Where did the book of Genesis come from?

The book of Genesis gives no specific indication as to its origin. Up until around 200 years ago almost everyone accepted Moses as the author. Since that time many have challenged this on the basis of alleged linguistic differences, and other considerations. This whole scheme known as the Documentary Hypothesis or JEDP Theory proposes multiple unknown authors for Genesis as well as the rest of the Pentateuch.

It is important to realize that, due to more recent scholarship much of the details of this theory have been undermined and so there is a general trend away from it in scholarly circles. One presupposition, no longer tenable was that Moses could not have written the book of Genesis (along with the other 4 books) because writing was not developed. The finding of extensive libraries and literary works from before the time of Abraham disprove this theory.

Further to this, the finding of such works has led some to propose Abraham as a possible author for much of the earliest material, which Moses himself could not have known directly. Others have suggested that ABraham wrote much of Genesis and Moses was the final editor around the time of the Exodus in 1440-1400 BC.

Others have noted the use of 'toledoth phrases' to mark the end of particular subject areas thus suggesting that this material was on tablets, the phrases marking the end of each section and also of an indicator of the subject matter on each tablet.

In any case, neither of the authors suggested is impossible, with both being distinct possibilities. Most certainly, it is impossible to rule them out in any factual way.