I think i remember readin something on this. This is part of an article i found.

"Right brain/left brain dominance is a preference, not an absolute. No one is totally left-brained or totally right-brained. You have a dominant hand, dominant eye, and even a dominant foot. But dominant doesn’t mean you hop on one foot or do everything with one hand — it just means that when you’re asked to do something new, your body instinctively selects which side is best equipped to take the lead."

So basically your body and mind will instinctivly choose which is better to do the task at hand.