Who is Newt from Lonesome Dove and what is their importance?

Newt Dobbs has been with the Captain and Gus since his mother passed away with the fever. They took him in, knowing it was the only Christian thing to do, as he had no where else to go. He has always wondered if Jake Spoon is his father, but no one would ever confirm it. He's been told that his father was a man who went west at the wrong time, and that was the last anyone saw of him. Newt doubts the story as no one ever speaks of a Mr. Dobbs in any other tales.