User blog comment:B214/Volume 21 info & spoilers/@comment-64.237.225.232-20160329204304/@comment-4547267-20160401163522

Also, if you think about it, the kids barely talks about their mother, just Asia being a wonderful human being and amazing aunt/mother. So in a way, they favor Asia over their actual mothers lol, maybe that's why they understand Issei problem XD