User blog comment:B214/Volume 22 spoilers/@comment-201.215.165.7-20170213165134/@comment-1359322-20170214054745

Guys Reincarnated Devils doesn't just refer to the person that was reincarnated. It refers to the root of the ancestry. Ise's ancestry is of human not Devil. That's why his children with others like Asia and Akeno will be reincarnated Devils too because their ancestry aren't originated from Devil.

Think Harry Potter format. A child of two Mud-blood will still be recognized as a Mud-Blood not a Pure-Blood.