Quick question

I'm fairly new to the game, I just met Glendan from the council, so no spoilers please. I'm in love with this game and I think it's fantastic. But something has been bothering me about the natives. Some of them like Siora and Glendan have these branches or antlers coming out of their heads and no one really acknowledges it. Is there a reason for that? Is it just character design? Did I miss something or will it be explained further along in the story?