If people randomly partnered up, we would expect them to share zero percent of genetic variants for a trait. However, a new study from the Norwegian Institute of Public Health and the PROMENTA Research Centre shows that in Norway, partners shared 37% of genetic variants linked to education. This means that when it comes to education, they are more similar genetically than the expected similarity of half-siblings, i.e., 25%.
Our findings also show that a person can also be assumed to be similar to the partner their sibling chooses, and that one can expect to share 25% of genetic variants for education with an in-law. The study found evidence suggesting that this “selective” choice of partner has been occurring for at least 5 generations, and perhaps much longer than that.
The findings suggest that due to this selective partner choice, resources may end up concentrating within wider family networks, ultimately prolonging social inequality particularly in relation to education and, concomitantly, jobs and financial prospects.