproductive choices in modern society.
Aleksandra Milić, a graduate student at the University of Pavia, and Janko Međedović, a professor at the Institute of Criminological and Sociological Research in Belgrade, conducted this research. The scientists wanted to understand human behavior through an evolutionary perspective. Specifically, they focused on a psychological trait known as Openness to Experience.
This trait describes people who are highly imaginative, intellectually curious, and open to new ideas. Previous studies consistently indicate a negative association between this trait and fertility. In biological terms, this means that highly open individuals tend to leave behind fewer descendants.
Milić and Međedović wanted to identify the specific lifestyle and relationship factors that explain this reproductive trend. “We were motivated by the limited research on Openness to Experience within a human behavioral ecology framework, which views personality traits as potential adaptive responses to environmental conditions,” Milić explained.
She noted that human personality has biological roots and evolutionary consequences. “While personality traits are known to have genetic components and may therefore be subject to natural selection, little research has examined how Openness relates to reproductive motivations and outcomes,” Milić said.
The scientists noticed a significant gap in the scientific literature regarding why this specific personality type leads to smaller family sizes. “To our knowledge, for example, no prior studies have examined the association between Openness and reproductive motivations,” Milić added. “We wanted to better understand whether and how individual differences in Openness might shape reproductive behavior in modern environments.”
To explore this dynamic, the researchers surveyed 1,024 individuals online. The sample was relatively young, with an average age of 32.3 years. It included a fairly even split between men and women.
The scientists used a snowball sampling technique to gather their data. This is a recruitment method where initial participants share the survey with their own social networks. Participants completed a standardized personality questionnaire that measured their level of Openness to Experience.
The survey also asked for their total number of children, their age when they had their first child, and the number of sexual partners they had experienced. If participants did not yet have children, they indicated the age at which they hoped to start a family. The researchers also asked participants about the length of their longest romantic relationship.
Finally, the survey included a comprehensive scale assessing both positive and negative motivations for having children. Positive motivations included factors like personal fulfillment and continuing a family line. Negative motivations covered concerns like financial stress, childrearing burdens, or physical changes to the body.
The data analysis revealed that individuals with higher Openness to Experience indeed reported having fewer children. The researchers identified three main factors that explained this connection. Highly open people tended to wait longer to have their first child, reported shorter long-term romantic relationships, and expressed fewer positive reasons for wanting to become parents.
“The main takeaway from our findings is that, in our sample, people higher in Openness to Experience tended to have fewer children,” Milić told PsyPost. “Higher Openness was associated with later entry into parenthood, shorter romantic relationships, and less positive motivation to have children, all of which were linked to fewer children.”
Milić noted that these interconnected variables paint a clear picture of reproductive decision making. “Taken together, these factors help explain how personality differences may shape reproductive outcomes over time,” she explained.
The scientists found no significant link between Openness and the total number of sexual partners. They also found no relationship between the trait and negative feelings about having children. Highly open people simply felt less drawn to the positive aspects of parenthood.
“One interesting finding was that individuals higher in Openness tended to have shorter romantic relationships, but not a greater number of sexual partners,” Milić said. “This suggests that the association with lower fertility may not be related to increased mating behaviors, but rather to lifestyle flexibility and changing priorities over time.”
She pointed out that highly open individuals are not necessarily against the idea of families. “We also found that individuals high in Openness did not report stronger negative motives for having children, suggesting that the results may reflect reduced social pressure and alternative life goals rather than negative attitudes toward parenthood,” Milić added.
The scientists noted a few limitations in their research design. The study relied on a cross-sectional format, meaning the data was collected at a single point in time. This prevents the researchers from proving strict cause and effect relationships.
“The study was cross-sectional, which means we cannot draw conclusions about causality,” Milić cautioned. The age of the participants also presented a challenge, as many had not yet finished building their families.
“Many participants were still within their reproductive years; therefore, their final number of children is not yet known, and patterns may differ in samples of individuals who have completed reproduction,” Milić explained. This means future studies will need to look at older demographics to confirm these patterns.
The sample demographic was also slightly skewed toward higher socioeconomic groups. “Additionally, the sample included a higher proportion of highly educated individuals, which limits generalization to the broader population,” Milić said. “Finally, Openness was measured using a short scale that may not fully capture the complexity of the trait.”
Looking ahead, the researchers hope to track how personality influences family planning across entire lifespans. They are also curious about how intelligence, which frequently correlates with Openness, factors into these reproductive trends.
“Future research should examine further factors that may mediate the relationship between personality and fertility, particularly values and attitudes,” Milić said. “In addition, a better understanding of how Openness interacts with intelligence may help clarify broader patterns in reproductive decision-making.”
She hopes to see studies that follow people as they age to see how their choices unfold. “Longitudinal studies following individuals across the reproductive lifespan would be especially valuable,” Milić concluded.
“To further motivate this line of research, we would like to share a recent book by Dr. Međedović for readers interested in the topic, which explores traits such as psychopathy within a behavioral ecological framework. The book is available at the following link: https://doi.org/10.1007/978-3-031-32886-2.”
The study, “Rethinking Parenthood: Mechanisms Mediating the Negative Link Between Openness and Fertility,” was authored by Aleksandra Milić and Janko Međedović.