I've noticed a pattern where a friend will say "My DC weighs X now" or "has X number teeth" or "eats olives" or "has gone up to the next car seat now"..... etc etc and it just changes according to the stage of development.
I find myself getting irritated as either a) DS seems behind and I feel vulnerable, or b) DS is 'ahead' but I can't say because I'll look like a dick!
So I just smile and say "great" or something like that...
The culprits are usually the same handful of people (who I can't avoid) and I sometimes find myself just going quiet because I'm not sure what to say.
I'm aware that this will go on forever to the point of 'my DC has an astrophysics degree' and beyond so I'd like to know now if others are bothered by this stuff and what they do, to help me deal with these people for the next 20yrs plus!