Well, in my playthrough MC's mom is dead (killed her myself irrc). And +12-15 years (or however far the canon supposed to be, as the usual silly +18 years is probably for censorship circumvention purposes) she'd be like 70yo+ anyway. So MC not fucking the mom. Mostly just his kids and grandkids so far (and optionally that blind girl). Not so much the kids anymore though it seems, other than Savanna (the most perverted of them) it seems they don't like Daddy that way anymore after being gone so long looking for his sister (for now? India did kinda relapse and regretted it after, same for Alison).
I'm assuming that while his OG daughters being upset with him for being gone so long is likely a part of it, I have a feeling it's more about the Priscilla secret that they're all working on, the mistrust of him
actually being home for good, and somewhat them being torn between going back to what they had and being afraid of subjecting their own kids to the same childhood (and potentially whatever secret Lillith told India at the very end of The Guardian when it comes to her in particular, assuming she never told the other sisters about it, based on the endings of that game, it seems like she *specifically* locked herself off from MC early on and "always seemed to know something about Lillith that she wasn't telling [the MC]").
My guess is that they will all end up back in (potential) sexual relationships with the MC eventually, but not until the plot moves forward a bit and all of the secrets between everyone start getting revealed. Based on the way the first release ended, I can't imagine the Priscilla secret is going to have to wait too long before
it gets explained, considering what just happened, so hopefully that will start things moving in the right direction.
And as for the mother, even if the MC doesn't kill her, and opts for the "give her a chance at trying to redeem herself" at every opportunity, she ends up being killed in the end by one of Father's people, I forget if it's Beatrice or her Mothert that comes to her, or if it's just some generic goon, but they give her the option of "death or 'the chair'" and she chooses death". We don't actually see it, but it's not in the questionaire at the beginning of TLG, so I presume it's canon she's dead. I believe in the "Lola's future" in TG, Erica has her ashes in an urn at her house, but those seem to only be somewhat accurate to the TLG canon, so who knows. Not like other characters haven't "come back from the dead" in the Seath-verse. But yeah, even if she's somehow alive, she'd be really old, so definitely not on the fucking block.