GWAS shows BFFs share DNA

People may actively seek friendship with genetically
similar individuals, a controversial study has suggested.

The study looked at genetic information and friendships of
more than 2,000 individuals using data from a multi-decade heart study from
Framingham, Massachusetts. Using a genome wide association study (GWAS),
researchers compared thousands of genetic markers in the genome called single nucleotide polymorphisms (SNPs). These markers were compared with those from study
participants identified as friends or strangers.

Friends were seen to share a greater genetic similarity than strangers
at around one percent, a level similar to that of fourth cousins. Similarities among friends were
especially strong in genes related to smell.

'One per cent
may not sound like much to the layperson, but to geneticists it is a
significant number', explained co-author Dr Nicholas Christakis from Yale University. Although low, this level of variance is
comparable to the best genetic methods for predicting schizophrenia, bipolar disorder, and body mass
index.

The results of this study support the idea that human
genetics may not only be influenced through reproduction, but also though
friendship.

The co-authors of the study are no strangers to
controversial views on genetics including linking a particular genetic variant
to political views during the US
election season (see BioNews 583), and even genetics' role in popularity (see
BioNews 493) over the past few years. Critics have once again raised
significant concerns about the conclusions drawn from the most recent study.

'These studies depend upon that assumption - that you're
looking at thousands of people who are not related,' Professor Evan Charney from Duke
University told
the BBC, but the relationships between study participants can be difficult to confirm. The overwhelming
majority of participants in the Framingham
dataset come from a similar ethnic background and are from the
same town.

Dr Rory Bowden from the Wellcome Trust
Centre for Human Genetics in Oxford also expressed concerns
about the study's ability to account for factors that might lead to a
spurious associations 'because they reflect differences in places of origin
within Europe of the Framingham participants'.

But Professor Robert Seyfarth from the University of
Pennsylvania, who was not involved in the research, told the Washington Post he was encouraged by the results: 'this is a very interesting, provocative
answer to the question of why is it that humans are so hyper-social in their
interactions. Why are they so friendly to strangers? Most animals don't encounter
strangers at all'.

Currently, no comparable dataset is available to confirm
the results of the study elsewhere.

The authors
have acknowledged the current study's limitations. Co-author Dr James Fowler from the University of California
explained: 'While we've found that this is true for this one well-studied group of people, we
don't know if the
results can be generalised to other ethnic groups, my expectation is that it will, but we don't know'.