User blog comment:Merlin919/Is Morgause, Vivienne and Gorlois's daughter/@comment-5102537-20120815202410

You are right, it needs to be changed. It's still unknown who Morgause's father was. If she is Morgana's half-sister even though Uther is Morgana's father, Gorlois can't be the father of Morgause (otherwise Gaius as well as Morgause and Morgana would have thought that they were full sisters before they learnt about Uther being Morgana's real father).