Some people say that married couples start to look alike after many years. Is it true?

Scientists checked photos of 517 couples. They compared pictures from the time of the wedding with pictures taken 20 to 69 years later. Both people and a computer program judged the faces. The couples looked a little alike at the start. But they did not become more alike over time.

There is a popular belief that married couples start to look alike after living together for many years. A 1987 study seemed to support this idea, but it included only 12 couples. To check the claim on a larger scale, researchers at Stanford University collected photos of 517 couples, taken soon after their weddings and again 20 to 69 years later.

Facial similarity was measured in two ways: by human judges and by a face-recognition algorithm. Both methods showed that spouses already looked slightly more alike than strangers when they married. However, their faces did not become more similar over the years. This suggests that people tend to choose partners who already resemble them, rather than growing alike over time.

Textbooks have repeated for decades that long-married couples gradually come to look alike. Much of that claim rested on a 1987 study, which compared photos of 12 couples taken at marriage and 25 years later. Its authors proposed that years of empathically mimicking a partner's facial expressions might reshape the face. Twelve couples is a very small number, and a memorable conclusion built on so little data can easily be a product of chance.

Researchers at Stanford University therefore tested the hypothesis again with 517 couples, comparing photos from the start of marriage with images taken 20 to 69 years later. Similarity was judged separately by human raters and by a face-recognition algorithm. The two methods agreed.

Spouses were slightly more alike than random pairs from the beginning, but their resemblance did not increase over time. That matches a wider body of evidence on partners, who tend to be similar in many traits, such as height and education, largely because of whom they chose in the first place and not because they converged. Couples may still seem to grow alike for reasons that have nothing to do with the face itself, such as shared hairstyles, clothing or expectations.