After all these years somebody suddenly explained to me why children must be protected from seeing nudity: it might give them sexual ideas!
Wow. Yes. If you accept as a given that seeing nudity will make anybody think sex. And if you accept as a given that sex is evil. And if you accept as a given that children are always asexual, and therefore innocent. Then it's obvious. Seeing nudity will corrupt them. (Well, I guess you also have to accept as given that an asexual being can become a sexual one by casual visual input.)
In fact it's so obvious that nobody ever explained it! And, to me at least, the idea is so alien that I never understood it! So there we stand on separate little islands, totally foreign to each other.