As others stated before, e'res nothing wrong with roleplaying a character whom does not have the same gender as you, Nyan. |D
This is all just roleplaying, thus there is nothing wrong with making any character of any sort- weither they are male, female, or simply an 'it', your gender quite frankly does not even matter in such case. It's more or less the same with writing books, really! You aren't going to make all your characters female because your female, right? It goes the same way with anything else!
And, if anyone thinks it's wrong to 'cross-gender roleplay', then that's their own problem, not knowing that roleplaying is like story-writing.
This is just about the same as roleplaying as a cat, but you aren't a cat in real life, really; only this 'al is based off of gender. ouo.