I love my mom and all, but I also want to recognize another set of mothers—those blobs of yeast and bacterial cultures found floating in unpasteurized cider, wine vinegar, and other fermented liquids, like cloudy constellations of pond scum. The Dutch have a word for mud and mire (modder) that may have lent its name to these mothers, but given the proliferation of the term across Europe—French mère de vinaigre or Spanish madre del vino—etymologists suspect that these slimy sediments of mother derived from the mother who takes care of you.
Two mothers seemingly at odds, right? Well, thankfully, the Oxford English Dictionary made a valiant, if somewhat perplexingly worded attempt, to tease out exactly why the lees at the bottom of the barrel came to be named for your female parent:
The transition of sense is difficult to explain; but most probably the scum or dregs of distilled waters and the like was regarded as being a portion of the ‘mother’ or original crude substance which had remained mixed with the refined product, from which in course of time it separated itself. (The term may possibly have belonged originally to the vocabulary of alchemy.) An explanation sometimes given, that ‘mother of vinegar’ was so called on account of its effect in promoting acetous fermentation, does not agree with the history of the use. It has been pointed out that ancient Greek γραῦς old woman, is used in the sense ‘scum, as of boiled milk,’ but the coincidence is probably accidental.
Wine left out in the open air will spontaneously ferment into vinegar if the right airborne microbes land on the surface (Acetobacter bacteria and Mycodermi aceti yeast); the oxidation process can also be kick-started by mixing in the cloudy undeﬁned bacterial and fungal cultures left at the bottom of an old vinegar container—an old, yet reliable, mother. These cultures work in much the same way that yeast or sourdough starters give rise to beer and bread (why these cultures are more often called starters and not mothers remains one of the many vagaries of the English language). Perhaps, then, it’s not all surprising that one mother gave birth to another.