[kazinator]

Some people don't like using "they" as a singular, myself included, in serious writing.

Though the singular "they" has been in the English language since something like the 14th century, for the past hundred-and-fifty or so years, some prescriptive grammarians have been advising against it, insisting that it's an error. I is perhaps due to the efforts of these grammarians that "they" has come to be regarded as informal, giving text a colloquial or conversational flavor.

How you can avoid sexism is my sometimes using "he" and sometimes "she" as a meta-variable for some unspecified person (consistently for the same person).

If you make the he:she ratio exactly 50% in your corpus, you're above all accusation of sexism.