It happens. I can play hockey with either hand as dominant. Too bad that wasn't really a useful talent like being a switch hitter in baseball. I'm generally left handed, but play musical instruments almost exclusively right handed. I had a friend teach me drums. He was right handed and didn't even think to ask me about my handedness, or didn't want to move stuff around (lefties have to adapt to a right handed world...). It didn't feel awkward though. I don't know why I play guitar right handed. The prevailing theory in my family is that I "learned" by mirroring Kurt Cobain on the TV screen...