First off, my mystery asker, I dunno who you are, since you submitted the question anonymously.
To your main point though... it feels strange to say, but I've kinda always been into it since I was a kid. Unlike vore when I finally discovered that, I just kind have always been into it. Nothing specific jumps out as the thing that got me into it but I don't doubt a lot of things subtly have encouraged it more overtime, from say seeing Bugs Bunny's paws on Looney Tunes one too many times to that one scene in From Dusk Till Dawn. But I'm pretty sure I got the podophilia chromosome or something.