What would you consider an appropriate heel height for a 12 year old?

My daughter is 12 years old and wears 3 inch STILETTOS to semiformal dances. I wish she'd wear flats or at least wedges but she insists. Her friends don't even wear heels, but she says that's only because none of them can balance in them. She can walk in heels and hasn't fallen down yet but I think they are way too mature for her, regardless of where she's wearing them. I will say that a lot of other girls wear very high heels to dances including some nice girls my daughter has semi-befriended but still.