My dads side of the family have always worked on and raced cars, it skipped a generation with my dad and he had and still has no interest in mechanical work. So I had to do tech school to learn alot in a short amount of time, and a large amount of automotive skills easily translate to motorcycles so that was an easy jump for me. Would be a different story if I lived near my grandpa as I would've spent alot of time with him but we moved 1000 miles away from him when I was 4 and never really got to see him much.I learned when I was 6-7 years old watching/helping my Dad change oil, adjust valves ,grease the suspension on our 41 chevy+ we had a small machine shop in the cellar and I was taught to use a lathe & other machines properly. when I turned 18 and could get a real job I advanced quickly to Journeyman status from my early experience.
I did the same for my oldest son and he still make a handsome living as a CNC machinist.
I was lucky (although I sometime didn't think so )