is it a good idea to fix your kids' cars for them?

I was outside in the garage with dad when I was a kid, learned at an early age how to do brakes, carb rebuilds etc at an early age.
I remember when I was 16 and tore the clutch out of my first car 65 coronet.
Dad said, I am only going to show you how to do this once....

My youngest son is 13 and him and I are rebuilding a duster for his first car, he is really good at brakes and aligning sheet metal.