It doesn't necessarily have to be a CS-y response. I mostly gave psychology background information, because it seemed to speak more to my capabilities. Be yourself in answering. If you have something different/quirky that can tie in, bring it up! If you feel more comfortable talking about it than other things, your interview will feel a bit smoother than trying to pull things out of the air. Plus, it might be a new take on the question which could pique the company's interest.