Isaac and Esau were no such thing. It was JACOB (aka Israel) & Esau who were brothers, twins to be exact. Isaac was their father.
Ishmael & Isaac were half-brothers.
Try again.
I had always thought Ishamel and Issac were half brothers Abraham the father of both males Ishmael was the son of the Egyptian handmaiden Issac's mother Sara, isn't that why in Judiasm being Jewish is recognized by the mother's heritage rather than the father?