I consider myself to be masochistic, and I'm not really sure why I am the way I am in that regard. From speaking to the folks in my BDSM community, I think it's at least in part hereditary. One of my friends has a sub whose children (they are 8 and 10) love to be tied up. Another lady I know loves to tell the story of the time she found her 5 year old son straddling the bath tub and jumping up and down crushing his nether-bits and giggling. I'm adopted, so I have no idea whether or not my tastes for BDSM are hereditary or not, but I think it's an interesting concept.
That said, I had a blissfully happy childhood, aside from being teased at school. The only really bad thing that has happened in my life is my dad died of brain cancer when I was 18. I've dealt with depression on and off since that happened, close to 10 years ago. I don't recall showing any leanings towards BDSM as a child, but my memory is also crap. I first became interested in kink when I was in my early 20's, but didn't find a partner who was into it until a couple years ago.
I like to think of myself as a moderate kinkster. I like knife play, as long as it doesn't break skin. I like scratches, hair pulling, spankings, flogging as long as it's with a stingy flogger as opposed to a thuddy one. I also like light choking. I enjoy feeling the restriction of my breathing, but not having it gone completely. I find the surrender especially intoxicating. Trusting the person I'm with to take care of me, and not harm me while hurting me is just an indescribable feeling. Having them physically lead me to do things to them, or being tied up and letting them do whatever they want to me is just awesome. Candle wax is fun too, but honestly that just tickles more than anything else.
If my kinks make me screwed up in the head, so be it. I will say this though. Becoming a part of my local community has helped me out in so many ways besides just giving me an outlet to explore kink. It has increased my self confidence and my comfort in my own skin. It has also helped me make a bunch of new friends over the last two years, that are just truly awesome people. Also, in my community at least, there is a huge overlap between kinky, geeky and polyamorous folks. It's amazing.