The ancestor of all Israelite people is said to be Abraham. Originally his name was Abram, meaning high father. According to Genesis 17, God unilaterally decided to alter Abram's name to Abraham, meaning father of all nations!
Anyway, one day Abraham left his hometown to settle in present-day Turkey. Later he decided to move back to Palestine to build an altar, of course, at the insistence of God. On the other hand, Abraham was sexually very active and, consequently, produced several sons: one, Ishmael, the leader of all Arabs, particularly, Palestinians, and the other one, his favorite, Isaac, the king of all Israelis.
Then we are told that one day Abraham decided to slaughter one of his sons, Ishmael or Isaac on the altar to appease the Almighty God, but God graciously commanded Abraham not to do so, but rather kill a big fat sheep instead. Thus Ishmael, according to Moslems, or Isaac, according to Jews and Christians, was miraculously saved, but enmity of Cain vs. Abel or rather Ishmael vs. Isaac has continued ever since.
Irrespective of the divinity of the case, we can undoubtedly reach a safe conclusion that the feud between families is usually of worldly kind i.e. property and estate inheritance. Definitely, Abraham had a big house with several chambers. When Abraham was alive, he could partly manage the dispute between his numerous wives, including Hagar and Sarah. However, after his death the inheritance dispute as usual erupted, just like today. The main problem of Abraham's offspring was easement or right of way. At their time, probably, they agreed for Hagar and her children to use separate exit doors.
However, as the number of cousins grew, the extent of the differences inflated, too. Now, it has encompassed the whole region, a problem that could have been resolved at the very beginning by Abraham.
Another, side of the story, relates to the absurdity of life. Writers and philosophers like Albert Camus, Sartre, Kierkegaard, Nietzsche, etc, existentialists, discussed essence and existence. Well, if man is still in state of evolution, without a master plan, then he is blameless.
Notwithstanding, we know man's problem in life is his awareness of life's absurdity. He has always tried in vain to give substance to life, among which stands his desire for a perpetual life. Politicians, corporate managers, etc, stubborn advocates of immortality dream, have been trying hard to perpetuate their lives via making a name and thus virtually remaining in men's imagination, lasting less than generation, as a placebo for everlasting life.
Again, we have closed our eyes on the teachings of Nature: Crows once a year worry about nests, copulation, raising babies and, in brief, reproduction. The rest of their lives goes on unaware of steady approach of death. The flocks of sheep during their last walk toward the slaughter house enjoy the most of their lives. Can man do that? No!