There is a band from Cape Breton Island called Slainte Mhath. I don't think any of them are twenty yet and the majority are still in high school. Two are little brothers of members of the Barra MacNeils. They have a web site, the URL of which I can't recall, but if you search under their name they should show up. They have a CD of traditional music out.

Fiddler Richard Wood from PEI isn't twenty years old yet, and he has four CD's out and has toured North American and the UK and Ireland. He recently played Letterman and GMA with Shania Twain, although he is mostly a traditional Celtic style fiddler and step-dancer and not a C & W performer. (Oh well, we all have to eat.)

Locally, there is a bluegrass band that has a 13 year old banjo picker, although he usually has to give their bar gigs a miss.