How many members are female?

[Yrr]

Oh yes, the good ol' "singular they" debate. Traditionally, in the English language, "they" has usually been a plural pronoun, but in recent years there's been more tolerance for the use of "they" as a singular pronoun when the antecedent's gender is uncertain (or in the case of some intersex/nonbinary people who don't like such pronouns).

This is false, "singular they" has been acceptable since Shakespeare's time, it's a relatively recent trend (recent as in ~100 years) that people have been claiming it isn't, and those people are now receiving pushback.

If you found someone's wallet you'd check their ID to see who they are so you can give it back to them.
And you'd find you just used singular they three times without thinking about it.