Biblical Understanding based on the Record of Scripture
The firstborn was to receive a double portion. Israel was called the firstborn. All the firstborn in Israel were dedicated to God. In Hebrews we are called the church of the firstborn, and Jesus Christ is the firstborn of all creation.
The firstborn was to receive an extra portion. Along with this extra portion are responsibilities and duties. When these are not fulfilled, we see that the extra portion can be taken away and given to another.
