I think it's also telling that these claims are all about things the child can recite in response to a stimulus (letters, colors, etc.). Probably many bright youngsters can memorize such things. I think our whole culture has gotten over-obsessed about these things as signs of being advanced.
What I
don't hear from these types of parents are
idiosyncratic stories about their children's abilities. For example, Hanni (25 months) has invented a game called "pretend go duck park." I do a lot of the story-telling, but last night she contributed the idea that we needed to leave the duck park because it was too loud, so we drove away in a truck (she has never been in a truck), and Hanni drove the truck and Mama sat in the back with the koala and the sun-bear. (Oh sorry, did I just slip into the brag thread?

) Anyway, my point is, you don't find that kind of stuff on the "Kindergarten-ready" check-lists.
Until I hear
that kind of story, the kind that doesn't follow the popular script of what an advanced child does, I just smile and nod and make polite noises.