Ah, royalty. The word conjures images of power, wealth, the means to shape history, and . . . inbreeding? With so much at stake, royal families across the world have tried to keep the bloodlines clean and the seat of power firmly intact through strategic intermarriage. Ignoring rules of consanguinity may have kept various family members gainfully employed for generations. What’s the downside? (Aside from the inherent grossness, of course.) The overlapping of genetic material elevates chances of health and developmental problems, as well as murder and exile. King Tut’s many health issues—necrosis, a partially cleft palate, and stillborn children with his own sister-wife—are thought to be connected to his family tree, which looked more like a wreath due to generations of incestuous coupling. Perhaps the most famous example of the perils of inbreeding is King Charles II, the last of Spain’s Hapsburg rulers. The result of 200 years of intermarriage, Charles’s tongue was so large that he could barely speak, and his infamous Hapsburg jaw was so pronounced that he was unable to chew. The behavior that his ancestors chose to keep the crown ended up terminating their line instead. And there are a lot more where they came from.