Optimizing the Cards

Everyone is handed certain traits: a temper, a drive, a gentle streak, a pull toward people or toward quiet. How much of that is already fixed? Rashi says Yaakov and Esav struggled to come out of Rivka's womb at the doors of the Beis Midrash and of idol worship, as if each was already set. Yet the Rambam in Hilchos Deos says nature is fixed in one chapter and fully our choice in another. That tension also explains why Yitzchak wanted to bless Esav, and what we owe our own children.