There can't be any incest if there's no sex.
There is something very strange about the Jill and Bella path's in this game. If you try to do a playthrough where you purposely ignore J & B and/or intentionally fail every RP, by the end of episode 5 you are right where you would be if you had tried your best to get every RP. You still have a date with Jill, she still laugh's at all your jokes, and your still doing yoga at Bella's house. I don't know what's going to happen with these characters, but neither does anybody else.