First cousins are in a bizarre legal sweet spot. They’re not in the “close family” ban list, so go ahead and rent that church. But double first cousins—where both sets of parents are siblings—are still just cousins. The law shrugs and says, “Sure, roll the dice on genetics.”
Why is this allowed? Historians say it’s because your average first cousin shares only about 12.5% of your DNA. That’s not zero, but it’s not “let’s invent a royal dynasty” territory either. Plus, back in the day, marrying your cousin kept the farm in the family—literally.
The “But My Genes!” Panic
You’re probably imagining children with three arms and a sudden love for banjos. Relax. The risk of birth defects for first-cousin couples is only about 1.7% higher than unrelated couples. That’s the same bump you get if the mother is over 40 or the father has a questionable beard.
Still, your GP might raise an eyebrow if you announce your engagement to Cousin Becky. They’ll likely suggest genetic counseling, not an exorcism. And if you’re both healthy, the chances of a “Royal Targaryen” baby are laughably low.
Can You Marry Your Cousin In UK? - United Kingdom Explorers - YouTube
