Answer to the Affirmative Action Puzzle

The father was from Oklahoma and, like many Oklahomans, was partly Indian, one eighth or one fourth as I recall.  This was enough to make him a member of his tribe, and officially an Indian, or Native American, as most say now.  These membership rules vary from tribe to tribe, and even from time to time.  Sometimes a tribe will lower the amount of tribal ancestry required, in order to enlarge the tribe for more political clout.  Sometimes they will increase it, so that the benefits going to the tribe are shared by fewer people.  In between the births of the couple's second and third sons, the tribe changed the rules to require more tribal ancestry for new members.  So, the first two sons were members of the tribe, and officially Native Americans, but the third son, with the same parents, was not.