by all means get the kid on something. A tractor, riding mower, motorcycle, anything with wheels and an engine....
My first experience on two wheels was with my uncle on a yamaha 175 at about 7 years old. At 9, I was running a briggs and stratton mini-bike.
You have the power to shape future generations, and a quick trip up and down your road will go a long way toward rearing a healthy, well adjusted young adult.
From the past:
'84 883 Sportster
'76 CB 750