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A new study has added scientific weight to a long-running pop-psychology theory — that women are often drawn to romantic partners who resemble people they grew up with, including their brothers.
Researchers from the Korea Advanced Institute of Science and Technology examined how physical similarity influences attraction by analysing behaviour on a major online dating platform. Rather than relying on self-reported preferences, the team focused on real interactions, studying how people actually rated and responded to potential partners.
To do this, experts analysed data from more than 40,000 users, examining a total of 506,014 interactions between them. Using advanced AI tools, the researchers measured similarities in both facial features and personality traits, allowing them to build a detailed picture of how resemblance plays into attraction.
The findings revealed a striking gender divide. Women showed a “clear preference” for men who looked more similar to themselves, particularly in facial structure. Men, however, showed the opposite tendency — rating women more highly when their facial features were dissimilar to their own.
While the study did not focus specifically on siblings, the researchers argue that resemblance to oneself often overlaps with resemblance to close family members, especially brothers, due to shared genetics and upbringing. This, they say, may help explain why women can be drawn to men who feel visually familiar.
As for why this happens, the researchers pointed to evolutionary psychology and the so-called parental investment theory. In the study, they explained: “[This] suggests women tend to prioritize cues of trustworthiness and familiarity to mitigate the risks associated with partner selection, for which facial resemblance may serve as a heuristic.”
In simple terms, familiarity may signal safety. From an evolutionary standpoint, women have historically faced greater physical and social risks in partner selection, meaning traits associated with trust and predictability may unconsciously carry more weight.
The findings align with previous research suggesting that people often feel more comfortable with faces that resemble those they grew up around. Earlier studies have found that individuals may be drawn to partners who share similarities with parents or siblings, particularly when childhood relationships were positive.
Importantly, the researchers stressed that this does not imply conscious attraction to relatives, nor does it suggest people are deliberately seeking out look-alikes. Instead, the preference appears to operate subtly, shaped by familiarity and learned associations rather than intent.
The study offers a fresh insight into how attraction works in the age of dating apps — suggesting that, even in a digital world of endless choice, deeply ingrained psychological patterns still play a powerful role in who we fancy.
