What does the special clothing of the eldest son mean in the Middle East?

Les explains that this is still the custom in the Middle East: the eldest son is given clothes that pertain to his position, and even if people have become westernized or wear double-breasted suits, the eldest son will still wear clothing that designates him as the eldest son. Back in antiquity, it was as Jacob did for Joseph—probably a coat of many colors—and that was why the brothers became so jealous, because they saw their father designating Joseph as the head of the brethren even though he was not the eldest. Rebekah then took Esau's special designated cloak, which showed he was the eldest, and put it on Jacob, the youngest. Though this was done in the energy of the flesh, God did not stop it because He had mandated in the beginning that this is the way it should be; they were merely fulfilling what God had mandated, but doing it in the energy of the flesh while God brought it about in His own sovereign way.