child passenger

Hi, I have a question. What is the legal age for a child to be a passenger on a bike in California.
And I mean not on the freeways or the heavy trafic.
You see I have a 3 year old and whant to know if it's ok to get out infront our place and give him a ride for a five minutes. /it's a 15 miles zone/ I've seen that in europe recently /In Paris/ and seemed like the norm there. Also when I was a kid my dad used to ride with me placed in front of him. /I had a special little helmet with a peak that I was very proud of/
I know that many of you think that this is a heresy and the parent deserves to be publicly linched on a tree for such action, but when my wife told me the other day that when he picks my son from day care and they park at home he gets out of the car and kisses the motorcycle , saying : that's daddy's bike... I got deeply touched.
I also admit to have done a little bit of riding with him on a parking lot couple of times and he loved it... What can I say, I love my son the way my dad loved and understand me when I was little. That's why I also started very early on my dad's bikes.

current bike; gsxr 600 04