You Are Genetically Similar to Your Friend

Friends are as genetically related as fourth cousins!

Choosing friends is not as random as it may appear. There are subconscious factors that induce liking for specific people who are not relatives. Many people are willing to sacrifice limited resources for close friends. Animals would find it bizarre that an organism would share resources with others who are not genetically related. In fact, many scientists believe that the explosion in the size and intricacy of the frontal cortex of humans is mainly because of our complex social ties. Why are we drawn to some people and repelled by others? Is it true that "birds of a feather flock together” and why?

Researchers examined the genome of participants and their friends. They also controlled for shared ancestry. They found that friends were more genetically “related” to each other than to strangers. In fact, the genetic similarity between a pair of friends was similar to fourth cousins! Because the researchers controlled for ancestry, the genetic similarity is unlikely due to shared ancestry.

The researchers examined the topmost similar genes between friends and the results were surprising. Top candidates were genes implicated in olfaction (sense of smell) and in linoleic acid metabolism. These results indicate that friends smell things the same way and/or that certain environments with characteristic odors attract people making them more likely to become friends. Just like infants can accurately identify their mothers’ odors, so can friends.

In the gene wide search for genetic similarity among friends, researchers found a more limited number of genes that were negatively correlated among friends. Specifically, genes that are implicated in the immune system. In other words, we subconsciously select friends who are immunologically different than us.

This too makes sense. It is advantageous that you and your friend would be susceptible to different pathogens or diseases. If you are resistant to pathogen "X" but not "Y" and your friend is resistant to pathogen "Y" but not "X," then when you are both exposed to pathogen "Y," you are likely to get sick but not your friend. Thus, your friend can take care of you (instead of both of you being sick, if you were resistant to the same pathogens). This also prevents the spread of diseases in social circles.

Using data from the Adolescent to Adult Health (Add Health) study, researchers echoed the same findings in a sample of 5,500 adolescents. Friends were more genetically similar to one another than to randomly selected peers (7). Specifically, genetic scores were positively correlated for BMI and educational attainment among friends, but not for height. They also found that schoolmates were more genetically similar to one another compared with random pairs of individuals. These findings suggest that specific environments may attract individuals who are genetically similar (but not related). In fact, when genetic similarity among schoolmates is compared with genetic similarity among friends, similarity between friends was attenuated. Sharing the same environment (school) contributed significantly to the genetic similarity between friends. It is worth mentioning that friends were still more genetically similar than random schoolmates.

It seems that human beings have a sub-conscious that selects friends based on synergy in some genes and complementarity in others. Indeed, friends are the family we choose. A friend can be defined as a "functional kin" who was selected in accordance with this genetic pattern. Now, go hug your friend, or shall we say “cousin”.

Conclusions

· Our bodies and minds are much more complicated than we think.

· Friends are not chosen randomly. They may indeed feel like family and the loss of a friend may hurt as much as losing a family member.

· Social development and trust may be one of the things that distinguished humans from animals

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Do you think anything happens by chance?

#Friendship #Research #MentalHealth #BiologicalFacts