User blog comment:B214/Talk About What You Want! 3/@comment-5.36.176.7-20150428165245/@comment-24098614-20150428211405

The problem with the Angel side of having kids is the little problem of Irina turning into a Fallen Angel because when sex is involved the normal thoughts of someone include lust, and that is a major sin to a Angel, and Issei even though has toned down of being perverted he can't help himself but be dominated by perverted thoughts.

The process of creating children with Angels is extremely challenging if this was a normal person that isn't that perverted it could be done easily but you are talking about Oppai Dragon here who thinks about lust 24 hours a day, and his thoughts are so pervy that if he was a Angel he would have to monitored 24 hours a day on his thoughts alone.