My personal opinion is that very few are truly one or the other. Most biological and psychological variables follow a normal (bell curved) distribution with the majority in the middle and 'true' subs/Doms at either extreme. Most of us, even if we consider ourselves subs or doms, stray the other way even if only a little. Also, I do not think there are many who have not played on the other side for at least a short while. I am a sub but I still find subs who are more submissive than me. I have seen Doms who are more dominant than many other doms. Natural variation makes this distribution inevitable.

Identity will come if you relax and let it happen. Play around, meet people, talk to them, experiment with different things. See where your feelings take you and what feels right when you do it. You may be a switch or a sub or a Dom but you won't know at this early stage.