New study reveals why long-term couples often resemble each other

Couples who have been in a long-term relationship are often told that they look alike. The internet has long been fascinated by how two people in a relationship can look like doppelgangers. Several psychological studies have delved into this phenomenon. One of the earliest studies conducted on this front was by researchers at the University of Michigan, who attributed continued cohabitation to making couples look like each other.

This study, published by Springer, reports that couples who live together for a long time grow to mimic each other's emotions. This, in turn, leads to their facial musculature permanently developing a similar structure due to prolonged social contact.

In a new study conducted in 2020, Pin Pin Tea-makorn and Michal Kosinski analyzed the facial features of over 500 couples. They discovered that couples don't look similar over time, the similarity exists from the beginning. Backed by computer vision technology and plenty of data, Tea-makorn and Kosinski found notable similarities at the start of the relationships, which didn't alter much with time. Their study published in Nature emphasized how a person often chooses a partner who looks like them.

While explaining to CBC why such similarities exist, Tea-makorn said, "There are both biological and sociological reasons people tend to select partners who are similar to them. Not just looks but also personalities, values and socioeconomic status." She added, "People also develop a preference for things that they are familiar with. Since we grew up being familiar with ourselves in the mirror or our family members, we tend to develop likability to people who look similar to us." The researcher pointed out the similarities in facial features in celebrity couples like Benedict Cumberbatch and Sophie Hunter and Gisele Bundchen and Tom Brady.

Norwegian researchers studied this aspect previously in 2013, where the participants were asked to choose the most attractive face among different variants. The variants included a morphing of the participants' faces blended with their partners with other morphed faces. Interestingly, the results of the study published in PLOS ONE were in favor of self-morphed images. If given the opportunity, male and female participants chose a face similar to theirs. Justin Lehmiller, a social psychologist and the author of "Tell Me What You Want," told TIME that people's inclination to familiar-looking faces is natural but happens subconsciously. Though many may claim that "opposites attract," Lehmiller emphasized that we tend to be drawn toward what is familiar to us unknowingly.

Unlike old times, the dynamics of relationships and marriage are constantly changing. People who travel for work or education have a wider option of choosing a partner. While the previous studies attribute the similarities to being in a familiar social setup for a long time, that's not the case anymore. So, as per Lehmiller, the number of couples looking alike might dwindle in the future because nowadays, we cannot be sure what fuels attraction between two people. "Attraction is this very complex phenomenon, and there are so many factors that play a role in it. Initial similarity might lead you to be attracted to somebody, but it doesn't mean you'll have a happy relationship. Attraction is not easy to predict," Lehmiller said.