I have to admit that would have made a lot of sense to me in terms of the legends and so on. It also would have been a lot cleaner to figure out because then you just have one person to invent - Morgana's mother. Despite being told Igraine was barren I admittedly haven't ruled that idea out, mainly because I'm a legend boffin and I like to keep on top of things. lol! There is more to the story than meets the eye and I'm not ruling out any possibility until the truth has been revealed on screen.
To be honest I think the cousin idea is a bit... meh. But that's just me. If Morgana and Morgause were FULL sisters I might be more willing to go with it but because they're only half it seems a bit too confusing. I mean that does seem to be the case but for it to be revealed that they're all cousins? Meh. I'm also a little concerned because you have to invent so many parents for everyone. You have to invent a mother and/or father for Morgause and a mother for Morgana. Also, which parent do they share? I used to think that maybe they shared a mother because of the bracelet, but then when I rewatched the episode I realised that Gaius seemed to make out that Morgause had a right to wear that bracelet. ("There is only one person other than Morgana who would have cause to wear such a bracelet") which strongly suggests that Gorlois might have fathered Morgause.
Either none of this goes anywhere to explain why Uther seemed so freaked out that Morgause survived. It couldn't have had anything to do with magic because she was born long before Uther turned against magic. It MUST have meant something whether Morgause lived or died, which suggests that Uther (and maybe Igraine) might be tied into Morgause's birth.
That said I think a family link between Arthur and Morgause MUST exist whether they are cousins, siblings, or some other blood relation... the fact they wanted Morgause to have that hair colour rather than the same as Morgana suggests they are doing something with the family tree,
Re: I have a theory or two or three...
To be honest I think the cousin idea is a bit... meh. But that's just me. If Morgana and Morgause were FULL sisters I might be more willing to go with it but because they're only half it seems a bit too confusing. I mean that does seem to be the case but for it to be revealed that they're all cousins? Meh. I'm also a little concerned because you have to invent so many parents for everyone. You have to invent a mother and/or father for Morgause and a mother for Morgana. Also, which parent do they share? I used to think that maybe they shared a mother because of the bracelet, but then when I rewatched the episode I realised that Gaius seemed to make out that Morgause had a right to wear that bracelet. ("There is only one person other than Morgana who would have cause to wear such a bracelet") which strongly suggests that Gorlois might have fathered Morgause.
Either none of this goes anywhere to explain why Uther seemed so freaked out that Morgause survived. It couldn't have had anything to do with magic because she was born long before Uther turned against magic. It MUST have meant something whether Morgause lived or died, which suggests that Uther (and maybe Igraine) might be tied into Morgause's birth.
That said I think a family link between Arthur and Morgause MUST exist whether they are cousins, siblings, or some other blood relation... the fact they wanted Morgause to have that hair colour rather than the same as Morgana suggests they are doing something with the family tree,