OK, I am unsure about a specific grammar point and cannot find any other source. So, please help! Which is correct: 1) You are a writer who has discovered that his editor has mangled the grammar in a newly published book. (Assuming that you are male, of course). Or 2) You are a writer who has discovered that your editor has mangled the grammar in a newly published book.

I can find a way around the problem, for example "You are a writer and have discovered that your editor...", but I really need to understand the structure of the above sentence.

Many thanks in advance. advanturous