Yesterday the girls and I visited my good pal K. Her two boys and my two girls are the same ages and have known each other since infancy.

K unearthed a box full of home movies from when our kids were little. It was a rainy day and we thought it might be fun to show our increasingly too-cool, eye-rolling teenagers movies of themselves at age 2 taking a bath together (it’s so satisfying to really mortify a 13-year-old).

So we’re watching these tiny, completely un-self-conscious two-year-olds toddling around in diapers and droopy overalls. So utterly clueless are they of the metamorphosis they will undergo in just one short decade. They have no idea how often they will need to stare at themselves in the mirror, or how much they will care about how their hair looks. They have no idea that allowing their parents to choose their clothes will become the most horrifying thought on earth, or that one of them will insist on wearing something called Uggs on her feet.

I wondered if our 13-year-olds–she with her pout and perpetual eyeliner, he, wearing a knit cap even though he’s inside–are really the same people as those tykes. I mean, they have the same genes as those cute, goofy toddlers, but are they the same people? Know what I mean? (Do I sound like I’ve been smoking pot? I swear I have not.)

But what blew my mind more than the toddler-to-teen transformation were the the baby girl’s parents, who wandered randomly in and out of the frame. Talk about clueless. Who are those people–that curly-blond-haired woman with the impossibly thin and graceful arms that she won’t appreciate until she sees this video 11 years later? And that lantern-jawed man in the green shirt with whom she exchanges a kiss, a touch, a hug, some kind of affectionate gesture every time the camera catches them? Who are they, that young man and woman who seem to genuinely love each other?

Yup, we all know who they are. Still, isn’t it freaky that these two have the identical genetic make-up as a pair who now never touch, avoid looking each other in the eye, and pay an exorbitant hourly fee to a woman who will legally pronounce their togetherness a thing of the past? If you had told that couple back then that they’d be divorcing in 11 years, they’d never have believed you. Nev. Er. No way.

What am I getting at here? I guess it’s that while it’s always astonishing to watch children grow and change, we expect and accept it. That a decade can turn a happy couple into a divorcing couple, though, is mysterious and sad, even though, that, too, happens all the time.