Years ago, it had been a common belief among Ancient Near East (ANE) scholars that the Genesis Flood narrative was copied from other ANE cosmogonies. For example, the Gilgamesh Epic, which records a flood that killed everyone except for those on the boat, is older than the Mosaic account in Genesis. Is this evidence of Moses having copied the earlier record? It may not be evidence, but without something to show where Moses received his information, the critics may have a legitimate charge, at least on the face, but what lies beneath the cursory read?
The Bible shows us that Moses’ sources may have been at least as ancient as the Gilgamesh Epic. Nevertheless, we don’t know that for certain. Moses’ sources may have been copies of the autographs passed down from Adam to Noah to Abraham to Moses. The book of Genesis seems to be built up around ten genealogical records. The extent and specific content of each record is not known for certain, but there is no reason to believe that Moses did anything more than put them together into one book and edit them in order to bring them up to date, as can be seen in places like Genesis 28:19 where the different names of a single city are explained. Later, someone, perhaps Joshua, Samuel or Ezra, edited Moses’ works in places like Deuteronomy 34:6 where the record speaks of his death and burial. This is the way the compilers of the Old Testament did things.
Of course, the above is not empirical proof that Moses had records predating the Gilgamesh Epic, but it does represent a reasonable alternative to copying or using the Sumerian epic as his source, and, by the way, even if the Gilgamesh Epic predates Moses’ sources, this alone is not empirical evidence that Moses used the Gilgamesh account of the flood.
We need to remember that those among modern scholarship who cannot admit to the possibility of revelation argue from a naturalistic worldview. There is no God, so there could be no revelation. That is their argument; they cannot entertain arguments that contain revelation without discarding their own worldview. Nevertheless, they cannot empirically prove their worldview anymore than a believer could empirically prove his, so they have just as much a problem with supporting evidence as the believer has. Their argument is from silence—no supporting evidence. For example, what do modern scholars know about the ANE? In the 1950s many scholars rejected the point of view of Biblical dependence upon other ANE cosmogonies and agreed that the differences between Israel and her neighbors’ religious beliefs were so great that there was absolutely no evidence for an evolutionary explanation. Yet, later in 2001 Mark Smith, a Biblical scholar, argued in The Origins of Biblical Monotheism that the characteristics of Judaism could be fully explained on the basis of evolutionary change! What happened in those five decades? Were there new discoveries that made the 1950s understanding untenable? Actually, there hasn’t been a single new discovery in those fifty years that could explain the different understanding.
How, then, are we able to account for Smith’s argument in his book? It is a difference of emphasis. Scholarship in the 1950s argued that it was the “differences” between Judaism and its neighbors that were important. It was the differences that proved definitive in understanding the sources of the ANE cosmogonies. Smith, however, argued it was the similarities that define the ANE cosmogonies, so Judaism could, therefore, be viewed as evolving from earlier polytheism.
The problem with this way of thinking, however, is enormous. Simply because every religion worshiped its god(s) in temples is not evidence of their evolving from one another. Such similarity would be as definitive as balls in sports. Just as football, basketball, soccer or bowling didn’t evolve from baseball because all use balls, so too, Judaism didn’t evolve from any of its neighbors’ religious beliefs, simply because Israel built a temple at Jerusalem. What is definitive is that in the innermost room of that temple there was no idol, never was. Where did the Jews get that idea? How could that have evolved from any of the ANE religions? It is the repudiation that Israel’s religion held for the beliefs of its neighbors’ that argues against Moses using the Gilgamesh Epic as his source for the Genesis Flood, but more on this in another blog.
 There seems to have been ancient family records that were kept from Adam to Moses and served as a basis for the writing of the book of Genesis during Israel’s 40 years in the wilderness and prior to their coming into the Promised Land. There are 10 of them, which Moses seem to have copied and placed alongside one another. They usually begin with “These are the generations of…” (Genesis 2:4; 6:9; 10:1; 11:10; 11:27; 25:12; 25:19; 36:1; 36:9; 37:2), but Genesis 5:1 begins with this is the book of the generations of …”
 This argument is very well made by John N. Oswalt in his book, The Bible Among the Myths; pages 11-13.