Why do old couples look alike?

A senior couple taking a selfie. — An old couple’s experiences can be reflected in their faces. DjordjeDjurdjevic / Getty Images

Among the raft of books, articles, jokes, romantic comedies, self-help guides and other writings discussing marriage, some familiar ideas often crop up. Few appear more often than the idea that many old couples look alike. You've probably seen it before -- two elderly people walking hand in hand down the street or sitting at a café, resembling each other so strongly that they could be siblings. Do these couples actually look alike, and if so, what's caused them to develop this way?

A study published in the March 2006 issue of "Personality and Individual Differences" may have the answer. Twenty-two people, divided equally between male and female, participated in the study. They were asked to judge the looks, personalities and ages of 160 married couples. The participants viewed photographs of men and women separately and were not told who was married to whom. The subjects consistently judged people who were married as being similar in appearance and personality. The researchers also found that couples who had been together longer appeared more similar.

This in itself may not seem surprising, but the study also offered some answers on why couples may look alike. To start, consider that life experiences can end up being reflected physically. Someone who is happy and smiles more will develop the facial muscles and wrinkles related to smiling. The years of experience of an old couple's marriage, happy or otherwise, would then be reflected in their faces.

Genetic influences are also a factor. A past study showed that genetically similar people have better marriages [Source: Live Science]. Such families have fewer incidents of child abuse and a lower rate of miscarriages. People also appear to be more selfless when involved with genetically similar partners.

In another study, a researcher at the University of Western Ontario determined that when considering friends or romantic partners, a similar genetic profile made up about a third of the selection criteria. We may think subconsciously that people who are genetically similar work better together. Consequently, we look for physical or emotional cues that tell us that this potential friend, husband or wife is genetically similar to us. Of course, couples shouldn't be too genetically similar -- in most cultures, relationships between close relatives are taboo, and geneticists agree that diversity is important to a healthy gene pool.

Besides feeling that they work better together, why and how do people choose partners who are genetically similar? Asking for a DNA sample on the first date would be impolite. The answer may be equal parts personality -- derived in part from genetics and consistently ranked by people as important in a partner -- and the marriage models we have around us. In other words, many women say they want a guy like dad.

Other Criteria for Attraction

Finding out what attracts one person to another has been explored by matchmakers and psychologists alike. But science has been able to go beyond many of the classic answers, such as sense of humor, kindness, intelligence and similar values. The genetic basis of attraction may be equally important while also representing a bigger mystery.

A study involving researchers from several universities showed that women prefer men who look like their fathers. Even women who were adopted seem to share the same predilection. Tamas Bereczkei, a researcher at Hungary's University of Pecs who was involved in the study, called the process sexual imprinting. Women use their fathers as models by which they judge their prospective mates.

The study also found that a close father-daughter relationship more often resulted in a woman marrying someone who looked like her father. Again, the notion of imprinting arises as these fathers, by forming close emotional bonds with their daughters, seemed to provide a model of what a husband should be.

Other studies have shown that the waist-to-hip ratio provides a subtle but important cue in determining attractiveness. Men prefer women with a waist-to-hip ratio of 0.7, which means that a woman's body appears capable of producing healthy children. Women often prefer men with a waist-to-hip ratio of 0.8 to 1.0, though other features like height or a broad chest are also important. Not by coincidence, waist-to-hip ratio has a genetic basis. Our hormones determine where the body accumulates fat, and a desirable waist-to-hip ratio would indicate a proper hormonal balance, and consequently, a healthy mate.

Symmetrical facial features are considered to be another desirable trait. Implicitly, symmetry is a sign of good development and the ability to produce healthy children. In past studies, test subjects rated more symmetrical men and women as healthier and more attractive. Dr. Randy Thornhill, an evolutionary biologist at the University of New Mexico, found that men who are more symmetrical have more sexual partners than their less-symmetrical peers. One reason, Thornhill says, is that women are frequently the objects of competition, so they're able to be more selective [Source: Live Science].

In the end, it appears that genetics and shared experiences are very important, not only in the partners we choose but also in how we grow old together. We generally want someone who's like us and like the role models we know, but we also want, as the saying goes, someone with whom we can grow old and who will change and adapt with us in the years to come. It just so happens that, when that experience works out, we can end up looking like the person we love.

For more information about the genetic basis of attraction and related topics, please check out the links on the next page.

Dog Look-alikes

It's not just elderly couples -- some people look disturbingly similar to their canine friends. A 2004 study showed that people shopping for purebred dogs often pick one that in some way looks like them. When a person chooses a purebred, he or she puts a lot of thought into how the dog will look when it's older; a mutt-purchaser is more likely to make a quick decision. But unlike old married (human) couples, researchers found that shared experiences don't cause dogs and their human masters to develop similar features -- rather, they look alike from the start.

Why do old couples look alike?

Other Criteria for Attraction

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