Our own worst enemy?

I read a great post on Surfing Free's blog the other day. It was all about a flippant remark one of the women in her mother's group made. About losing baby weight.
It was a fantastic post and got me to thinking about this weird thing that happens to some women when they have a kid: they turn into these ultra-competitive, holier-than-thou freaks. They are the mums who do everything by the book, whose babies sit first, laugh first, are toilet-trained first.
And they make sure you know they are doing so.
They are the women who remark oh-so-casually about how easily the baby weight "just dropped off" when they started breastfeeding.
While neglecting to acknowledge that it may not be like that for most of us.
There are a couple of women of my acquaintance who are like this (and it is only the women - I've never met a dad who does the whole brag thing to this level). You'd swear their children never slapped, squealed or had tantrums, so Pollyanna-ish are their mothers.
OK, so one I know is an older mother who longed for ages for a child, so it is possible to understand that her view of her child may be clouded by this. But, I swear, the way she carries on about how "divine" her toddler's behaviour is requires me to reach for the puke bucket every time I speak to her.
Unfortunately, it also has the effect of making me feel like I am less of a mother than her.
Because I don't feed my child only organic food.
Because he sometimes watches television.
Because I haven't enrolled him in dance/swimming/French lessons.
Oh dear, I didn't realise parenting was a bloodsport.
See, we chicks have something deeply primal built into us - the competitive gene. That's the one where we constantly size ourselves up against other women, where we measure our success against the perceived success of others, where we sum someone up in a half-second up-and-down glance (don't you love those) when they walk in the room.
And, you know, it's not doing any of us any favours. Particularly when it comes to parenting.
I have developed a strategy for dealing with these hyper-competitive mothers. I don't know if it's actually achieving anything, but somehow it works for me. It goes a bit like this:
Hyper-competitive mum: "Little James eats all his vegetables. He's such a good eater."
Me: "Really. E doesn't like vegetables so I don't really push it, tinned can is about as far as we get."
And then, once you've opted out of the competition, the truth seems to come out...
HCM: "Oh well, um, it's really only been the last two weeks that Little James has eaten his vegies."
Okay, so there we have it.
I sometimes catch myself doing the "retaliation brag", where E has reached some kind of milestone before the HCM's child, but I do try to rise above it.
What do these women achieve, I wonder, by perpetuating the idea that motherhood is such a walk in the park, that their children are so well-behaved, that it's easy to juggle everything and still have a perfectly adjusted child?
Perhaps they just want us to like them.