No kids of my own but this question will arise for me in the next decade or so!! I think raising them around bikes and involving them, to then crush there dreams of riding one will hurt them, maybe even want it more, I plan to break them in on dirt, then ride with them and have them watch and learn, I won't encourage stupidity but I will have to let them get wild now and then like we are all guilty of. I plan on having that my dad's my best friend relationship. I I think not only showing them and riding with them will create a stronger relationship but they can learn when and were to be stupid I rather teach them to be stupid the smart way.
Maybe a year of riding with them no passengers aloud on there bikes, and yes I'll even be the cool as dad to ride with them to the movies and ditch out before there friends see me!