The good word, in this case, is the singular neutral gender pronoun they, and Scott has a wonderful YouTube video and accompanying post on the subject.
He’s got a whole bunch of other posts about linguistics up on YouTube, and they’re all worth watching and reading. It’s nice to see entertaining pedagogy taking place outside a formal context; knowledge is a good thing, and deserves a chance to go out in public and meet people, instead of staying cooped up in the classroom all the time.
Dr. Doyle's Blog 