I never had a helmet as a kid (41 now). My buddies and I did our own imitations of Evel Kneivel and never got hurt too bad either. Now that I'm older and wiser, My son has always and will always wear a helmet, as do I.
As a matter of fact, my son got "pulled over" by the cops many times and was given a certificate for a Happy Meal or a DQ Ice Cream for wearing it.
Now it's a habit for him.