Mini article to dump some studies I may need in future but you may find this information useful too.

Summary:

  • Spouses are more genetically related to one another than they are to random strangers of the same ethnicity (source).
  • Couples who are third or fourth cousins have the greatest number of offspring, likely due to genetic compatibility (source).
  • People choose spouses who have similar facial features to their own, which is a sign of genetic compatibility (source).
  • People choose friends who are more genetically similar to themselves than to random strangers of the same ethnicity; friends are the genetic equivalent of fourth cousins (source).
  • People are “hard-wired” to choose friends/spouses who think like themselves (source).