User blog comment:B214/Volume 23 discussion blog/@comment-31764731-20170818183934/@comment-30924344-20170821094010

Issei's Children:

Ex: Half-Blood [Devil/Dragon; Issei no longer has his human side]

Robertina: Half-Blood [Devil/Dragon]

Zen: Third-Blood [Devil/Dragon/Human; 34% Devil, 33% Dragon, 33% Human]

Helmwige: Third-Blood [Devil/Dragon/Quarter-God; a half-god having a child with another species makes their child a quarter-god]

Kurobara: Third-Blood [Devil/Dragon/Nekoshou]

Shirayuki: Third-Blood [Devil/Dragon/Nekoshou]

Ernestine: Third-Blood [Devil/Dragon/Vampire]

Airi: Third-Blood [Devil/Dragon/Human]

Shin: Quarter-Blood [Angel/Devil/Dragon/Human; 25% of each species]

Kurenai: Quarter-Blood [Devil/Dragon/Human/Fallen Angel]

Simply put, the children will be classed as Devils with mixed heritage.