How old was Jacob when Joseph was born?

Today, we read of the beginning of the story of Joseph in Genesis. Theologians treat Joseph as a pre-figure of Christ because he was sold by his brothers. But in the end, he saved them from severe famine. Similarly, Jesus was betrayed by Judas, abandoned by all his disciples, denied by the future Pope, forsaken by all his disciples and countrymen. But in the end, Jesus saved us all from the bondage of sins.
Scholars generally agree that the book of Genesis pieces together various traditions and folklore. The story of Joseph occupies the last part of Genesis and its richness in contents and details read like a novella.
This is the history of the family of Jacob.
Joseph, being seventeen years old, was shepherding the flock with his brothers; he was a lad with the sons of Bilhah and Zilpah, his father's wives; and Joseph brought an ill report of them to their father.
Now Israel loved Joseph more than any other of his children, because he was the son of his old age; and he made him a long robe with sleeves (Genesis 37:2-3).
Of course, we all know that Jacob and Israel was one and the same person. What intrigues me is the line "... Joseph ... was the son of his old age ...". How old was Jacob when Joseph was born?
It was a long story. It began when Jacob fled to his uncle Laban after cheating Esau of the blessing from their father Isaac. He met Rachael, the daughter of Laban and immediately fell in love with her. He promised Laban to work seven years for him in order to marry Rachael. After seven years, Lahan cheated him and gave him Leah, the elder sister of Rachael instead. Jacob promised to work for another seven years in order to marry Rachael. After spending one week with Leah, Jacob married Rachael and kept his promise to work for another seven years. How great Jacob's love was towards Rachael. He was willing to be a slave for Laban for a total of fourteen years! After this, he spent another six years to take care of the flock of Laban. He exercised his intelligence and took over most of the flock of Laban and left (Genesis 29-35). Within these twenty years, 11 sons and 1 daughter were born to Jacob. Refer to the following table.

Leah	Bilhah (Rachael's maid)	Zilpah (Leah's maid)	Rachael
Reuben
Simeon
Levi
Judah
	Dan
	Naphtali
		Gad
		Asher
Issachar
Zebulun
Dinah
			Joseph
			Benejamin

The youngest son, Benjamin, was born on the way when Jacob left Laban. No matter what, Joseph was born within Jacob's twenty-year stay with Laban. How old was Jacob when he first came to Laban? In his twenties, or thirties? Jacob died at the age of 147 in Egypt.
And Jacob lived in the land of Egypt seventeen years; so the days of Jacob, the years of his life, were a hundred and forty-seven years (Genesis 47:28).
Therefore, it is rather odd to describe Joseph as the son of Jacob of his old age. Anyway, let's continue with Joseph's story.
Joseph was gifted but naive at first. His naivety was probably the result of Jacob's love for him because of his mother Rachael. Joseph was a famous dreamer in the Bible. His naivety antagonized his brothers because he brought an ill report, albeit a candid one, of them to their father. He told them his dream and they hated him more. When Jacob sent him to see how his brothers fared with the flock, their brothers decided to kill him. Reuben, the eldest brother came to his rescue and dumped him in a dry pit.
And Reuben said to them, "Shed no blood; cast him into this pit here in the wilderness, but lay no hand upon him" -- that he might rescue him out of their hand, to restore him to his father (Genesis 37:22).
Somehow, Reuben left his brothers for a while. A caravan of Ishmaelites came along. Judah proposed to sell Joseph to the Ishmaelites who brought him down to Egypt.
Then Judah said to his brothers, "What profit is it if we slay our brother and conceal his blood?
Come, let us sell him to the Ish'maelites, and let not our hand be upon him, for he is our brother, our own flesh." And his brothers heeded him (Genesis 37:26-27).
When Reuben returned to the dry pit and saw that Joseph was missing, he rented his clothes (Genesis 37:49). In the end, Judah was included in the genealogy of Jesus, not Reuben, the son of Leah, the first born of Jacob. In ancient times, the first born usually enjoyed special privileges. Yet, most of the time, God did not elect the first-born, Cain, Ishmael, Esau and Reuben etc. God has His own logic.
Meanwhile, Joseph suffered because of his special gift. He needed to mature beyond this special talent. In the course of time, Joseph was transformed from a dreamer to a dream interpreter which did him good. As a dreamer, Joseph was hated by his brothers. As a dream interpreter, Joseph was elevated to the right hand man of Pharaoh. Students, whatever talents you have, you need to develop and polish them into a profitable and useful strength.

Dear Lord, discipline me so that I can put Your gift into profitable use for my students. Amen.