"Actually, Luna was born later and given away." Twilight looked each of them in the eyes, "You speak nothing of this to anypony, you got it?" Twilight waited until she had at least a nod off all of them. "Good. Celestia's father was Starswirl the Bearded. I don't know how that union really came to be, but there we are. Luna though, was conceived later, while Faust was in prison, and it wasn't willingly. Faust took Luna away as an act of mercy, but never had any intentions of letting her rule. It was Celestia that insisted they rule together, much to Platinum's annoyance I might add."