My 14 and 15 year old daughters have each been members since they were 13. There is so much of value here, so many points of view, so many cultures to expose them to. Sure, there are things that aren’t entirely appropriate for them… but they live in the world. I’m sure they’ve seen/read/heard things in high school at least as bad as they’ll see here. Mainly, I don’t have a problem with it because I’m on. We’re very open with each other, and if something comes up we just have an honest discussion about it.
That said, they are forbidden to visit the chatroom. Too much porn! Also, I do have an alternate account that I use to discuss things I’d rather they not know came from me.
*Edit: Also, it depends on the child. My oldest was plenty ready for this site the day she turned 13 (I swear she was born 30 years old). The next in line had to wait about 6 months after her 13th birthday to sign up. We’ll see if my youngest (currently 12) is ready (and interested) when her birthday rolls around in December.