Where do bubbe maysehs come from?

Ah, another myth shattered....

According to the NYT article on Yiddish I referred to earlier (in connection with Shrek), the origin of the phrase 'bubbe mayseh' - literally 'a grandmother's tale' but colloquially, an old wives' tale - has nothing to do with grandparents or seniors of any description:

It was, [philologist Michael Wex] revealed, based on a 16th-century chivalric story about a Christian knight named Bovo who improbably marries a princess under a chupah — a Jewish wedding canopy — and arranges a circumcision for twin sons. Over time, few Jews were familiar with Bovo, so the expression morphed into something said by a bubbe.

Sounds like a typical bubbe mayseh, but unfortunately, Philologos seems to agree...