In this week's parsha, Yaakov buys the bechora rights from Eisav. This is seemingly the source for Yaakov being the ancestor of the chosen nation of Hashem. However, the bechora has to be something more than just a commodity which can be bought, inherited and sold - especially when this inheritance of rights will decide the ancestor of the Jewish nation. The parent of a nation ultimately determines the characteristics of that nation. For example, Amalek, the descendants of Eisav, were very quick to fight and kill their enemies (similar to Eisav who the Torah tells us was a hunter). On the other hand, Yaakov possessed the characteristics of an איש תם יושב אוהלים. He was engaged in Torah study and was always engaged in proper activities, while his brother only acted appropriately in his father's presence. Yaakov possessed the character traits appropriate for leading a nation, namely, kindness, calmness and respect for others, as opposed to Eisav, who cared only about himself. Even though he was the bechor, Eisav didn't deserve its privileges and therefore was denied the bechora rights. When Yaakov buys the bechora from Eisav, the appropriate father of the holy nation is in place - even though the biological bechor originally had rights to this leadership. We therefore see that even someone who is in a position of prominence won't stay there for long if he doesn't deserve it.