I think you just have to do what you do, stick up for it as much as you can, but expect that there will differences of opinion. You cannot change other people, but only hope they will respect you. It always astounds me that certain relatives see only the parts where your kid is different. As you mention, your kiddo plays outside with all the other kids (which goes unseen), but instead of whatever the expected norm of downtime is, he prefers to read or do math (which is noticed). You can't really do more than explain this to the relatives.
This is all fresh in my mind... We just had an icky experience over the weekend with relatives (who I previously thought "got" our kiddo and so we talked more about school and other interests with them than we normally would with anyone else). One relative told DH that she had studied the negative effects of acceleration, and we "weren't going to do that to our DS, were we?" Nevermind the fact that our DS has already skipped a grade and is accelerated another year because he's in an accelerated program... So I guess we've already "done" this to our kid. DH told her that things have changed since said relative had done her research, and most the findings are opposite of what she said.
Oh, she also told us that we should be doing more things that weren't so elitist (e.g., enrolling our kiddo in a FT HG program, along with the fact that we were considering giving up scouts this year with our rather crummy local pack since DS has other afterschool programs like DI and Lego League -- all apparently elitist). I said that if we had any problems with our son acting elitist, we might be concerned and investigate other solutions, but our kiddo has friends at all levels outside the program, and he gets along with them swimmingly, and the excellent programs he participates in after school are not limited to GT kids. Sigh.
