I would say that 95% of the sculptors that I've talked too have all been self taught ... and/or been given lessons by or encouragement from other sculptors.
In so far as art background goes, being able to draw does make certain things easier, because it gives you a sense of scale and anatomy. Sculpting (to me) is basically drawing in 3D, with whatever medium you choose to work in. That being said, no one is born with an inherit ability to draw or sculpt, true some learn it faster than others, but everyone has to learn. The one thing you have to be is observant, keen powers of observation will serve you more than any class. While you may not always know how to correct something, knowing when something looks wrong is more than half the battle.
There are some artists and sculptors that will use the excuse "well that's my style" ... and while stylized drawing or painting is fine ... stylized sculpting is a little more difficult to pull off, especially when you're not paying attention to proper proportion, and you use a you use "style" as an excuse.
My advice ... learn to do it right FIRST, then experiment with different styles to see what emerges.
You can learn to do anything you set your mind to ... don't make the mistake of letting anyone tell you otherwise.
If you want a REALLY great resource book ... get Tim Bruckner's book "Pop Sculpture", it's got a lot of great technique information regardless of the subject matter you choose to sculpt.
http://www.amazon.com/Pop-Sculpture-.../dp/0823095223
Now grab some clay, sculpty or wax and make something!