Midwives have been told about the benefits of “close relative marriage” in training documents that minimise the risks to couples’ children.
The documents claim “85 to 90 per cent of cousin couples do not have affected children” and warn staff that “close relative marriage is often stigmatised in England”, adding claims that “the associated genetic risks have been exaggerated”.
It also compounds over generations; if you’re the child of first cousins, you really should seek someone who it would take genealogy research to find a common ancestor with. If you’re not, it’s still a serious risk to have kids with anyone too closely related, but level ramifications seem really harsh, especially thinking of situations like adoption where someone could end up there accidentally. And to your point, it isn’t the only way to end up with that kind of risk profile.