Personally I don't agree with very young children having their ears pierced, nor do I necessarily agree they need to reach the full age of consent to do so. Definitely it should be done at the child's request and not the parent's desire, after careful consideration and not on a whim.

There's also a world of difference between a small hole that will usually close over if left unused and irreversibly cutting a chunk of a child's genitals off, while these two things both raise questions of informed consent they should not be seen as equivalent.