In one of my projects, two of my team mates were in their mid forties. One of them was a mother of two (pointing this out because she didn't have lots of free time to learn new stuff). She didn't know Java, but she was probably a million times smarter than the rest of the team (4 more people, all in their early to mid twenties)
combined. She didn't go to college, while the rest of the team came from pretty good schools, with good grades etc. Yet, she picked up things faster than any of us.
So yeah, some people are just sharp by nature - just like some people are cute, strong etc (not saying others can't develop, but it does give the "naturals" an advantage)