Where can I get mother of vinegar that wasn't derived from apple cider vinegar (nor from another apple source)? I'd rather it not be from pears, either. I do have my suspicion that regular vinegar does accumulate some acetic acid bacteria (even if you don't see it), however.
Based on my experience with vinegar and lacto-fermenting with it, I'm guessing that even regular distilled white vinegar has some acetic acid bacteria in it. I mean, when lacto-fermenting things with vinegar, the lids suck down (instead of building up pressure). My hypothesis is that acetic acid bacteria use up the oxygen (and carbon dioxide, too) and cause this to happen. I could be totally wrong.
I've never seen visible mother of vinegar develop in an old vinegar bottle, though.