Responses
Over and over again, "purebred" seems to refer to being of nobility/royalty, not necessarily staying within the imperial family. So I don't believe in-breeding is what they wanted, so to speak. Maybe they'd marry second or third cousins since that doesn't affect the bloodline nearly as much as it would with marrying a sibling or first cousin. I could be wrong, though. Just sharing my thoughts.
Makes sense. Thanks!
Happy to help.
Are the other children of the king the result of inbreeding? If not, then I do not understand why the twins are not pure blooded.