What conditions do the inbred royal families have?

2 conditions: Some european royalty -hemophilia. House of habsburg -mandibular prognathism.

Hemophilia: Hemophilia is the most common such serious condition in european royalty. This particular illness did not become common because it--as opposed to many others--is specially associated with inbreeding. Rather, by chance it appeared in the royal lines and then became concentrated by intermarriage. In other royal families elsewhere different illnesses dominated.