Like I said, beauty is in the eye of the beholder. Beauty is a fairly subjective topic. What is beautiful to someone is not beautiful to another. Some people like Elsa's external beauty. Personally, I prefer Ana, but this is also heavily influenced by her personality. See where this is going? It's not a red herring, because external beauty is often heavily influenced by other externalities (personality, voice, morality, etc.). And like I said, you can always plead ignorance if you're put up against a wall, but I think most parents are craftier than that. Turn it around by asking her questions. "Why do you want to be pretty like Elsa when you can be pretty like [insert her name]?"

You could also go the route of “well you can still grow up to have a hot body and some guys will not care so much about your face if you end up with nice tits or ass.” But that doesn’t feel quite right either.

There is an ethical difference between being truthful and oversharing. You don't have to share every detail in order to still be ethically truthful. It's an art in itself to maintain that brevity and poise while still being truthful.