What brings friends together? Is it similar backgrounds and life experiences? Is it the same irrational love for a horrible television show? While those attributes are certainly factors, in a new study scientists have discovered that along with shared interests and senses of humor, friends often also share genes.

Speaking of what inspired the study, James Fowler, who is one of the study’s authors and a professor of medical genetics and political science stated to USA Today that, “ Birds of a feather flock together. We all know this is true at a behavioral level, so we wanted to know if it extended all the way to your DNA.”

This theory apparently has some credence as according to the study, friends are often as similar genetically as they would be if they were fourth cousins. The genetic connection is often slight and can be something as simple as similar senses of smell as reported by the The Washington Post.

However, though this study points out that friends often share genetic similarities, there is no specific gene that is shared that guarantees friendship. Furthermore, more research into the subject still needs to be done before the results can be applied to all ethnicities, as much of the test data came from medical research project in which many of the subjects were white according to the Washington Post.

Still, these results about shared genes between friends could provide a lot of information about what influences people to become friends in the first place.

This study was published in was published in the Proceedings of the National Academy of Sciences of the United States.