At least for me, it's also a matter of the other person (or persons) involved in the situation. I have a submissive side, but it takes a very alpha male to bring it out, let alone to keep me under his control. Yet I exercise an appropriate level of dominion over my own boy, who is just starting his journey into submission. The tendency to acknowledge another's dominance is part of a natural hierarchy structure but developing it, and deepening it, requires nurturing.

So I guess I'm going to say it's a combination of nature, nurture, and circumstance.