The geneticist Jim Wilson, at the University of Edinburgh, was shocked by the frequency he found in the U.K. Biobank, an anonymized research database: One in 7,000 people, according to his unpublished analysis, was born to parents who were first-degree relatives—a brother and a sister or a parent and a child. “That’s way, way more than I think many people would ever imagine,” he told me. And this number is just a floor: It reflects only the cases that resulted in pregnancy, that did not end in miscarriage or abortion, and that led to the birth of a child who grew into an adult who volunteered for a research study.
Most of the people affected may never know about their parentage, but these days, many are stumbling into the truth after AncestryDNA and 23andMe tests.
Fun fact, Charles Darwin married his cousin. It used to be a more common among white Britons (and other Europeans, especially royalty lol), but it’s rare now. It is indeed quite common among Britons of Pakistani heritage, buts it’s becoming rarer. And the risk of genetic defects is actually quite small. I don’t think it can be considered incest when its legal.
There is a theory that the reduction in cousin marriage in Europe reduced the power of clan groupings and led to the more indivualistic liberal culture we have now, with both good and less desirable effects (basically, more freedom but weaker communal bonds)