Ever heard two girlfriends be told they are so much alike they could be sisters?
Heard guys say his friends are just like his family?
Well, according to a research, based on the Framingham Heart Study, they may be right. Their friends could be as close to them genetically, as their fourth cousins.
Researchers determined that people tend to select friends that are genetically similar to themselves.
Researchers compared gene variations between 1,932 individuals, who were not biologically related, and found that friends had more gene variations in common than strangers.
The purpose of the study was "to provide a deep evolutionary account of the origins and significance of friendship," said Nicholas Christakis, a social scientist at Yale University.
The new study is based on research from the Framingham Heart Study, begun in 1948.
The world-wide known study looks at heart disease risks in individuals with European heritage, living in just one community -- Framingham, Massachusetts.
"The increase in similarity relative to strangers is at the level of fourth cousins," said the study in the Proceedings of the National Academy of Sciences.
The study was published Monday, July 14 in the journal Proceedings of the National Academy of Sciences.
When researchers dug deeper into the data, they found that friends were most similar in genes controlling the sense of smell. Our sense of smell, researchers say, may draw us to certain environments, like a coffee house, where we meet people whose noses are tuned like ours. They added that our sense of smell could be one of the mechanisms we use to identify genetically similar friends, reported Discover magazine.
"Looking across the whole genome," said James Fowler, a professor of medical genetics at UC San Diego. "We find that, on average, we are genetically similar to our friends. We have more DNA in common with the people we pick as friends than we do with strangers in the same population."