The WTS does say that God explained the genetics to Jacob.
*** it-1 p. 1244 Jacob ***
Results? The offspring abnormally marked or colored, and therefore Jacob’s wages, proved to be more numerous than those of normal solid color, which were to be Laban’s. Since the desired results were obtained, Jacob probably thought his stratagem with the striped sticks was responsible. In this he no doubt shared the same misconception commonly held by many people, namely, that such things can have an effect on the offspring. However, in a dream his Creator instructed him otherwise.
In his dream Jacob learned that certain principles of genetics, and not the sticks, were responsible for his success. Whereas Jacob was tending only solid-colored animals, yet the vision revealed that the male goats were striped, speckled, and spotty. How could this be? Apparently they were hybrids even though of uniform color, the result of crossbreeding in Laban’s flock before Jacob began being paid. So certain of these animals carried in their reproductive cells the hereditary factors for spotting and speckling future generations, according to the laws of heredity discovered by Gregor Mendel in the last century.—Ge 31:10-12.
....Does Genesis 31:10-12 say that?
(Genesis 31:9-12) 9 So God kept taking the herd of YOUR father away and giving it to me. 10 At last it came about at the time when the flock got in heat that I raised my eyes and saw a sight in a dream and here the he-goats springing upon the flock were striped, speckled and spotty. 11 Then the angel of the [true] God said to me in the dream, ‘Jacob!’ to which I said, ‘Here I am.’ 12 And he continued, ‘Raise your eyes, please, and see all the he-goats springing upon the flock are striped, speckled and spotty, for I have seen all that La′ban is doing to you.
*** w50 11/1 p. 432 Questions From Readers ***
Jehovah God here gave Jacob instruction in the modern science of genetics. There were no spotted goats in the flock Jacob tended, yet the vision disclosed spotted goats. How could this be? It is apparent that the spots were not visible, yet their presence in these solid-colored animals was supernaturally revealed to Jacob and doubly impressed upon him by what he saw in the dream and by the angel’s specifically calling his attention to them. Apparently these plain-colored goats were hybrids, that is, they were the result of a cross between the spotted goats and plain goats that ran together in Laban’s flocks. Though these hybrids were uniformly colored themselves, they carried in their germ cells the hereditary factors for spotting and speckling, and, in accord with the laws of heredity discovered by Gregor Mendel in the nineteenth century and clarified and enlarged in this twentieth century, many of the offspring of these solid-colored hybrid goats were spotted and speckled. By the vision God opened Jacob’s eyes to the naturally invisible presence of the hereditary factors for spotting and speckling that were in the plain-colored hybrid goats, and Jehovah could well cause the proportion of spotted offspring to run heavy. Both Laban and Jacob acknowledged Jehovah’s interest in this matter. (Gen. 30:27-30; 31:5, 7, 9, 16) As for the point raised by Genesis 30:41, 42 that the stronger offspring were Jacob’s, it should be remembered that all the speckled and spotted would come from the hybrids, and it is a modern biological truth that hybrids are stronger than uncrossed breeds. Not all the goats in the flock Jacob tended were hybrids, and these feebler ones, without the hybrid vigor, would breed true and produce only solid-colored offspring, and which feebler kids would be Laban’s.