Our walkers are over 18 and some do bring their children along but they are not allowed to walk the dogs. What we tend to do is take a couple of our own dogs along, steady greyhounds that are already in homes, walk beautifully and are very well socialised the kids may be allowed to walk them but the parents have to realise its at their own risk and the owner of the dog likewise.
The only two under 18 that have any dealings with the Gap kennel dogs are my son and his girlfriend 16 & 17 respectively and they have both been told that if they a) ever let go of a lead I will throttle them they hang on even if it means they hit the floor and b) if the dogs bite them they will be euthanised not the dogs because it will be there doing
That said again both are experienced with hounds as they have had a crash course spending all their time with me and are more sensible and able than some adult walkers. They are still not allowed near the newbies though that are under assessment.
I have had people bring their children to the kennels and they get giddy and excited when they are old enough to know better. I dont beat around the bush with either the parent or the child at this point as to what is acceptable behaviour!