Here is an awesome performance of a bluegrass instrumental, "Salt Creek," with Sierra Hull on mandolin and Ryan Holladay on banjo. You Tube doesn't say what year this is, but they look to me to be about 12 years old. We can see here an example of the enchanting phenomenon of God-given talent being heartily embraced and developed at a young age.
The maturity and confidence Sierra has in her playing at this young age is unbelievable. An older person with some musical ability (but not prodigy-level talent like this) could practice till they dropped for years and years and never come close to playing like this. It's a gift! But it doesn't come automatic. For sure, they must spend hours and hours practicing, developing this great gift to its fullest potential.
By the way, I highly recommend for any of these music clips that you plug in some headphones into your computer's audio jack before you listen to it. The sound will be much better and you will hear more clearly the nuances of the music.