It is well established that individuals are more similar to their spouses than other individuals on important traits, such as education level.
The genetic similarity, or lack thereof, between spouses is less well understood. We estimate the genome-wide genetic similarity of spouses and compare the magnitude of this value to a comparable measure of educational similarity.
We find that spouses are more genetically similar than two individuals chosen at random but this similarity is at most one-third the magnitude of educational similarity.
Furthermore, social sorting processes in the marriage market are largely independent of genetic dynamics of sexual selection.
Using a nationally representative sample of non-Hispanic white US adults from the Health and Retirement Study and information from 1.7 million single-nucleotide polymorphisms, we compare genetic similarity among married couples to noncoupled pairs in the population…
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So the population they sampled did not include people who normally marry cousins and other close kin (i.e. Middle Easterners, Pakistanis, etc)