The Old Testament does not begin with Genesis. Genesis is the Star Wars Episodes I-II-III The Phantom Menace/Attack Of The Clones/Revenge Of The Sith to Exodus’ Star Wars.
The Old Testament, in particular the Torah, or the Pentateuch, or the Five Books of Moses, start with Moses hizzownsef.
We’re all overly familiar with the story but I’ll boil it down:
- Egyptians hold Hebrews as slaves.
- Egyptians try to keep Hebrew numbers down by ordering genocide of newborn Hebrew males.
- Moses’ biological mother puts him in a basket, launches him down the Nile in the hopes God will look after him.
- God does; Pharaoh’s daughter snags the basket, raises Moses in the Egyptian court.
- Moses grows up, loses his temper, kills a slave overseer, high tails it for the desert.
- Moses meets Jethro, his future father-in-law, a priest of Midian, and a distant kinsman.
- Moses learns a thing or two about Semitic theology from Jethro over the next 40 years.
- Moses encounters God in the burning bush, gets his marching orders, and goes back to Egypt to free his Hebrew brethren.
The written account begins with the life story of Moses. While the Torah is attributed to him, they are books “of” his in a very loose, encompassing sense. He certainly didn’t write everything in them (there’s a couple of chapters in Deuteronomy that occur after he died); he may have commissioned the work and/or edited it.
Certainly Exodus/Leviticus/Numbers/Deuteronomy are books “of” his insofar as they are about him.
Which leaves Genesis, the “prequel” to his story that sets the stage. Personally, I think this is the work that has the most direct input from Moses, perhaps even all of it.
While raised in the Egyptian court, Moses did have contact with other Hebrews, notably his own biological mother (who was hired to nurse him without Pharaoh’s daughter being aware of their kinship). We don’t know exactly how well received he was in the Egyptian court, but he certainly felt an affinity with the Hebrew slaves.
How much of Genesis did he learn in Egypt and how much while herding sheep for Jethro?
We don't know.
We can draw some inferences.
Prior to Abraham, events and time lines are not entirely clear in Genesis. After Abraham (first patriarch of the Israelites as well as the Jewish, Christian, and Islamic faiths) things become a lot more orderly and easy to track.
By the time we get from Abraham to Isaac to Jacob/Israel to Joseph (last stop before Exodus), we have a fairly cohesive family saga.
But before Abraham, well, there things get hazy.
From Abraham onwards, the people who were to become the Israelites and Jews of the latter Old Testament and the New Testament were taking great pains to keep track of family connections and history.
To put it bluntly, there was a lot involved here: The entire future of their tribe/s and nation. Who inherited what was very crucial to know.
But before Abraham, such connections weren’t all that important. The stories and family ties become blurry, unsure. Tradition holds the various “begats” refer to biological offspring, but truth be told it may mean simply that one figure preceded or inspired another.
So essentially Genesis is some vague accounts followed by some clearer accounts leading up to well documented accounts in Exodus, etc.
Vague, BTW, does not mean “untrue,” “mythical,” or “false.” It simply means…vague.
 I have become so soured with what Lucas’ has done to his original idea that I now refuse to watch any films in the series other than the original (i.e., real) Star Wars without the extraneous sub-title. Or the wholly unnecessary CGI inserts. And Han shoots first.
 So much so that too often what we think is in the Torah isn’t there at all but is just folk tradition and/or pop culture we’ve overlaid on it.
 Clearly he didn’t think his standing with Pharaoh’s daughter would help him beat a murder rap.
 Not all Semites are Hebrews, not all Hebrews are Israelites, not all Israelites are Jews.