I think make up and hair color are related but orthogonal issues. Both are about identity, but makeup is much more about a gender normative, sexualized version of identity... while colored hair or piercings, etc are about a rebellious, counter normative version of identity. Personally, I would sanction or mildly encourage the counter normative expressions while being suspicious of the mainstream sexualized versions in a tween. I wouldn't ban either of those in junior high. Either way some discussions about identities and their consequences seem in order.
