User blog comment:B214/General Discussion/@comment-1359322-20161106045332/@comment-9595671-20161108194854

And we only know the mothers of 11, Le Fay's son was mentioned but he didn't join the others, he may have been too young though.

No, he didn't scar his children that way, he can barely see them as is in the Ex timeline. That was just the assumption they all made from their mothers' all having big breasts.

I think it was mentioned Ravel has to do that since she's his manager, and we know so far atleast one of those other 9 children is likely Kunou's since her moving into the Hyodou household is pretty much confirming her for the harem, and Vol 23 may lead to Elmenhilde doing the same depending on if she joins Issei's peerage.