OK, but let's think about this for a minute.
A child can never give consent. We have laws stating so.
So either ear piercing is such a huge deal that only adults can be allowed to give consent, or it is such a non-deal that even children can give consent and therefore it doesn't matter the age. It can't be both. A child's consent is an illusion, and they will only make a choice within the parameters you provide, which is why there are laws to protect them.
If you think otherwise, how many children do you know choose their religion? How many have really thought about it? It's just accepted from them as truth without question or thought. They didn't choose it, no matter how much they proclaim they love whatever deity they're brought up to love. Children just don't have the mental capacity to make an informed choice. (not a religious debate, just showing a parallel).
Therefore a mother letting a 10 year old get her ears pierced is as bad as a mother piercing her baby's ears. Which really isn't bad at all. It's just a parental choice, nothing more, nothing less.
Also, it's not body mutilation, body mutilation can't be reversed. Earrings can be taken out. More importantly, mutilation is serious damage inflicted. Earrings are not. Let's stop diluting the word to evoke an emotional response.