Did Esau or Jacob sin inside their mother's womb?

[tonychanyt]

Sand tiger sharks practice intrauterine cannibalism:

as the sharks develop their embryonic teeth, they start to eat the other embryos, killing their unborn brothers and sisters, as well as the unfertilized eggs. It's survival of the fittest in the womb until only one shark remains.

Sharks have no conscience before God. Sin does not apply to them.

Genesis 25:

21 Isaac prayed to the LORD for his wife, because she was barren. And the LORD granted his prayer, and Rebekah his wife conceived. 22 The children struggled together within her, and she said, “If it is thus, why is this happening to me?” So she went to inquire of the LORD. 23 And the LORD said to her,
“Two nations are in your womb, and two peoples from within you shall be divided; the one shall be stronger than the other, the older shall serve the younger.”
24 When her days to give birth were completed, behold, there were twins in her womb. 25 The first came out red, all his body like a hairy cloak, so they called his name Esau. 26 Afterward his brother came out with his hand holding Esau’s heel, so his name was called Jacob. Isaac was sixty years old when she bore them.

Did Esau or Jacob sin in that scenario?

I don't think so. Ro 9:

10b when Rebekah had conceived children by one man, our forefather Isaac, 11 though they were not yet born and had done nothing either good or bad—

Paul didn't think the babies struggling inside Rebekah's womb should be label as good or bad.

in order that God’s purpose of election might continue, not because of works but because of him who calls—

Paul discussed God's sovereign election, not the moral status of unborn children.

12 she was told, “The older will serve the younger.” 13 As it is written, “Jacob I loved, but Esau I hated.”

Paul quoted Malachi 1:

2 “I have loved you,” says the LORD. But you say, “How have you loved us?” “Is not Esau Jacob’s brother?” declares the LORD. “Yet I have loved Jacob 3but Esau I have hated. I have laid waste his hill country and left his heritage to jackals of the desert.”

Neither Esau nor Jacob sinned before or while they were being born. Esau sinned after he was born after his conscience was accountable to God. Particularly, he sold his firstborn birthright to Jacob. That was a grievous sin.