Do Couples Start To Look Similar The Longer They’re Together?

1987 Research vs 2020 Research

A study conducted in 1987 by Robert Zajonc at the University of Michigan suggests that couples’ facial composition changes the longer that they’re together. Zajonc’s study photographed a small sample of couples over several years and then called on volunteers to match men and women who looked most similar. The results indicated that after several years of marriage, many of the couples resembled one another, while the younger versions of these same couples only showed slight resemblance. Dr. Zajonc hypothesized that the increased facial similarities between couples can be attributed to shared lifestyle, like diet, hobbies, mood, environment, etc. He explained that couples often mirror one another’s facial expressions which can create the same face shape, muscle definition, wrinkles, and skin texture over time. 

There’s no question we unwittingly use our facial muscles in the same way as the person we’re looking at.

Zajonc went a step further in his research and claimed that the happier the couple, the greater the resemblance will become over time. He cited science on how when one partner imitates the other’s facial expression, the two are, by default, sharing emotions, which creates greater empathy and, therefore, a deeper bond.

Modern psychologists have had plenty of time to critique Zajonc’s work – over 30 years, in fact – and many have questioned the validity of his evidence. Some of Zajonc’s peers argue that sharing facial expressions does not necessarily mean sharing emotions at a neurochemistry level. Others completely reject his findings because his study’s sample population was small and homogenous, and its findings have never been replicated.

In 2020, psychology Ph.D. students at Stanford University conducted a modernized version of Zajonc’s study and found completely contradictory evidence. Instead of using 12 couples’ photos, they used photos from over 500 couples over a broader time span. And instead of calling on volunteers to match the look-a-likes, the students used facial recognition technology to analyze the level of facial similarity. The study found no evidence supporting the theory that couples look alike the longer that they’re together. However, this 2020 study not only complicated our understanding of whether couples look more alike over time, but it led psychologists to an entirely new topic of research. 

The New Question

Like all good scientific studies, the 2020 Stanford study pointed researchers to more questions. While couples may not begin to look like one another over time, this study instead suggests that couples tend to look alike from the start. The new question we should be asking ourselves is: Why are we more likely to prefer a partner with similar facial features to our own? This question is not an entirely new one and has been studied by psychologists for several decades. There are even gestures to this phenomenon in pop culture, as seen on the show Siblings or Dating? Let’s explore some of the most supported hypotheses to this research question.

1. The Familiarity Effect: One possible explanation for why people choose partners who look like them is because of the familiarity effect. Our brains tend to prefer “familiar stimuli,” according to researchers from Psychology Today, because when we’re exposed to the same stimuli over and over again, it becomes easy to understand. In a study testing the impact of the familiarity effect on beauty perception, more distinct faces were rated less beautiful than more simple or familiar faces. The conclusion here was that the human brain prefers what it already knows – and this applies to other contexts aside from choosing a life partner. 

2. Ingroup Bias: This phenomenon explains the tendency to prefer those who belong to the same race, ethnicity, class, or social network as you. Ingroup bias has been proven present in many racial backgrounds – whites, blacks, Latinos, and Asians, among others. Even biracial individuals, despite their racial diversity, tend to prefer those who share their same race. Scientists continue to study why ingroup bias exists, but it comes down to a combination of biological and social influences. 

3. Sexual Imprinting: When we are young, we learn everything from our parents, especially when it comes to relationships because our parents are the first couple we’re exposed to. This theory suggests that humans subconsciously select partners who look like their opposite-sex parent, and ultimately resemble themselves. Humans are not the only species to do this – the same tendency has been found in both aquatic and land animals as well.

There are several theories beyond these that psychologists have used to explain why people choose partners who look like them, but these are just a few of the heavily researched explanations. 

Closing Thoughts

The 1987 and 2020 studies on whether couples begin to look alike over time point to an important theme in scientific research – that research outcomes morph over time. Just because a study once proved something to be true doesn’t mean that its evidence still holds, especially if research methods have become outdated. At the time, Zajonc used the best methods available to him to answer the question of whether couples look alike after significant time. And in 1987, his findings were accepted as truth because nothing had proven them wrong yet. 

However, as years passed and no other study could replicate its findings, skepticism grew among psychologists. Finally, in 2020, the use of modern methods like facial recognition and a larger sample size proved Zajonc’s findings incorrect. Scientists are constantly critiquing each other’s work in a process called peer review because new facts and evidence come up that point to different outcomes. This is not to say that you should never take study findings as truth, but be cognizant of the amount of support there is behind the research you believe. 

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