FHI study: People choose partners who are similar to themselves

– On average, we choose partners who are somewhat similar to ourselves when it comes to BMI and height, but it is the length of education that clearly has the greatest impact. This means that we are now mainly finding partners who have quite the same level of education as ourselves, says researcher Hans Fredrik Sunde at the Center for Fertility and Health at The Institute of Public Health.

Together with other researchers at FHI, he has studied the degree to which different couples resemble each other when it comes to genetic tendencies.

The study was recently published in the journal Nature Communications.

New phenomenon with equal BMI

While the researchers find genetic traces that over a long period of time we have chosen partners with more or less the same height as ourselves, the researchers believe that it is more recently that we now also choose partners who are also similar to us in terms of BMI and length of education.

– Our findings indicate that partner selection based on similarity in height has taken place for many generations, and that the genetic consequences, such as increased differences in genetic predisposition, have stabilised. The same does not apply to BMI or length of education. Here we will probably see increasing differences in genetic predisposition in the coming generations, says Sunde.

However, the researchers saw no evidence that people choose partners who have the same genetic propensity for mental health as themselves.

– Can lead to social inequality

Sunde points out that sorting by choice of partner can contribute to greater social inequality.

– Someone with a low education, and then preferably a low income, gets a partner who also has a low level of education and a low income. Those with a high education and high income also find a partner with the same level of education. There will be increasing differences because fewer people will be in the middle when those with low and high education do not choose each other. Partner choice may therefore be one of the explanations for why we have seen increasing social inequalities in Norway, says Sunde.