Here is a snippet of a conversation that I read on the “Good Grammar Is Hot” Facebook group:
Is anyone else bothered by Facebook grammer?
I am sick of Facebook telling me that someone edited ‘their’ picture. It should, of course, be ‘his or her’. “George edited their picture” simply doesnt make any sense.
The best response:
I baked cookies for my grammer.
Teresa was discussing that in the news feed and you make an update, it will say, “Kate updated her interests. Kate changed her profile picture.”
However, if you elect not to have a gender on Facebook, it will read, “Kate updated their interests. Kate changed their profile picture.”
That is not correct. So many people say this, but none of them are right. Their is reserved for plurals only; it is not an alternative to his or her or one’s.
However, I’ll go out on a limb and say that I wouldn’t be surprised if this rule is completely destroyed a few decades down the road, and their will reign supreme.
That doesn’t mean I have to like it.