That is awesome congrats Dave! I've got three, one boy, and two girls. My oldest (boy) who's now six, almost seven races every weekend. He started when he was five with a Honda CRF 50 on training wheels. After he "mastered" that and started racing I moved him up to a KTM 50 SX. Start him young, going to the track with my boy is great. It's wonderful to see how much they'll start loving the sport, not to mention how proud you'll be seeing your boy out there doing jumps...LOL
I agree with bordguy, you'll defiantly go through all the stages of fatherhood...LOL One minute you'll be laughing your ass off at him, the next you're pissed because he decided to write all over the walls with a permanent marker. Oh wait, maybe stuff like that only happens to me...LOL