A paint could be a great jumper. As the above poster said, it depends on the build and the mentality. When you say young, how young do you mean? It isn't safe to jump a horse that is younger than 4, and it is best to wait until they are 5 or 6. You don't want to injure your horse!
It might be a good idea to post some pictures of her so that people can get a good idea of her build. When it comes down to it, any horse can do any discipline in the lower levels. She might not be a grand prix horse, but she might be able to safely take you over 3' jumps.
If you are going to start training her to jump, I would recommend getting an instructor or trainer out with you so that you don't push her too hard. Nothing like starting to do something fun only to push it too hard and end up not doing anything for a month!