I was able to rip stuff apart and put it back together at a very early age. My dad owned a couple of laundromats and the coin mechanisms would screw up, he'd replace three or four, bring me the old ones and I'd rip them apart and make 1 or 2 good ones out of them. I was5 or 6. My dad still talks about that.
Around that time, my dad also bought us a minibike, one of those lawnmower engine things. In fact, Toyman has one that looks almost exactly like the one we had. Anyway, the damn thing stayed broken so my dad and I would hoist it up on the picnic table in our back yard and fix whatever ailed it. My dad still talks about that, too.
I graduated to motorcycles when I was about 11 or 12, but I did 4 strokes. So I was reringing top ends, grinding valves, etc on my own by then. I was splitting cases and replacing transmission gears etc too. That was SCARY the first time.
That's when I started racing motocross and man I LOVED MX. I quit with it for a while when I discovered girls and later beer. Sometimes I think I'd have been better off sticking with the MX.
I got my first car when I was 15 (a 1965 Ford Falcon Futura) and of course it was slap worn out (hey, even in 1974 $225 did NOT buy a lot of car). I knew motorcycles pretty well but not much about cars but if I was going to roll I had to wrench. So I learned first hand about clutches, manual transmissions, fuel pumps, alternators, brakes, suspension stuff etc because it was all just plain worn out and I replaced stuff as I got a few bucks. And man did I make some mistakes. One memorable boo boo was when I decided to put a floor shift in the Falcon and 'eyeballed' the floor pan hole, turns out I cut it way too far forward.
When I told my dad, he said "Measure twice, cut once'. Smart ass.
I got a 1968 Triumph Spitfire a few years later and thanks to it I learned a whole different way of looking at cars.