Several years ago, I tutored this kid- I think he was about 11 when we started. His mom lived across the street to me, and when he learned that I played dnd he practically begged me to let him play. "Ask your mom," I said, and she said it was ok; so I reluctantly agreed and we set up a time to teach him the basics.
Come the time, he shows up with his twin brother and best friend...
The twins have long since moved away, but the best friend still plays with us today. All three were vastly entertaining, even though two were whiners and the third was a would-be thug. All my players loved them- and all the rest of them were college aged or older. In short, it was a blast. Some of the best tales of my campaign involve them- ahh, the memories!
But I must admit that those games certainly had an... ahem...
immature bent to them.
Then again, our games still do...
As to watching your language- hey, I don't want to be corrupting the youth or anything, but COME ON, people, kids starting around age 11 cuss more than anyone this side of a sailor. At least, I did, and so did all the other kids I knew at that age.... Not arguing against treating the youth tenderly, just saying, let's be realistic too. Kids are just learning to get really crude and offensive and they generally like to stretch their wings, so to speak, so in a couple of years I'd kind of expect it from the one you're considering adopting into your group.
I would say that your gaming habits might need to change if you drink a lot or do drugs at the table, though.
Ours did.
Preston, Zach, wherever you are- I raise my cup o' dice to you! Game on, my friends! (And yeah, Matt's still getting himself killed and thrown in jail and stuff all the time.)