Rebel Wilson Says Straight Actors Should Be Allowed to Play Gay Characters

Rebel Wilson's blasting the idea of determining casting by sexual orientation ... saying straight actors should be allowed to play gay characters and vice versa. The actress sat down for a chat on BBC Radio 4's "Desert Island Discs" -- a talk show that includes music the celebrity guests find personally significant -- when Rebel's sexuality came up. The funny woman reflected on edgy jokes she's told in the past,…