See D2287 for some discussion.

Currently, Settings > Account asks you to specify "Sex". This is not shown on user profiles, and used only to choose pronouns (e.g., "alincoln updated his profile." vs "mlincoln updated her profile."). Although we barely ever (maybe never?) use it in the current English text, it's more important in some other languages.

Since "Sex" is a charged label and there is no technical or product need to conflate pronoun selection with sex or gender identity, we should focus the prompt text on pronoun selection. For example:

Choose the pronoun you prefer:

Pronoun: [<username> updated their profile. V]
         [<username> updated her profile.    ]
         [<username> updated his profile.    ]

This can be functionally identical to the current control.