I determined that I had an interest for female feet -- particularly, looking at them, touching them, and tickling them -- in my early childhood.
I can't remember NOT having these interests!
It wasn't until I was age 15 that I realized that these interests were actually fetishes.
This was 1988, and I wanted to learn more about what a fetish was.
Of course, the Internet did not exist then in the way it does now... but libraries have been around for a long time.
So off I went to the Coral Gables Library (I grew up in Miami FL), and I read all kinds of books about sex.
Alfred Kinsey, Shere Hite, and Masters & Johnson were some of the early sexologists that authored the books I read at the time.
Each sexologist had something to say about fetishes in general, and the foot fetish in particular: it all boiled down to "different, but basically harmless."
I don't think I read anything from any of those sexologists about the tickling fetish.
SIDE NOTE: growing up in Miami with a foot fetish was both heaven and hell for me. Put simply, it almost never gets cold in Miami. That means people will wear open-toed shoes ALL THE TIME. Enough said?
By the way... when it does get cold in Miami, it goes down to 60 degrees Fahrenheit for a day or two. Some years, it will last for a week. Once in a blue moon, it will dip into the 50s. The last time it snowed in Miami was 1977 (the winter before my family moved there) and it was only a dusting. No accumulation. Which was good, because there are no snowplows in Miami.
In my youth, I owned no coats, jackets, sweaters, sweatshirts, sweatpants, longjohns/thermal underwear... need I go on? I can truthfully state that the number of times I wore multiple layers of clothing in my childhood was less than ten.
Growing up in the Magic City was amazing, different, eye-opening, and unique. I wouldn't trade it for anything. I love being from Miami -- what an extraordinary international city... with the worst traffic on the planet.