User blog comment:Dark Midnight Scarlet/Tsukinami's Birthday?/@comment-26076447-20150805024455

Carla and Shin have both lived a lot longer than the Sakamakis they are also older than Cordelia as well. I have a feeling that they do not remember their birthdays or Karl gave his sons actual birthdates so they could fit in with humans. Carla and Shin do not really have any intention of that. I suspect that they are slightly younger than Karlheinz. Rejet probably did not give them birthdates purposely as well.