In the stories of various sibling groups in the Bible, we can see that one of the clear effects of sibling rivalry is the dispersion of peoples, serving as an explanation of why different groupings of people take place. The Bible explains the development of different nations and groups of people by reference to their seminal founders, usually brothers who fought and separated for some reason. Relations between siblings in Genesis tend to be antagonistic, often based on disputes about the right of succession in the family and about the way inheritance is divided. The story of Cain and Abel, the first siblings, sets the tone for the relationship. It is not that every pair of siblings leads to a murderous act, but rather that tensions between siblings produce a variety of crimes and other problems. As with the outcome of the story of Cain and Abel, one of the results in each of these stories is the dispersion of people throughout the world as groups associated with different siblings move into new territory. Some of these peoples, such as the sons of Cain, are seen as enemies, while others are more benign. Biblical history can be seen as a history of tensions between people who are in truth related in some fashion, having originated from a common root and then having moved apart.
God gives Moses a series of laws in addition to the Ten Commandments, and one of these holds that the firstborn is entitled to a double portion of the inheritance that will be divided among the sons. If a man had sons by two wives and disliked the mother of the firstborn, it was still forbidden for him to give the right to any son but the first one. This law was violated many times, but the principle endured: "It was through the firstborn sons that family lines continued and that tradition was upheld, and in that sense the first male issue remained special in the eyes of God" (Ward, 1991, p. 137).
Interestingly, though, it is the firstborn in the ...