University of California researchers think they have the answers. The reason you become friends with some people and not others could be explained by the fact that you share certain genes with them. So no wonder some of your friends feel more like family.
Writing in the Proceedings of the National Academy of Sciences, the experts examined data from two large studies and discovered a link between certain genes and a stronger likelihood of people carrying those genes being friends.
One of those genes - called DRD2 - is linked with an increased risk for alcoholism. In the study, people with that particular gene were 10% more likely to be friends than would normally be expected. And if you're thinking it makes sense, since people with the gene for alcoholism may naturally meet in pubs or bars, the study claims the effect is also seen in children and teenagers.
Another gene called CYP2A6, which scientists believe is involved with openness to new experiences, has the opposite effect. If you carry this gene, the researchers claim, you're more likely to make friends with other people who don't have it.
It's all very fascinating, and could start to explain the chemistry you feel with some people but not others. It also suggests how important our genes are in shaping our social environment.
Who do you feel closer to? Family members or friends?