Hmm, well. The only kids I've ever seen at Metal concerts were an 8-10 year old in the balcony headbanging along with his father at a Hammerfall show, and a couple of 12 year old girls with her dad and mom waiting in line at a Stratovarius one.
On the other hand, age doesn't really matter. People generally behave stupidly at concerts; they are "Metal", thus they are rebellious and madly tough. :roll:
A friend had to knock the lights out of a dumbass at the said Stratovarius concert because the moron (along with other dozens of morons) kept throwing himself at the front, creating a wave that was crushing those in front, so my friend turned around and told the guy to stop that, the guy replied with something stupid and aggressive so my friend just punched him in the face, breaking the idiot's nose and making him black out. Hey the pansy got what he deserved.
On another ocassion, at a Joe Stump gig, security had to take out some dumbass who was looking for a fight, but it was nothing really serious.
It's sad how Metal music attracts so many idiots who don't care for the music or are there to have a good time, but who need to have an image of toughness that will cover up for their insecurities. :(
There are a lot of poseurs out there, I tell you. :D