User blog comment:B214/Volume 22 spoilers/@comment-201.215.165.7-20170213165134/@comment-31137559-20170213235958

The children of two devils will always be a pureblood devil. It doesn't matter if one or both of the devils weren't originally devils. So when Issei and Rias have a child, their child will be a pureblood high-class devil of the House of Gremory. And Issei's and Asia's child will be a pureblood devil because although Issei and Asia were originally human, they are now devils. I just wonder if their child would be a high-class devil. I wonder about the status of the children of reincarnated devils. I imagine that if two reincarnated devils have children and one or both are high-class devils, that the child will be a high-clasz devil. Not every reincarnated devil can get lucky and be engaged to a high-class pureblood devil from the 72 Pillars. I wonder what the status of Rudiger Rosenkreutz's children are(if he has any).