Let me share with you a VERY wise golden rule, and it is this: one family member per customer. ONLY.

In other words, no. It is neither sound nor kind to literally put your fingers in every member of a family, because when it all comes to light -- and it always does -- it really can mess up their relationships, which they don't get to just walk away from like you can, and that is seriously uncool.

It is developmentally normal for young adults to be less selective about sexual partners than their older counterparts. It is. It is also normal to be unsure how to deal with boundaries and where to make them. It is ALSO normal to try and stay within a certain comfort zone with people you know you're comfy with. Sounds like you've got all of this stuff going on right now.

But you're crafting a Jerry Springer episode here, and one that is really unkind and inconsiderate to the whole family. Flatly, at this point, I'd suggest you date (and have sex) elsewhere entirely. Because really, I think you may well be looking for an arena to explore sexuality in that feels safe and "home-like" to YOU, but it's destructive for everyone else, and likely to end up with you having NO relationship, even friendships, with any of these folks.