In Old Testament days, the birthright was what a firstborn son would inherit from his father. It would include the responsibility of becoming the head of the family and a double portion of the inheritance left to the children. The reason for the double portion was because the firstborn would be responsible for supporting the mother. The blessing would be a pronouncement made by the father to his sons of what he envisioned for their lives. An example is found in the story of Esau and Jacob. As the firstborn, Esau was entitled to the birthright, but he sold it to his younger brother. Jacob then deceived his father and got the blessing too.