(Words in italics are words not found in the Hebrew text but need to be supplied in the target language, English. Words underlined are a Hebrew idiom. Words in brackets  are in the text but not needed in the English translation and can still be understood without them.)
Hebrew Translation: Jacob dwelled in the house of his father in the land of Canaan. These are the descendants of Jacob: Joseph, a son of 17 years, was shepherding in the flock with his brothers. He was a boy with the sons of Bilhah and with the sons of Zilpah, the wives of his father. And Joseph brought their bad report to their father. Now, Israel loved Joseph more than all his sons, for he was a son of his old age [to him]. So, he made for him a tunic of various colours. His brothers saw that their father loved him more than all his brothers, so they hated him and were not able to speak to him peacefully. Then Joseph dreamt a dream and he told his brothers, and they hated him even more.
Commentary: As we read any historical narrative like this, we must always keep in mind that the narratives told are description, not prescription. That is, historical narratives describe what is happening at this time and place; they do not prescribe what ought to be and what not ought to be. I bring this up because of Jacob’s polygamy and his favouritism toward his son, Joseph.
Atheists love to say, “Well, there was polygamy in the Bible, so your religion can’t be true since you don’t practise polygamy today!” Yes, there was polygamy, but in every case it’s a historical narrative describing what was happening, not prescribing what God required of His Old Testament people. If that’s what you get out of reading these, you’re not a very intellectual reader.
In Genesis 2:24, it is written, “Therefore, a man shall leave his father and his mother and hold fast to his wife, and they shall become one flesh.” It is a singular man with a singular woman. Nowhere in the Bible does God actually prescribe polygamy. Polygamy didn’t come until after the Fall—when sin had entered the world, corrupting everything, especially marriage (cf. Genesis 3:16). Polygamy is an aberration of marriage according to God’s original design. As a historical narrator, Moses as the author is merely describing what occurred at this time; he is not prescribing things as they should be.
Yet God, as the author of salvation, graciously turns sin into something good for His salvific purposes. Jacob sinned in having more than two wives, yet in spite of his sin God used his son, Joseph, to continue the seed of His promise (Genesis 3:15) to the incarnation of His only-begotten Son, Jesus Christ. Atheists will say this is God ignoring sin or that God doesn’t really care about sin after all. Yet as Christians, we know better. As Christians, we know this is God’s grace and mercy to spite sin by using it for His good purposes rather than immediately smiting us all, as we well deserve.
Lastly, the issue of favouritism is not as complicated as the former issue. Any parent knows showing favouritism toward a child is simply out of bounds, as grandparents know for their grandchildren as well. Showing favouritism only creates discord, as we see among Joseph and his many brothers. How could a parent love a child more than their other children? Well, because of sin. Sure, we can empathise with Jacob’s joy because Joseph was given to him from the Lord in his old age, a miracle even by today’s standards. But he still sinned in showing his son favouritism over his other sons, especially in such evocative ways like giving Joseph a tunic of various colours.
Yet even here, God spites sin to use it for His good purposes, which we see at the end of Joseph’s story all the way to the birth of our Lord and Saviour, Jesus Christ.