It's an idiotic expectation because you can't prove that somebody out there hasn't done what you have. It should be assumed until proven otherwise.

I'm not a lawyer, but my personal rule(s) of thumb are: - Could you create this work by accident? (clearly no) - Could it be mistaken for another work? (hers not that I know of, his clearly)

She is right that these expectations effectively mean most portraits are not original and anyone can copy them.