Best friends forever: It's all in our genes, say scientists

You share the same sense of humour and like the same music but you may be even closer than you realise. Friendship is in our genes, scientists believe, with members of a group of pals sharing the some of same DNA. In other cases, friends have very different versions of the same gene, suggesting opposites do attract.

The intriguing finding comes from the analysis of the results of two large health studies in which samples of DNA were collected and people were asked to name their friends.

Tracking the frequency of six genes linked to personality traits revealed two clear examples of ‘birds of a feather flock together’ and ‘opposites attract’.

The first involved a gene called DRD2 which affects how much pleasure we get from alcohol and cigarettes and other addictive substances. The study revealed that people with a version of the gene that allows them to get buzz from booze tend to befriend others with the same version. Those with a different version of the gene, and so not as reliant on drink to have a good time, also appear to be drawn together.

‘It is not hard to imagine that non-drinkers may actively avoid alcoholics, or that alcoholics may be drawn to environments that non-drinkers avoid,’ said the US researchers writing in the journal Proceedings of the National Academy of Sciences.

The opposite relationship was found for a gene called CYP2A6. Those with a version of the gene linked to having an ‘open’ personality, gravitated to people with a different version of the gene, the Harvard University study found.

The results stood even after the researchers took into account people’s tendency to form friendships with those with live nearby.

Professor Nicholas Christakis said that reasons for us being drawn to those who are genetically similar to ourselves include us being thrown together with people with similar interests in sports clubs or at university. But we may also actively seek out those who are like us – even if we are unaware of the underlying genetics.

For instance, thin people may stick together, unaware that each member of the group lacks genes that make it easy for others to pile on the pounds.

‘Similarly, people might choose to terminate friendships with people whose weight status differs from their own,’ said the professor.

In terms of opposite attracting, we may hunt out people whose personalities complement our own. Or extraverts may meet their quieter pals through work.

‘Certain environments may require specialisation,’ said Professor Christakis. ‘For example, some workplaces may select people with different skills to work together, and if these traits are related to genotypes (genetic make-up), then people may tend to be more frequently exposed to dissimilar people with whom they may have a higher probability of becoming friends.’

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