Oh so it's like Harry Potter but actually good. Huh.
Honestly I get the impression she's really neglectful of her children because of her duties as lady and I think she's the matriarch running the entire show, so the affairs of her kids is something she's pretty much clueless about. Hell, Viola sneaks to see her brother even if she's technically forbidden and Walter's been fucking around with witches and demons and she doesn't know.
She really isn't involved in their lives so it makes sense she'd probably not care. Hell, I don't think they all even live together all the time, they might just be on separate estates.
@leti456