I would say I have developed an appreciation for more genres as I've gotten older. Over the past year I've been listening pretty obsessively to soundtracks, for example. I've always appreciated some video game soundtrack composers ever since I first heard them but for a long time I wouldn't really go out of my way to listen to anything outside of the games themselves. Several years ago I finally did start listening to soundtracks outside of the games, but I didn't really listen to anything other than game soundtracks. Lately I have been listening pretty obsessively to film and especially television soundtracks (it doesn't hurt that television soundtrack composition has improved vastly over the past decade or so, in my opinion).
I've always had at least a casual appreciation for most genres, but really my interest in most of them ebbs and flows. One year I'll listen pretty obsessively to alternative rock; one year I'll listen to a lot of hip-hop; one year I'll listen to a sizeable amount of jazz. The only two genres that have been constant large presences in my listening for close to a decade have been metal and prog, and I doubt that's going to change anytime soon.
That said, my favourite band has been Godspeed You! Black Emperor pretty much constantly since I first heard them nine years ago, and that is also something that's unlikely to change. My second favourite band, if I can ever even name one, varies widely depending on my mood.