I don't know if anyone else noticed this, but during RoS when Palpy is explaining a few things to Anakin, he talks of the Sith. He explains about the great Sith who could avoid death itself, etc etc until he was killed by his apprentice (Palpy I'm guessing?). He also talks of how he could bring life into existence. Maybe Palpy is responsible for Anakins "virgin" conception through dark Sith powers? And therefore he keeps him around as he is effectively his son. It was always about the Skywalker family.
