From the most powerful royalty in history to an uncontacted village in New York State, we're talking about some of the most inbred people of all time.
The Blue Fugates of Kentucky were an isolated group of settlers who, through a rare recessive gene, developed blue skin. Due to their blue skin and their isolated location, they began to inbreed, eventually becoming something of a local legend - the blue hillbillies that live in the woods - until they reappeared in the 1960s.
Allentown, New York, is a village in New York State that was cut off from the rest of society after a dam flooded the valley where they lived. They call their community The Hollow, but outsiders call it Allentown because almost everybody there is from the same family.
The Habsburgs of Europe were one of the most powerful families in history, ruling over the Holy Roman Empire in Eastern Europe until the early 20th century. But one segment of the Habsburgs in Spain, known as the Spanish Habsburgs, participated in incest and inbreeding for so long that they developed The Habsburg Jaw - a genetic deformity that got so bad that many could barely speak. It was Charles II of Spain that finally put an end to this practice because he was so inbred that he couldn't reproduce.
And the Egyptian royal family of ancient Egypt practiced inbreeding for over a thousand years because they believed that the only person who could mate with a pharaoh was someone else from their family - they were living gods after all. By the time King Tutankhamen was born, their lineage was so ruined that he had multiple genetic deformities and died at only 18.