Why Do Some Couples Look Like Brother and Sister?

Couples that look alike might sound quirky, but there are a few scientific reasons behind their resemblance. Here are a few more reasons why there are couples that make us wonder whether they are dating or siblings:

1. The mere exposure effect: Sometimes, in love, we choose partners with similar genes, giving us a physically similar appearance. Our tendency to choose people with similar traits is pretty instinctive. The “mere exposure effect” is a behavioral deed in which we prefer faces, bodies, places, and things we are already comfortable with (like choosing the same race, for example). 

2. Copycat partners: Ever notice how couples start mirroring each other’s expressions? It happens, and suddenly, they’re unintentionally acting like siblings who grew up together. When couples vibe, they naturally pick up each other’s habits and body language, signaling a solid emotional bond and trust. Scientists state that partners tend to influence each other’s habits throughout a long-term relationship, like marriage (having together a healthier lifestyle, for example). 

3. Love glow: There’s this thing called the “love glow.” It makes couples radiate happiness when they’re seen together. Their mutual glow makes us perceive them as a couple that looks alike. Psychologist Robert Zajonc’s study in 1987 suggested that couples can begin to look alike over the years based on factors such as diet, lifestyle, and compatibility. However, researchers Pin Pin Tea-makorn and Michael Kosinski at Stanford University did clinical tests to prove it. Still, the mere exposure effect took place again. There’s no clinical evidence that couples go through a face-shifting wonder after years of relationship.

4. Perception: Contrary to the belief that external factors like hairstyle lead to a couple’s similarity, experiments show that even after removing extrinsic features, faces in couples are perceived as more similar. It’s so popular to notice couples that look like siblings that the New York Post even named them “doppelbangers.”

5. Personality and age: Couples that look alike are also perceived as similar in personality and age. These factors independently contribute to facial similarity in couples.

To sum up, looking alike doesn't guarantee love compatibility, but it’s a fun twist in the love story. Compatibility comes from shared values, communication, and understanding. That’s where the genuine connection really matters.