It has long been considered acceptable, except in the most formal writing, to use the pronoun “they” and associated forms to refer to a single person whose sex wasn’t specified or important to the story.
- Formal: Everyone should choose his or her favorite book.
- Acceptable: Everyone should choose their favorite book.
- Really old: Everyone should choose his favorite book.
By using the plural pronouns they, them, and their to refer to a singular antecedent, the writer or speaker also removes any sexism from the writing.
When I was in college, I was told to refer to singular antecedents whose sex was undetermined with masculine forms half the time and feminine forms the other half of the time. Some of my students—I never taught English, but I did require students to write papers—told me their English teachers had told them if they were a boy, they should use the feminine forms so as not to appear chauvinistic and vice versa.
But even by that time, the use of the plural third-person pronouns to refer to a singular antecedent was becoming very popular, especially in speech and then in writing. Even President Barack Obama used the plural form to refer to a singular antecedent in the 2012 State of the Union address (and I’m sure in other places):
Every business can write off the full cost of new investments that they make this year.
and
If we take these steps—if we raise expectations for every child, and give them the best possible chance at an education, from the day they are born until the last job they take—we will reach the goal that I set two years ago.
Formal usage would have required the use of “it makes” instead of “they make” and the use of “give him or her” instead of “give them.” And I’m not trying to correct the president’s grammar, because the way he said it wasn’t wrong, just a little informal, as speeches usually are. In formal writing, you had two options: (1) Change the antecedent to the plural, “all children,” so you could use “give them” and (2) change the pronoun to the singular form, “him or her,” or whichever you prefer.
The difference between the singular and plural is also disappearing in the first person (I, we) and has never really existed in the second person (you), despite what some people say about “y’all.” Sentences like, “Our business can write off the full cost of our (instead of its) new investments,” have been justified on the basis that the business refers to several people, in the plural. Grammar puritans have been much more reluctant to allow a change in the third-person forms, however.
Now that Facebook decided to allow users to enter a new kind of gender, called “custom,” by choosing from a list of 10 possibilities, most of which have indeterminate sex, the company has also decided to allow all users to specify the pronoun that’s used to refer to them in Facebook messages, the Associated Press reports.
For example, whenever you look at a timeline for someone who’s not your friend, you have seen in the past a message like, “Do you know G? Send her a friend request.” Now, under the new rules, if “G” so specifies, that message would change to, “Do you know G? Send them a friend request.”
This has the added benefit of not letting non-friends know your sex, if you want to keep that information away from strangers who may stumble upon your timeline by mistake.