I grew up with five cats in my household since I was about three years old, and tending closely to a few dogs since I was five.
I can honestly say though that having been close to as many animals since then, it wasn't a helping factor when I joined the Fandom in '05. It was actually that year that I had suffered a violent attack from a dog, and didn't want anything to do with them, or most other animals.
To be fair, I think that a better theory is that "If you've had close relations to "x" animal, then that may be why when you joined the Fandom you chose the same "x" animal as your fursona, because you feel so close to it/have experience with it/etc." As an example, ever since I got to own a German Shepherd for a month, as part of a test to see if it would work well in a home (The Monks of New Skeet here breed and sell German Shepherds, they often place them in homes to see how well they can get accustom to home life), I've always wanted one. Thus, that's why I chose a German Shepherd as my fursona.