How do you know if someone has "Natural" ability for golf?

Question

Hey all, I have a brother who is only 22 years old. He's been playing for 2 months and has had 2 lessons. He went from a 15 handicap and shot an honest 5 last 3 times we went on a pretty tough course.

He really want to try to make the PGA Tour, but is really discouraged since people say he is too old. But having natural talent is something else. I've never seen someone improve that fast. What do guys think, should he pursue PGA Tour goal or what?