Interesting thread. Thanks you mastersgem for the OP.
I'm inclined to agree with GreyJack: the human psyche isn't exactly a simple matter. We start out with a basic mental mapping, and we use that set of directions to respond to and navigate through what life flings in our way.
In my case, the submissive urges and fantasies surfaced pretty early. They have (obviously) continued into the present. In my work and in my day to day life, I'm a pretty Dom and a pretty controlling personality. I look at my submission partially as a respite from the stress of that, and partially as a symbolic way for me to say to a partner, "my submission is a gift unique to you." Knowing what I know about myself now, I can take an educated glance back at my childhood and realize I felt a lot of pressure even then as I was a fairy mature and pretty bright little kid; and I wonder if the submissive desires weren't sewn into the mental soil then as a way to relax from that?
As for the turn this thread has taken in touching on abuse, again, we all start out hard wired a certain way and abuse of any type can have many and varied different results. It is true that A LOT of victims of physical or sexual abuse will seek out partners that are abusers themselves in a misguided attempt to be able to relive and correct the mistakes of the past. They feel that if they can change the course of things in the present, the wounds of the past will heal. Others will seek out a "safe" way to play through the trauma, i.e. a D/s relationship where the "abuse" is safe, sane, and consensual. In my case, something completely different still: in my mid twenties I began and ended a serious relationship with a man that had very Dom tendancies I was attracted to. We had been friends for some time, I thought it would be okay, but as soon as I was "his" the Dom tendancies turned controlling and I stepped ut of the relationship. Let's just say he didn't take too especially kindly to that and I ended up on the recieving end of a pretty spectacular beating. A few broken ribs and a black eye later, there wasn't ANYTHING subbie about me AT ALL. I topped in every relationship afterward just to grab back some semblance of my sense of control and safety. My relatinship with J-Go is the first since then that I've allowed the sub level of vulnerability back into my life.
One very long winded post later...There's no formula for a sub, no formula for a Dom. You start with a person's general make up, mix them with some life and see what happens. It is, however, a REALLY GOOD THING for both Doms and subs in a partnership to talk about and try and discover where they came from and why. It's all about communication and knowing each other and yourself.