Thanks for all the feedback. It has been helpful to hear all of your stories and thoughts. I have decided that I have done my duty as far as sending Mom the stats and just let things be unless M or M's Mom brings it up again.

FWIW, M regularly kicks my son's butt in karate. He's a foot taller and has been doing it much longer. So yes, he has his time in the sun, I suppose.

The whole situation may be exacerbated by the fact that this boy is the firstborn in a large family, and recognized as, "the smart one". You know how those labels can bite you...

My oldest DS actually had trouble with this when DS #2 came along. He was fine with little brother having other strengths, but he really struggled when he realized that little brother was also very gifted. We'd never consciously encouraged it, but oldest DS formed his identity around being "the smartest". Part of the issue with him is that he has AS and tends to think in very black and white terms. Therefore, if DS2 was gifted, and he did some things earlier than Ds1, was Ds1 still gifted?