Book of Deuteronomy have given various answers to the problem. The Deuteronomistic history theory is currently the most popular (Deuteronomy was originally just the law code and covenant, written to cement the religious reforms of Josiah, and later expanded to stand as the introduction to the full history); but there is an older theory which sees Deuteronomy as belonging to Numbers, and Joshua as a sort of supplement to it. This idea still has supporters, but the mainstream understanding is that Deuteronomy, after becoming the introduction to the history, was later detached from it and included with Genesis-Exodus-Leviticus-Numbers because it already had Moses
Wife–sister narratives in the Book of Genesis are all related to each other in some way, according to Coats, sharing common content, structure and genre for communicating the content. In all three stories a promise for progeny is not a factor in the content and the structure rather the narratives have a focus on blessing. Hepner concludes, through Biblical exegesis and semantics, that it is plausible that the union of Abraham and Sarah was actually incestuous with Sarah being Abraham's half-sister. For example, in Genesis 20: 13, Abraham, talking to Abimelech, alludes to Leviticus laws or the Holiness code, by using the phrase "lovingkindness." The same word