The whole point of the story of Jacob is that he understood genetics. He made a deal with his father in law so that he would get the speckled and spotted sheep and his father in law got all the rest of them. So then Jacob separated the sheep so that the speckled and spotted sheep would prosper and his father in law would end up empty handed. The shepherds had already learned how to bred the sheep even back in Jacobs day. This is known as animal husbandry, and they still use this term at the universities. The Hebrew people understood husbandry and they knew how to bred animals. This is what it means to domesticate animals. This is what the dawn of civilization was all about. Shepard dogs are smarter then hunting dogs because the Shepherds know and understood breeding better then the hunter gather people. The sheep did their mating when they came together to drink the water. So Jacob used the sticks to make pens so that he could mate the animals he wanted to mate to produce the offspring that he wanted to produce. As you know this is the difference between selective breeding and natural selection.