personally I'm not comfortable with bringing children into headshops. I figure it this way, with all the trouble that headshops could face from law enforcement (in the U.S. at least) its best to keep a strict professionalism when going to headshops. My three basic rules are these:

1) Don't EVER mention cannabis to anyone while inside the headshop or in the area directly outside the headshop.
2) NEVER refer to a water pipe as a bong.
3) Don't go to a headshop smelling like you just came out of a 4 hour smoking session in your car.

Also, most shops only allow people that are 18+ to even enter the store (at least around where I live and out in San Franciso (in the nicer shops that don't sell crack pipes). Personally I view headshops like a porn shop (at least until cannabis is legalized). You wouldn't bring your child into a porn shop would you?