Jacob deceived his father Isaac, and supplanted his brother Esau. Isaac may have questioned himself, asking what he had done wrong or how he had failed that his son would do such a thing. Look at Jacob’s deception,

But Isaac said to his son, “How is it that you have found it so quickly, my son?” And he said, “Because the LORD your God brought it to me.” Isaac said to Jacob, “Please come near, that I may feel you, my son, whether you are really my son Esau or not.” So Jacob went near to Isaac his father, and he felt him and said, “The voice is Jacob’s voice, but the hands are the hands of Esau.” And he did not recognize him, because his hands were hairy like his brother Esau’s hands; so he blessed him. Then he said, “Are you really my son Esau?” He said, “I am” (Genesis 27.20–24).

I do not see anywhere in the Scriptures where the Lord blames Isaac for the failings of either one of his sons. No, each man was his own person. Isaac undoubtedly did his best as a father, but from there, his sons chose the paths they desired.