Even though I'll be lampooned for it by the "new" furries, I truly believe the rat chose me, not the other way around. The more I reflect on it, the more honoured I feel by that choice. (For full disclosure, I should admit that Mrs Frisby and the Rats of NIMH and Roland Rat were very big with me during my formative years, but that could just be the chicken and egg debate in fur.) It makes perfect sense: Who would want to be a rat? Rats are small, insignificant and reviled by Western culture. A rat acquaintance told me he was attracted to rats by their status as an iconoclast, but I don't think I ever sought out controversy intentionally. As far back as I can remember, long before I discovered the furry fandom (and, yes, probably even before NIMH and Roland Rat) I was attracted to rats. I thought they were cute (in spite of Western conditioning) and admired them for their intelligence and belligerent determination to live (here I owe a debt to a Christian TV preacher, one of my earliest memories relating to rats, who told the story of the family who tried to kill a rat that just wouldn't die). Which brings me to another early influence when it comes to rats: My father. He taught me to respect rats. He made a humane live rat trap, and I saw a rat escape from it once, by squeezing through a hole the size of its head. It gave me the willies at the time, but it showed me how determined rats are to live. He also told me a story (which I strongly suspect to be apocryphal) of how rats steal chicken eggs: One lies on its back and holds the egg with all four legs while the other drags his friend by the tail.
So the short answer is that I don't know. I could have just said that, but I wanted to be more honest than that, and to also lay out the early influences as I saw them.