User blog comment:Emily Windsnap/How old are the Merlin characters?/@comment-72.192.17.10-20140810123139/@comment-45.24.177.102-20160804060348

I tend to agree that she's older because when she found out she was Uther's daughter she believed herself the rightful heir. Which to me says firstborn. Otherwise she would't have any reason to call herself the "rightful heir" and tak about her "rightful place on the throne".