In ancient war times when countries had kings, it wasn't uncommon for 8 year olds to lead armies. 8 year olds in other countries are raising their own crops. 15 year olds were shagging other 15 year olds and raising children just a few hundred years ago. 10 year olds were reading 600 page books on logic in the 1700s.
Your kid is not a fucking thin sheet of ice. He should be walking, talking, and behaving like a man by 10 years old at least. Edit: One more thing, when I lived in Georgia during hunting season, every newspaper covered at least one story of a 5-6 year old taking a 10 pointer with a compound bow. That's not 100 years ago that's taking place today.
I went with my father shooting, and at 10 was cleaning the guns, and taking them apart, and putting them together. My first gun was a 22. I was use to the noise, the recoil, and knew how to take care of it.
Teach your kids how to fix things -basic electronics and motors. The girls too, they will be building things and 'inventing things as teens'