User blog comment:Morganamagic7/Siblings Age/@comment-5102537-20130220213811

It was said by either the producers or the actors/actressess that Morgana is older than Arthur. It would also match Uther's statement towards Katrina/the troll that he has never been with another woman ever since Igraine died.

The fact that Morgana wasn't "here" during the Great Purge as Uther said in the first episode means that she wasn't living in Camelot but with Gorlois, wherever that was. She came to Camelot at the age of ten years. She was also a baby or toddler during the Great Purge, so she could have never remembered anything about it, or better, anything that happened before Arthur's birth when Uther took the throne, since none of them was even born at that time and magic almost destroyed the land when Uther was young and came to Camelot.

Morgause is much older than both Arthur and Morgana. If Morgause was supposed to be around the same age, they would have chosen an actress who isn't ten years older than Katie McGrath and Bradley James.

So actually, Morgause was born years before the Great Purge. She also claimed to know Igraine which would be impossible if she was born around/during the Great Purge since Igraine died at that time. Why she was smuggled out of Camelot as a baby is one of the most annoying riddles that the showrunners never bothered to explain to us.

Morgana was born before Arthur, maybe two or three years before he was born, given that Igraine couldn't conceive, which takes some time to figure out, and Uther obviously was extremely faithful/in love with Igraine. And Arthur was indeed at least twenty years old in season one. But actually, he must have been older because Uther said in the very first season that it had been twenty years since the dragon was captured and all the others killed. He started this all after Arthur's birth and I doubt that Camleot managed to kill all the dragons, all the sorcerers they hunted down and captured Kilgharrah within just a few months. According to that, the Great Purge has lasted for only a bit less than a year and all the magic-users/sorcerers and dragons were killed in super-speed, because he didn't say that it all started twenty years ago but that it ended twenty years ago.