Spread among young families there is an ocean of baby clothes. When you’re expecting, you toss in a bucket and haul some out. When your child outgrows them, you try and throw them back, along with most of the new clothes you were given, like that hand-knitted jumper that junior refused to wear.
So just like any population, the amount of babyclothes in any house equals recruitment (gifts) plus immigrants (hand-me-downs), minus mortality (things thrown away), minus emigration (stuff you pass on).
What’d be most interesting would be to study the garments’ migratory patterns: Where do they go? How long do they survive? What’s the network structure?
You could investigate by setting up a labelling-and tracking system similar to Book Crossing or Where’s George?. People who had more than one child could also do mark-recapture studies, which gives me an excuse to mention my own pioneering work on the film direct Mike Leigh, something I am still rather pathetically proud of.
(Whenever I think about the ecology of everyday stuff, I think about this 1990 New Scientist article on the population biology of internal mail envelopes by Bill Sutherland.)
To desperately shoehorn in a proper science angle, this strikes me as being very slightly similar to the question of connectivity between coral reefs. One of the important topics in reef biology is understanding where the fish come from – are they born on the reef and stay there, or do they come from somewhere else? How much movement is there between reefs?
A dozen years ago, according to this paper, it was "generally assumed that larvae disperse away from their natal population so that local populations operate as 'open' systems, driven by recruitment of larvae from other sub-populations." But some studies (such as that one I just quoted, which looked at the fate of 10 million small fry on the Great Barrier Reef) find that many fish on a reef grew up there.
This varies, of course, depending on things such as how isolated a reef is, and understanding connectivity is a crucial question for reef conservation.