Well this is an interesting study!
I also fit into the "other" category. You see, I've had a keen interest in diapers since I was 4, which is about as far back as clear memories go for me. I suppose this means that my DL bent has something to do with something which occured in my infancy, although I can't imagine what. Also, for some reason I was only interested in disposables, never cloth.
I didn't become at all interested in AB things until after I had first learnt of them as a teen (online, incidentally). At first "infantilism" didn't interest me at all, but gradually became more appealing over time. I can't attribute my AB interests to my childhood, good as it was, and must assume that they naturally developed from my love of diapers. That's as good as I can do, and I hope our answers will quench your thirst...FOR KNOWLEDGE!!!