FWIW, I haven't had time this morning to read any of the replies, and I apologize for that! I just wanted to throw a brief thought out there.
We don't have the same exact issue at our house because our obviously way-out-there kid is also the oldest sibling. OTOH, we do have some very large ability and achievement differences among my kids. Plus ds is one of those kids that the other kids at school seem to always label as "the brain" etc. So ds sticks out. He qualifies for programs that his sibs don't necessarily qualify for because of his IQ and achievements.
It's also rarely been an issue - every now and then something will be said but nowhere near as often as other things come up in terms of fairness, sibling squabbles etc. It's just a part of who he is, same as our youngest is so far beyond the rest of us in athletic ability. Maybe it's helped that our EG ds is also 2e so he's had his share of struggles, our youngest is also 2e and has her share of challenges, and the non-exceptional kiddo caught in between has had medical challenges - maybe that's made it easier for each of them to see that we all, as human beings, bring different talents and strengths to the table and that we all have our challenges. I'd like to think that another part of it is that my dh and I have tried our best to pass on our values in the way we live, which include believing that everyone is special and we are all in this together. Being smart is cool, but it's not the only thing in life

polarbear