Bred to death: The royal crest of the Hapsburg dynasty.
Credit: Wikimedia
Charles's parents were uncle and niece, but high levels of inbreeding in previous generation gave him an inbreeding coefficient more like the offspring of brother-sister or parent-child couplings, Alvarez said.
Two of the kings in Charles's ancestry married a niece, two married their first cousins, and four others also married biological relatives. Only Charles and one other Hapsburg king married women they were not related to.
Peter Visscher, a geneticist at the Queensland Institute of Medical Research in Brisbane, Australia, said that although it is impossible to be sure that inbreeding was the cause of the dynasty's end, Alvarez's team had shown that there were large inbreeding coefficients in the Hapsburg family.
"It would be nice to know what the inbreeding coefficients of contemporary non-royals were, but pedigree data for ordinary citizens that lived many centuries ago must be hard to come by," Visscher said.
