Any theories of Goku Black?

He seems to hate the saiyans, even though he looks like Goku, and he somehow knows Goku and Vegeta even though they've been dead for years in that timeline. He even knows who Beerus is. I'm thinking he's some kind of alien that hates the saiyans and took goku's form for some reason. Maybe someone similar to Bebi. It can't be Goten because Goku died before he could be born.

yeah the Goten "theories" are squashed I think at this point the best one I've heard so far is Black being a makaioshin or a demon that is inhabiting Goku's body.