In all honesty, you shouldn't put too much thought into this. Maybe keep a spare razor in the bathroom and let her know it's there if she wants it, and make sure she knows how to use it safely. Things like waxing and Nair are too tricky for a young girl, IMO. No need to talk about drastic measures like electrolysis unless she develops an amount of hair that makes her uncomfortable.
8/31/12 at 6:07am