First there was Spell Check, then Grammar Check. Now there is Gender Check!
Gender Check is a Google Doc add-on that highlights gender words in any Google Doc. 
In addition, it adds a background colour to selected paragraphs. If a paragraph contains only a single gender, then it will be coloured pink, blue or green. If there is a mixture of gender words the paragraph will be coloured yellow.
Another powerful feature of Gender Check is that it can convert text from one gender to another in a few seconds.
This add-on was designed for teachers who need to check report comments for many different students. Gender Check will quickly check for gender errors, and also enable comments to be converted to opposite genders accurately. (Teachers often want to use the same comment for more than one student.)