While not knowing someone's gender poses grammatical challenges in English, it has created even larger headaches as Facebook expands to other languages, where a gender-neutral option isn't available in plural form.
"People who haven't selected what sex they are frequently get defaulted to the wrong sex entirely," Naomi Gleit, a Facebook product manager, wrote Friday in a company blog.
Transgendered people and other users who find the male-female distinction too limiting will still have the option of removing gender entirely from their profiles.
This isn't the first time Facebook, one of the world's most popular social-networking sites with some 80 million users worldwide, has had to confront grammar.
At first, members were restricted in what they could say in "status updates" for their friends, as in, "Nick is wasting time on Facebook." Each update had started with the member's name and "is," followed by a blank box.
Late last year, Facebook quietly dropped the "is," allowing users to supply their own verb and write updates such as "Nick just wasted time on Facebook."