We figured out cloning a while ago, and even succeeded in cloning a few animals. When we went to the middle east Hillary Clinton (per wiki leaks) was looking for the buried nephilim and gilgamesh. The theory is that human clones do not have souls, and that they are going to use nephilim DNA from the middle east to make "human hybrids" that demons will inhabit permanently.
Removes the need to fight for possession, and gives them a physical advantage.