Then said he to Zebah and Zalmunna, What manner of men were they whom you killed at Tabor? They answered, As you are, so were they; each one resembled the children of a king.
"The sons of my mother"  (Judges 8:19).  Uterine brothers were supposed to be closer to each other than those who were the sons of a common father by different mothers.  Jacob and Esau were glaring exceptions to that general rule.