Researchers from the Korea Advanced Institute of Science and Technology in Seoul have confirmed that women often choose men who resemble their brothers.
Kirsten Dunst and Jesse Plemons, Justin and Hailey Bieber—these couples and many others could easily pass for siblings. So, this isn’t just a coincidence.
Justin and Hailey Bieber
What Did the Scientists Discover?
To find out what people primarily focus on when evaluating potential , the team involved over 41,440 individuals aged 18 to 47. All participants were registered on a popular South Korean dating app, as reported by Daily Mail.
Using , the team analyzed 506,014 interactions among these users. The results showed that when it comes to , women prefer who resemble their brothers.
The reason for this is not entirely clear. However, scientists believe that women typically favor familiar facial features (in this case, those of their brother) because they evoke trust and are associated with safety and reliability—especially if the brother was a significant figure in the woman’s childhood. This way, she potentially reduces the risks associated with finding a partner.
Kirsten Dunst and Jesse Plemons
Meanwhile, tend to prefer women who are different from their own sisters, the researchers noted.
“This finding aligns with the evolutionary logic of avoiding inbreeding. The attraction to dissimilar faces may be an evolutionarily developed mechanism that helps avoid genetic costs and increase genetic diversity in offspring,” the researchers explained in an article published in Computers in Human Behavior.
At the same time, the team acknowledged that partner selection preferences often demonstrate gender asymmetry: men and women typically prioritize different qualities due to various evolutionary and sociocultural factors. These potential differences in priorities may extend to preferences regarding similarities in appearance and personality.
Preferences can depend on context, shifting based on the characteristics of the potential partner, the researchers noted. For instance, a partner’s socioeconomic status (SES) may alter evaluation criteria, shifting the focus between long-term compatibility signals, such as personality, and short-term attractiveness indicators, such as appearance.
Of course, the idea of physical resemblance in partners is not new. There’s even popular content on Instagram dedicated to this concept, inviting social media users to guess whether couples are blood relatives or romantically involved.
