If you need to consult your parents, do so. That's the same criteria as anyone. There is no programmatic way the list server can check someone's age - much less deal with the zillions of different laws in different places around the world. I do not know their age, sex, social security number, hair color, whatever. Some subscribers to the list may not be comfortable knowing your age, so you might not want to announce it to the population at large.
Ignorance is sometimes bliss.
No, there is no page for posting biographies and pictures of subscribers, nor is such a page really in accord with the purpose of this list as specifically an arena for discussion. Discussion is the interchange of ideas and comments, not the interchange of personal information. If, however, you wish to provide personal info, you may mention your own personal web page in your signature. You are quite welcome here, but this list is a lot more like a public forum meeting than a cocktail party. When you post, it is as if you have the microphone and are speaking to the entirity of a large audience.