stepmom????...........no!!! I'd never do that to my dad, that's fucking scumbag. Stepsister???............if she was hot and wanted it..........hell yeah, no question. Like citrus said, it's a no lose situation. You aren't blood by any stretch, legally you can marry her, so why the fuck not?? Better do your damdest to keep it away from the folks though, that would probably fuck with their heads. But damn, what a setup!!!! You could try shit out on her first..........she could try shit out on you..........you'd be like each others training partners, outstanding!!!!