Friends are more genetically similar than you might imagine, study shows

Genetics are a funny, tricky thing

Have you ever known someone who you felt that you were meant to know? Maybe you referred to them as your "sister from another mister" or "brother from another mother." Sometimes a friend feels more like family than just a friend. There may be an actual scientific reason for that.

It turns out there is evidence that friends and schoolmates are more genetically similar to each other than strangers.

A study done by the Proceedings of the National Academy of Sciences observed 5,000 American adolescents and found the similarity across the entire genome, our complete set of genes.

Pretty cool, huh?

But how does that even happen? Well, the how is somewhat unclear, but researchers have come up with two well-founded ideas on the matter.

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One explanation is that friends are more genetically similar due to forming their relationship partly on the basis of shared characteristics. Think in terms of being of the same socioeconomic status or same level of education in the family.

Researchers said when characteristics that influence formation of social ties can be passed down through generations, which many are, that tendency for people to have ties with each other can generate genetic similarity between friends.

Another reason, researchers gathered, is that friends are more genetically similar simply because people tend to create friendships within environments that are similar to their own, such as same occupation, community or school. People form bonds on the basis of characteristics they share. That time they share together is basically influenced by their genetics. 

Researchers found friends can have indirect genetic effects, meaning one person’s genes can influence another person’s characteristics.

Basically, you end up spending time with someone because you already likely have similar genetics, and your genetics may become more similar because of the time you spend together.

Evidence was found that indicated a person’s friends and social networks influenced their:

  • education attainment
  • and risk of obesity.

According to the report, a fundamental problem with observing studies of friends is that it can be “challenging to disentangle the effects of friends from effects of characteristics contributing to friendship formation.”

Regardless of the how, there seems to be no doubt that friends really are more genetically similar than strangers.

Do you have a friend who's more like family? You might be more closely related than you think.