Nobody wants to be friends with someone who has horrible breath, or bathes once a month. That behavior simply doesn’t create a good first impression. However, some scientists have been looking into whether the molecules wafting off our skin bear unconscious messages to the people around us, affecting who we do and don’t talk to without us even realizing it.

There are many elements that determine what type of people your friends with, like age, area, community and hobbies. Appearance also plays a role. A new study has found that people are more likely to befriend those who smell like them. Researchers at the Weizmann Institute of Science state that a person’s smell can affect much more than previous studies have predicted.

Inbal Ravreby, a graduate student in the lab of Noam Sobel, studied 20 pairs of so-called “instant” or “click-friends.” After the participants completely cleansed themselves, Ravreby collected their natural body odor. The results found showed that the friends had body odors which were extremely similar or matched each other’s.

Ravreby says these click friendships came to be just after participants first met based partly on physiological traits like their smells that unconsciously affect who we choose to be friends with.