I would argue tats, piercings, multicolored hair, etc. can be seen as expressions of one's self. And yes, I have one piercing and several smaller tattoos, which I love. Sometimes in teenagers all of the above can be seen as just plain rebellion, and they will grow out of it. I had more piercings but grew out of them, no biggie.
I do think if you wish to take your own life you should be allowed to w/out being committed...I don't like the idea of being forced against my will to conform to society's norm of "wanting to live and be happy" if I were in too much pain emotionally or physically.
I do not agree a mother should be allowed to do whatever she wishes to with her body with an unborn baby inside of her (assuming she plans on carrying it to term). In that case, her choices are affecting another life as well and may very well be causing unrepairable damage. But I still see it all the time, pregnant women drinking and or smoking...it's not like it's been made illegal. A certain responsibility is left up to the individual to take care of the life growing inside them.
That's why I think you should have to take parenting classes and have a "license" before having a child. Oh, and get a dog first, please, to see if you are even ready for the responsibility of pet ownership, let alone a child. And you should have to get a license to own a pet before you do that as well.

Basically I don't trust people to take care of anyone else, not even themselves. But I do think they have the fundamental right to decide what they want to do with their bodies.
I have no idea if I went off topic or not...sorry if I did, just kinda rolled with it.
Great topic though, thanks.