RealClearScience reports the results of a study first published online in the
Proceedings of the National Academy of Science (PNAS). The study found that:
Spouses shared more genetic similarities than random pairs from the same population, a phenomenon called genetic assortative mating (GAM). In fact, an increase in genetic similarity of one standard deviation was linked to a 15% increase in the probability of marriage.
Answering the question "why do we find this similarity?" the article continues:
It is well-known that people with similar educational backgrounds tend to marry each other, a phenomenon known as educational assortative mating (EAM). It is also known that educational achievement is partially linked to genetics. Indeed, the authors found that the effect from genetic assortative mating (GAM) explained up to 10% of the effect from EAM, but the direction of causation is unclear.
"Assortative mating" strikes again. N.B. Direction of causation is always a problem for correlational studies like this one.
