﻿Have you ever walked past two people and noticed they look kind of similar and you aren’t sure
whether they are in a romantic relationship or are actually related to each other? Or
maybe you’ve come across the popular Siblings or Dating challenge online, which is now an
entertaining Instagram account with 1.2 million followers. A lot of us probably think that some
of these couples look freakishly too similar and might wonder if this is a real phenomena
that’s present in many different cultures. There is even a widespread term in Chinese called “Fu Qi
Xiang” that applies to couples that look alike. In Chinese culture physical resemblance amongst
partners is deemed very lucky and signifies that the couple were born to be together and thus their
relationship is less likely to break down. Studies have found the case of facial similarity
between couples to be true in Venezuelan, East and West Asian, and European raced partners. Research,
particularly by Hinsz, and Alvarez and colleague will help us make sense of why it happens. some
research can help us understand it. People tend to choose their romantic partners
based on similar interests, values, intelligence, social class and physical attractiveness. A study
by Alvarez and Jaffe suggests that some of these couple pairings could be due to narcissism.
Whereby if you find yourself attractive, then it makes sense that you would choose someone
that matches your level of attractiveness and thus a partner that looks like you. However,
Hinsz gives us another possible explanation, that if a partner’s face resembles your own and thus
your family members …. You will subconsciously trust this person more from the outset
because their face is similar to the ones that you’ve been exposed to most frequently
and that you trust the most. When looking at long term couples,
what could be some of the mechanisms that drive their similarities? Maybe they are similar from
the outset of their relationship or over time they become more similar to each other due to shared
life experiences and repeated interactions. For the latter argument, Zajonc and colleagues
corroborates it with their seminal paper in 1987: ‘Convergence in the Physical
Appearance of Spouses’. It was the first study to attempt to find evidence of facial convergence,
meaning over long periods of time peoples’ facial features can grow physically similar.
Selecting romantic partners that are similar to you either physically or socially, at a level
above chance is known as positive assortative mating. On a tangent, these behavioural mechanisms
can even come into play when people choose their pets. One possible hypothesis for this phenomenon
by Hinsz from the North Dakota State University was the repeated exposure explanation. Which is
that mere repeated exposure to a stimulus, such as human faces will lead to a more positive attitude
to it. For the majority of people, the faces that they have seen most frequently in their life will
be their own, through mirror exposure or through photos, and their family’s faces such as their
parents, siblings and extended family members. Therefore you would develop a greater attraction
for potential partners that are genetically unrelated yet similar facially to you.
Another explanation for why some couples look like siblings is the matching hypothesis,
which suggests that when making dating and mating choices, individuals choose those who
match themselves in terms of desirable social and physical qualities. Therefore we don’t just
go for the most attractive person in the room. This form of compromise is essential in order
to avoid rejection. Pursuing someone that is out of your league has a less chance of success
than someone in the same league as you. People probably do not consciously set out
to find a partner that resembles themself but they develop a subconscious narcissism
through repeated exposure to their own face and those of their family and other genetically
similar faces. Leonardo Da Vinci wrote some wise advice in his notebook for artists for when they
choose beautiful faces to paint. That the artist must search for models with faces deemed beautiful
by the public rather than his own personal preference, as their own wit might deceive them,
and it will lead to him choosing a model with a face similar to his. And this might not go
down well if the artist has an ugly face. Returning back to Zajonc and colleagues’ 1987
study, they found that faces of married couples were not similar from the beginning of their
relationship, but actually became more similar over time. In order to come to these results, they
compared photographs of spouses when they were newly married and 25 year later. Their hypothesis
was that long term couples co-existed in the same environments for significant periods of time.
During their marriage, couples eat the same foods, mimic each other’s emotional expressions and are
exposed to the same climate. Repeated emotional mimicry might account for this because humans are
empathetic creatures and it is not uncommon when your loved one is in pain or in a state of joy,
you feel their pain and joy yourself and therefore you unconsciously and involuntarily
produce similar facial expressions as they do. For instance, if two partners smile a lot and
make each other smile, then over time they might co-develop similar smile lines and other wrinkle
patterns. In terms of diet, most couples tend to share common diets and over time eating the
same foods with similar fat content can lead to similar levels of fatty tissue in the face.
However upon closer look, Zajonc et al.’s study lacks empirical support.
Firstly, the study had sample size of 12 European, married heterosexual couples, which nowadays would
be deemed as an unacceptably small sample size. Also, the findings have never been replicated.
Therefore researchers Tea-makorn and Kosinski from Stanford University performed a larger-scale
follow up study with 517 white married heterosexual couples. They got 2 sets of
photos of each couple, one 2 years after the wedding and the other 20 to 69 years later.
To measure facial similarities, they used human judges and a facial recognition algorithm
software. From these 517 couples, the researchers produced over 2000 unique stimulus sets. Raters
were shown the target face (the face at the top of their screen) and 6 other opposite sexed faces
which included the target’s spouse. The raters had to rank the 6 faces from 1 to 6 from most (1) to
least (6) similar to the target face. Each stimulus set received 10 separate rankings
and these results were averaged. Therefore, if there was no correlation between being
married and facial resemblance, then the couple’s average rank should be 3.5. The facial recognition
software used has a history of outperforming humans in recognising facial similarity.
They work by converting images of faces into vectors that capture different facial features
and then they compare the vector sets of different faces. They are also aimed to judge images taken
at different angles, with different facial expressions, background and lighting.
The study found that spouses do have a tendency to have similar faces as rated by the human judges
and the facial recognition software. The average rankings for the spouses’ faces by human judges
were 2.75 and 2.89 from the facial recognition algorithm. Perhaps the notion that opposites
attract isn't true after all. However they found that spouses’ faces did not converge over time.
In fact, human judges found that married couples’ faces became slightly less similar if they were
married for longer. But this was not replicated by the facial recognition algorithm.
Busting the previous finding that couples’ faces don’t become more similar over time might not not
be exciting. But it can be viewed as good news for couples that are ending a long term relationship,
you might be going through a messy divorce and have grown a mutual hatred but at least
you both haven't grown to look like each other even more than you might already do.