Scar and Mufasa.. half brothers?

Scar and Mufasa's appearances seem to suggest that they weren't sired by the same parent. It's a quite popular theory that Scar's father was a rogue who looked like him. Perhaps Uru cheated on Ahadi?
I'm fond of the rare theory that Uru had Scar or 'Taka' with Zira's father. Making Scar and Zira biologically related but were shunned by their parents and labeled as a mistake?
