The saying goes that “opposites attract”, suggesting that people are attracted to those who are different to them, complementing each other like yin and yang. But then, another saying states that “like attracts like”, suggesting that people feel attraction to those that are similar to them, helping them bond over similar interests and hobbies. So which is true?
Biologically speaking, it makes sense for people to look for those who are “different” as it allows for a more varied gene pool. This is highlighted by the famous experiment where women were asked to smell and grade the “attractiveness” of t-shirts worn by different men. It was discovered that the t-shirts each woman chose belonged to a men who were most immunologically different to the woman. Every human being has a unique marker on their cells called the major histocompatibility complex (MHC). The more dissimilar the MHC is, the more likely that the person is not related to you genetically. By choosing a mate with a different MHC, your offspring will have an immune system that has a broader cover against various pathogens. It seems that we have an innate ability to smell this difference. The way we do this best, of course, is through the act of kissing.
Psychologically speaking, we appear to find those who look similar to us attractive. Professor Penton-Voak undertook a study where he showed people a book of photos of the opposite gender and asked them to pick the most attractive one. He found that the participants tended to rate the picture with their own face morphed into the opposite gender as most attractive. Other studies have shown that similar personality, interests and hobbies, attitude and life goals were all strong predictors of attraction between two people. This is most likely because of self-affirmation – the theory that suggests that people like receiving confirmation about every aspect of their life and there is no better confirmation than spending time with someone similar to you and discovering said similarities as you connect.
According to studies on this exact debate, researchers determined that similarity is more important in initial attraction, while being different helped the relationship develop over time. Surveys have shown that people tend to be more satisfied in a relationship when their partner was different to them, especially in terms of how dominant – that is, how much they lead the relationship – they are. When two people are similar in dominance, such as both being dominant leading to frequent conflict, while both being submissive will lead to frustration as neither takes initiative.
Another interesting point is that when the couple is complementary, they tend to change each other for the better, such as an active person helping their shy partner improve their social skills while she teaches her partner the importance of keeping his head on when under stress. Through this process, long-term couples tend to become similar over time. Not only that, but because people tend to mimic people close to them, their speech, behaviour, idiosyncrasies and even facial expressions become similar.
However, there is a law of attraction that surpasses both similarity and complementarity. The mere-exposure effect is a psychological phenomenon where the more we are exposed to something, the more we like it. This is further expanded by the propinquity effect that states that the more we see and interact with someone, the more likely we are to befriend or date them. Simply put, just spending more time with or even living in close proximity to someone is a high predictor of them becoming your friend or romantic partner.