On the sister?
Just the pornstar/dog route.
On the mother, it makes her an absolute slut that winds up having no choice but to work in the company, where she has sex with many men, with the PC, and pretty much becomes the go to "instrument" for breaking and training in the Pit.
So far, they're the only ones it can be used on, but because it causes such extreme results, it's another case of how far we're willing to push against moral/ethical standards/boundaries. Which is pretty interesting from both a role playing perspective and a personal one.
We're able to push the mother and sister into incestuous relations with our character and each other, (granted they already have those inclinations), and then be able to push them even further into the extremes, despite all the warning signs of how badly things could go. After all, our character is working for a company that specialises in human trafficking and the creation of sex slaves through chemical alteration of brain chemistry.
It really all comes down to how "monstrous" we're willing to play our character as.