Originally Posted by
Eloah
If I remember correctly, we are given snippets of information that some of the "greater" nations from back in the day had other races among them besides the primary one. This goes for Allag as well. The primary race were Hyurs, but I think Elezen and Miqo'te made up part of the empire as well. How they were treated is a different story.
As for Severa, I wouldn't say she's a retcon per se. More like she's another subtle piece of information given to us. Genetics are wierd, and how they choose to show up is wierd as well. For all we know Severa could be 3/4th Garlean, maybe her mother was already a half-breed. But I think she's more a clue as to how "little" the other races know about breeding.