The Book of Genesis speaks of the relationship between Jacob and Esau, focusing on Esau's loss of his birthright to Jacob and the conflict that had spawned between their descendant nations because of Jacob's deception of their aged and blind father, Isaac, in order to receive Esau's birthright/blessing from Isaac.
This conflict was paralleled by the affection the parents had for their favored child: "Now Isaac loved Esau, because he did eat of his venison, and Rebekah loved Jacob." (Genesis 25:28). Even since conception, their conflict was foreshadowed: "And the children struggled together within her; and she said, If it be so, why am I thus? And she went to enquire of the Lord. And the Lord said unto her, Two nations are in thy womb, and two manner of people shall be separated from thy bowels; and the one people shall be stronger than the other people; and the elder shall serve the younger." (Genesis 25:22–23)
This passage in Genesis 25:26 is as if Jacob was seemingly trying to pull Esau back into the womb so that he could be firstborn. The grasping of the heel is also a reference to deceptive behavior.
In Genesis, Esau returned to his brother, Jacob, being famished from the fields. He begged his twin brother to give him some "red pottage" (paralleling his nickname, Hebrew: אדום (`Edom, meaning "red"). Jacob offered to give Esau a bowl of stew in exchange for his birthright (the right to be recognized as firstborn) and Esau agreed.
The birthright has to do with inheritance of goods and position both. The tale is typically biblical. Esau acts impulsively. As he did not value his birthright over a bowl of lentil stew, by his actions, Esau demonstrates that he does not deserve to be the one who continues Abraham's responsibilities and rewards under God's covenant, since he does not have the steady, thoughtful qualities which are required.
Jacob shows his wiliness as well as his greater intelligence and forethought. What he does is not quite honorable, though not illegal. The birthright benefit that he gains is at least partially valid, although he is insecure enough about it to conspire later with his mother to deceive his father so as to gain the blessing for the first-born as well.