Is 'backs' plural because 'their(people's)' is used?
And if 'backs' is singular, will it be incorrect?
I don't like talking about people beind their backs.
I would avoid confusion by recasting the sentence in the following way:
- I don't like talking about anyone behind their back.
Correct, but the "their" in this sense does add a bit of confusion, I think. "Their" here means "he or she"...I believe it's the modern way of saying "his" in general when refering to "anyone."