Board Thread:Lore Discussion/@comment-85.74.137.231-20130605091958/@comment-11971006-20130804000504

To the original post:

Crossbreeding is absolutely possible. And god(s) knows how many bastards were born outside of marriage in the royal family. So in theory, we can definitively conclude that it's plausible that The Last Dragonborn, which is us in Skyrim, that an orc or an elf is a result of crossbreeding from the Royal Family. My belief is that being Dragonborn capable of absorbing dragon souls is not ONLY from descending from Tiber Septim, but more from being blessed by Akatosh or some other god. If we go out from this, we can believe every dragonborn have the blood of Tiber Septim, but only a few are blessed by the gods.

Well, that would mean Tiber Septim and every other Dovahkiin is related to Miraak. And if he actually is our forefather, I believe he or Herma-Mora would have mentioned it. But still, original question is very possible.