What better way to bond with your friends than have similar genes?
Previous research have already shown how people seemed to be genetically similar to their spouses and adult friends. It was also found that humans naturally get attracted to people whom they have something in common. However, it's not yet well explained how and why this subconscious sorting happen.
So, a more recent study by Stanford, Duke and the University of Wisconsin—Madison delved deeper into that to possibly find an answer. They utilized data from Add Health-- a long-term study grades seven to 12 people on the 1994-1995 school year--of 5,000 adolescent pairs (friends) and genetically compared them.
The result? Well, you actually have more in common with your friends than you think. By that I meant friends were more genetically similar than random pairs of people, and about two-thirds as similar as the average married couple. This similarity is prominent enough to detect but is not as strong as of siblings, says author Benjamin Domingue, an assistant professor at the Stanford Graduate School of Education. What's more is that even classmates were about half as genetically similar as friends and significantly more similar than mere strangers!
This can be explained by two possible phenomena: first is social homophily or the idea that humans form bonds based on shared characteristics e.g. genetics. Second is social structuring, or the idea that individuals get drawn to others in their own social environment, which can be partially shaped by genetics.
“Are individuals actively selecting to be around people who are like them, or is it due to impersonal forces, such as social structures, that we all are affected by?” Domingue says. “Our evidence, with respect to friends, suggest that it’s largely the effect of social structures.”
It’s a complicated equation notes fellow study author and University of North Carolina Chapel Hill sociology professor Kathleen Mullan Harris. Genes and social environments intertwine in many ways, she adds.
“Geneticists need to pay attention to the social context when they’re estimating genetic influences on [traits] like education attainment,” she says. “It’s important to pay attention to these shared genetic effects that we speculate are really due to social structure.”
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