As far as I can remember I've always been into tickling, as most people here. I think my oldest tickling-related memory involves the druid Getafix getting tickle-tortured in Asterix the Gaul. I wonder whether here in Europe that scene had the same influence the TMNT or Popeye had across the Atlantic.
Growing up I was both repulsed and fascinated by the nastiest aspects of history, as they were presented in books such as "Horrible Histories" and the like. I've always been puzzled by the fact that we cannot tickle ourselves but one day, I might have been around twelve, I discovered that I could elicit a tickling-like reaction by fondling my private parts. Back then, I didn't know what that sensation was, as I was the naivest kid in the world. But since then I have never been able to dissociate tickling, bondage, pain and sexual pleasure.
I haven't had access to the internet until I was eighteen, and so I spent my adolescence thinking that I was one of a kind and no one else could have ever had such a ridiculuos fetish. Mind you, I was well aware that "perversions" existed: I remember secretly reading Henry Miller, Anais Nin and de Sade, and getting increasingly disappointed by the fact that, amidst the debauchery practiced by those libertines, no one ever thought about something as innocent as tickling each other's feet. I start writing stories and even drawing some comics that would constitute the fundation of my brand-new perversion (I later destroyed them all). Obviously I didn't dare tell anyone about it, and especially not to my girlfriend.
Everything changed the day I googled the word "tickling", and among the many innocent results I got the link to a video on youtube. The story told in the video was simple: two roommates are arguing because one of them has stolen the keys of their flat. Thus, the other one has no choice but to tie her up on the sofa and tickle the whereabouts of the keys out of her (I later discovered it was an old video from FM Concepts).
I cannot say that everything has been fine and dandy since then, but that was the moment I learned I wasn't alone.