Is Kan the Elder Brother or the Younger Brother?

The older brother is the one that's privileged by status, right? That also means that if there are possessions to be handed down the generations, the older brother gets them. And so right off the bat you get this dicotomy between the two rolls. Now, interestingly enough, kaine has privilege, but he's not the one that's favored by god tha. It's actually abel, who doesn't have the right that the first board has, who actually turns into the person who's the proper manifestation of the ideal....