There are two points I want to make:
1) It's interesting to see so many people conflating talent with skill.
So you've been painting for 20 years; you have developed 20 years of painting skills. You cannot develop talent.
2) Talent, as I see it, is merely an adjustment of the entry point in developing a skill. If you are talented at something, you can pick it up faster, i.e. develop skills in that activity faster than someone who does not have the same talent.
For example, I have a talent for algebraic organization.
I'm really good at modifying algebra equations in my head.
This does not mean that I am also innately skillful at Integral Calculus, or Trigonometry, or Non-Euclidean mathematics; I've still had to work hard to get good at those maths. What it does mean, however, is that I had a "leg-up" on my classmates in primary and middle school when we were working on arithmetic and simple algebra, and it has helped in learning the higher maths.
Now, to respond to the OP:
Yes, I do believe natural talent exists.
For your own sake, I will say that I believe parents are not 100% accurate in identifying "natural talent" in their children. If you do feel that what your mother is identifying as natural talent, is a proficiency for following rhythm that you've developed playing Rock Band, etc., is there another instrument you'd be interested in learning?