I live on my own and I don't have odd missing socks so that is true.
However, when I have a lot of clothes in the dryer and, say, 10 pairs of different black socks in there and I want a pair of socks out of it, how is it that I have to pull out 11 single black socks before I have a pair?
Angelfishsolo is possibly correct. The Hitch Hikers Guide to the Galaxy mentions the same thing happens with biros that slip quietly through wormholes in space to a biro planet. I'm sure there's an odd sock planet out there somewhere, maybe near that asteroid the Clangers live on...