Opinions divide, of course. But for most it's a choice. I wouldn't go so far as to ascribe my furry-interests infantilistic urges. It isn't rooted deeply in my psychology. It's just something I'm really into. For me it's an artistic fandom I grew into while learning to draw. That's why I had a choice when it comes to my fursona too. However, I never sat down and thought about it. It just was Kuzzy, lion from the beginning. So it's hard to tell whether it's a suppressed feeling (lion king, I tell you) or just a random thought.
for me it started as wolf because i have such a love for them and slowly over the last 2 ish years has grown and changed. i think for some people it's something that slowly evolves for them as the years go bye, i know sulli is not perfect yet and there will be some changes soon. but for now he is as you see him on the side. just as the years go bye and RP start and finish i add little stuff that feels right for him. just one of those thing that keeps evolving over time.
My chat fursona evolves through rp, and exploration with other fur rp-ers. I feel liberated to try things through him (ie /ME) with my new appearance, and with your furpearance... (fappearance?) - without concern for gender, say, or your rl shape or my own... with fur-on-fur although we have fur-genders it does not seem to matter: it is raccoon-on-wolf (or fox) not guy on guy, or guy on girl... for /me at least...
Minds are odd things. Discovered or chosen? Either, both... Both ways are sides of the mind. We will end up in a nature/ (self)-nurture debate... I choose to discover my nature, and mold it by allowing it to manifest, to grow, to change, to be crafted by my choices... The "allowing" is a choice.
Nuff for now. If you really want to get into nature/nurture I am game... but not now, not here. New thread perhaps.