Ever try just asking them? Telling the how you feel?
A) Don't want you to get hurt/taken advantage of/heartbroken
B) They like you or are attached to you and don't want you to be taken from them.
something of the sort.
You might not want to, but it's time you got a clear answer so you know how to think of things/handle it all. Right now it's apparent it's bothering you because it'll continue to bug you.
They're dysfunctional and immature. Keep them away from your underwear and valuables & embarrass them for a change.
Lay down the law upon these insolent fools
I am more interested in what makes you let them do this...
What? are you a child?
I'm making a guess. Maybe one or both like you.
Umm, it doesn't have to be sexual to express fondness, and one can like someone one calls their "brother" or "sister", I mean, you aren't really.