I made up the age and she is making up every rule that accompanies it.
Exhibit A:
Notice anything wrong with this picture?
Did you notice the little strap by her shoulder. Yep. That would be a bra.
She is five -- many, many years away from even a whisper of a need for one. That doesn't matter to her.
We were shopping recently and as she was walking her confident, swanky strut in front of me I looked down at her and noticed her t-shirt slipping to the side of her shoulder, revealing a little strap. I did a double take. Was I seeing what I thought I was seeing? I stopped her and quietly had to ask, "Eliza, are you. . . are you wearing a. . . a bra?"
"YUP!" (at her usual volume of 100) "I got it from Eva's drawer and put it on last night before I went to bed." Said as just as matter of fact as you can get.
"Oh," {turn head and surpress laughter} "ok." If she was confident in her decision to dress herself, then I was not going to burst her bubble -- at least not at that moment.
Luckily, the answer is easy. Nothing. Absolutely nothing. Not when she has the love of 100 children all crammed into her little bra covered heart.