This year in the Times' magazine's Year in Ideas, that annual issue devoted to not-quite-scientifically-sound science, Rebecca Skloot, daughter of brain-damaged and generally amazing poet Floyd Skloot, explains why so many single women of a certain age become cat ladies.

[M]ore than 60 million people in the United States are infected with a parasite that may migrate into their brains and alter their behavior in a way that — among other things — may leave them more likely to be eaten by cats. New research into this common parasite — Toxoplasma gondii — may offer clues to the phenomenon known to the unscientifically-minded as "crazy cat lady" syndrome.
Among other things, toxo makes rats like the smell of cat urine! As Skloot asks, "Might Toxo explain why some humans develop an unhealthful attraction to cats and apparently become immune to the smell of their urine? And might that explain the mystery of crazy cat ladies?" Well! "That idea doesn't seem completely crazy," [Toxo expert Robert] Sapolsky says. "But there's no data supporting it." On the other hand, there's no data dissupporting it either! In short, kill your cats! Call your mother. Kill her cats too.