[Spivak]

And what it thinks you want to listen to is based on what it gender it thinks you are. Gender is a strong signal about what your music tastes will be but obviously it's not absolute. If the algorithm is so pure and unbiased then why would it even want to determine your gender with this patent?

Like recommendation engines aren't magic -- they look at what people "like you" listen to where "like you" has all sorts of random demographic data as well as your personal patterns/history.