My 18 (soon to be 19 in two months) year old son, got a tattoo a couple of months ago.
He's wanted one since he was 16. I said no at that time and told him I'd prefer that he waited until he was of age. Frankly, I was hoping that in time..he'd forget about it. No such luck.

I might add, that the tattoo shop he went to
WILL NOT work on anyone under 18. The owner told him, that he doesn't care if the teen has parental permission, or if the parent accompanies their teen. His policy is strictly over 18. I respected that.
That being said...telling him he would never be able to get one..I knew would leave me in a position of having no input, if and when he did get one. Let's face it....the kid was gonna do it

so I wanted some input as to what, and where it would be located.
He has a cross on his upper arm covering his bicep. It's tasteful, and not overly ornate. I was okay with the cross, as we both agreed he wasn't likely to change his religion. It's also in an area that can be easily covered by a shirt sleeve, so as not to interfere with any restrictions from potential employers.
What can I say, he's my youngest..they wear you down with age! LOL!

Frankly there was a time when I would have been totally opposed to it. Now, not so much. There are worse things..and again, given what it is, and it's location it was something I could live with. Certainly, not a battle I chose to have.
As for middle school...I have a middle school niece and nephew...they haven't asked, nor have they mentioned anyone they know having one.
Ridiculously young for such a "forever" decision.