Have to comment on "tone deaf."

There really are people who are "monotones." My older son is one. He inherited this from his father (different father from younger son who is a musical prodigy). I sang to him from the minute he was born, and he grew up around just as much music as the other child. Loves music, but can't reproduce the sound, no matter what. I don't know if monotones hear the sound right but can't reproduce it, or hear it wrong.