When I was 5, I borrowed the adjustable wrench and somehow managed to remove the training wheels off my bike. (w/help from dad) Then I went to all the neighborhood kids and tried to convince them to let me do the same for them. Even today, I'm a better mechanic than I am a salesman.
I think it takes a love for things mechanical along with that certain talent to be patient and work things out before actually doing them. And the willingness to learn and make mistakes.
55/Rad