If you can't write with your left hand, because you never learned to do so, and you can with your right hand, you're a right handed writer. That's the only form

If you can't write with your left hand, because you never learned to do so, and you can with your right hand, you're a right handed writer. That's the only form of writing you can do. Yes, the underlying handedness is independent of culture, but the actual ability is cultural.