Well, I don't know anything your grandpa or much about your world, but I'm gonna assume that was a different time.

[Or something. Or her grandpa was an orphan. Or didn't do it alone]

Besides! I'm not saying you can't travel around the world! Just suggesting it'd be better to do it in the company of someone like the Avatar! And what's wrong with that? She's not nearly old enough to be uncool yet!