The Bible tells the story of Esau and Jacob. Esau was born said to have been born hairy and ruddy and was a man of the field, a hunter, and a mighty and strong man of the world. Jacob, on the other hand, the Bible says was a plain (peaceful) man who dwelt in a tent.
Jewish rabbi's comment on why it says that Isaac loved Esau. The Bible says that it was because Isaac, "did eat of his venison" which is also a play on words to mean that "his game (catch) was in his mouth" suggesting a type of deception. So it seems that Isaac was already blind by Isaac's continual gifts of savory meat.
Esau came in from hunting and was famished and traded his birthright to Jacob for a bowl of lentils. The Bible says that Esau despised the birthright or responsibility to care for Isaac's family but later desired to be blessed. Esau and Jacob had very different perspectives on life. Esau focused on death, materialism, immediacy, and instant gratification while Jacob had an eternal perspective and desired to serve God and his family instead of the flesh. How can we cultivate a perspective more like Jacob?
I think that the lifelong blindness of Isaac to Esau's deception is what justifies Rachel and Jacob's little ruse. Jacob understood that the blessings of the birthright are inseparably connected to its responsibility.