Don Johnson

The first born in the Torah of Moses was to inherit a double portion.  The way this worked was the number of children was determined and 1 added and then each child got one share of that, except the first born got 2 shares.  For females, they got their share as part of the wedding dowry; for males when the father died.  This is part of the subtext of the prodigal, he has said in that culture that he wants his father dead.

Even the quotes Matt gives show that the rights of the first born can  be transferred to another.  And these rights were not authority over according to the Bible.