As far as I can tell Sanae's odd, kinda insane behavior, is a combination of upbringing and her parents/guardians or Gods I guess. Suwako seems like the main influence, Suwako seems detached and calls the Aki Sisters 'original characters' or something like that. Kanako, well I don't know. She's the sanest one of the Family so far and she at least didn't berate or dismiss the sisters as far as we can tell. Kanako still seems a bit odd though.
Regardless I've been enjoying this and the others made by Uni Mate. This, Shangri-La and A Bright Future give me a real bittersweet feeling, fluff, and an undertone of sadness?