I have been a DL since I was about 12, now 39. I don't know if it was a specific incident, but my first memory of DL desires involved a dream about a neighbor wetting her pants while we were playing, and I remember the feeling it gave me. When I actually would see her, I would think about that dream.
I like to read the stories. My actions are more fantasy and entertainment than reality. I am married and have a kid, and know discussing this particular aspect with my wife is impractical (though I would like to see her in a diaper - she would be really cute!)
I have no desires to be anyone's daddy, to be anyone's baby, or to meet anyone to play. As long as you don't mind me reading the posts, I will continue to remain in the background. I might make a few comments or suggestions on in-progress stories, but I think everyone should express their own creativity the way they want to express it. There are some talented writers here!