User blog comment:Emily Windsnap/How old are the Merlin characters?/@comment-2405:6E00:EC2:7200:90C7:D86B:286B:B0CB-20190331101736

Morgana would likely be older then Arthur or Uther wouldnt try to hide that she was his real daughter. If he diddnt hide it she and everyone else would see she is the rightfull heir as she is older. If she was younger there would be no reason to hide except the fact that he cheated on his wife.