When you're someone's mother, the continual reappearance of laundry is more the issue than the periodic disappearance of socks.

(I have a large laundry basket which is devoted to single socks. Every few weeks I go through it and try to match up as many singletons as possible. The basket has yet to get less than half-full, and I know for a fact that friends' single socks have migrated to our house just to get in that basket. It's kind of obscene, really.)