In the past, when we wrote about an unidentified individual, we would say: “Each employee who wants to enroll his/her family in benefits can check this box.”
Some people didn’t like his/her. They wanted her/his or his or her…or they fussed with tedious editing to avoid the situation. But now, “they” CAN BE SINGULAR! For example: “Each employee who wants to enroll their family…”

This usage is considered:
· Acceptable grammar. According to Merriam-Webster (definition 3), we can use “they” as the pronoun for an individual. Define_they
· Inclusive language. In fact, many nonbinary individuals prefer the use of they, them, their.

Read more about the acceptance of this practice by the Associated Press Stylebook and the Chicago Manual of Style, in Columbia Journalism Review.