Wow - I've definitely seen parents brag about their kid's athletic abilities- not a problem for me, even though my DS7 is not a "natural athlete" by any stretch. We live in a sports town and athleticism and sports teams seem to matter to the parents.
The only parent I've heard openly, frequently brag about her kid's IQ and musical ability actually has a kid who was playing by ear at a young age and an IQ verging on profoundly gifted- so he is truly extraordinary.
I talk with parents I know pretty well about DS, but primarily in the context of educational challenges and frustrations- I could probably tone it down.
I think six is an amazing year of early elementary school and learning- it's easy to be a bit too excited by their triumphs. I bet this same group of parents will calm down in a year or two.
I remember thinking my son showed early promise of swimming greatness- but when he started the summer swim team he was probably 3rd or 4th out of 10 boys. Good- not great. It made me more cautious in my thinking.
