know from

[Philip Trauring]

I certainly associate the construction 'know from' as being a New
York Jewish  construction. It has certainly spread beyond New York
and beyond Jewish usage, but frequently when I hear it now, it is an
attempt to sound like a New Yorker or as a Jewish New Yorker.

I've also found the construction more common among people who
originate in Queens and Brooklyn than elsewhere.

The Oxford Guide to World English also cites it as as a Yiddish
construction (p. 198):

      They don't know from nothing ('They really don't know anything')


Philip Trauring