DD actually struggles a bit with this as a part of her identity, which I gather isn't all that uncommon.
She feels a little insecure about being PG because she seems to lack an area of-- well, of singularity, for lack of a better term. She does most cognitively-based tasks and activities well, often with little practice or effort, and often at a level 2+ years beyond her agemates.
To her, it feels pretty even. To others it can seem pretty even, too-- at least if she were 16-17 and not 12-13, that is.
Just wanted to let you know that this kind of child comes with their own challenges as far as self-identity goes. It's entirely too easy for them to float by entirely unrecognized other than as "just great, really smart kids" in busy classrooms, provided that they are reasonably cooperative.