All of us have seen that the longer a couple stays together, the greater they resemble each other, and researchers have now revealed why it is so.
University of Michigan psychologist Robert Zajonc conducted an experiment to test how long and happily-clad couples grow facial similarities and gradually start to look like each other physically.
He analysed photographs of couples taken when they were newlyweds and photographs of the same couples taken 25 years later.
The results showed that the couples had grown to look more like each other over time, reports English.news.cn.
In addition, he revealed that the happier that the couple said they were, the more likely they were to have increased in their physical similarity.
Zajonc suggested that older couples looked more alike because people in close contact mimic each other's facial expressions.
In other words, if your partner has a good sense of humour and laughs a lot, he or she will probably develop laugh lines around their mouth - and so will you.
Other evidence has also shown that men and women may be initially attracted to partners with similar personalities.
It turns out we may even be hard-wired to fall in love with people sporting DNA that is similar to our own in some ways.
In a study of twins, University of Western Ontario scientists found that not only did the study participants tend to pick partners with similar genes, the spouses of the identical twins were also more alike than the spouses of non-identical twins.
The study was published in Live Science.