Yeah, the implication that because your brother might be gay means that he's the one taking your stuff and using it for perverse purposes is... yeah. Not cool, op.

Other than that, I think it's far more likely that it's your mom just taking your stuff to clean it or just snooping around and moving your stuff. Or, like >>5 said, your brother might be taking some of it just to wear it. I would ask him if he is taking your clothes, and if he denies it, just smile and say "Ok, I just wanted to ask you, because I hate that my stuff is going missing and coming back and I wish who ever is doing it would stop." so that if he really is taking it he knows he should stop.