moral-man's comments are interesting.. I have two things to say about them and then will consider my own thoughts on why I might be submissive.
1. I think moral-man is close to the truth - dictionary-definition-wise at least - regarding what makes something a perversion. I believe (could be wrong) that clinically, sexual fetishes are considered 'perversions' if they become the ONLY way in which someone can get sexual pleasure/satisfaction.
2. Having said that, I think it is off the mark to suggest that people who very much live out a dom/sub lifestyle are taking their sexual activities out of the bedroom in an unhealthy way. I don't think it is even unusual. After all, why do couples get together? Because they are sexually attracted and want to fuck one another. Isn't it taking that out of the bedroom when they move in together, buy furnishings, go to the cinema... they are living out a life entwined socially, basically because they wanted to be lovers.
3. I am generally baffled as to my own submissiveness. I wasn't abused. I have never been in a big, powerful job giving orders all day and therefore hankering to give up power for a change. I do seem to have an aversion to making decisions in general life at times... but since I have had submissive fantasies from a very young age, I can't really link it to adult personality traits that I have developed. Perhaps it's something to do with parents (who were very liberal), heave only knows....