She's got nude sprites and there's a running joke about how there could be a true mom route from her point of view with scenes of her having sex with her husband, but she's not ever going to have incest scenes, nor will there be any in the game.
The most erotic I think the mom route would get would be cutaways to Z hearing their parents have sex at night and one walking in on the other while changing with some awkwardness and Samantha making a snide comment (to hide being upset her kid has bigger boobs than her) about how her son daughter has to watch their weight now with that thin waist or else they'll have to buy a second new round of clothes.