Genesis 38 Challenge

Genesis 38, which contains the story of Judah and Tamar, has always been troubling to Biblical scholars.  The story of Joseph begins in Genesis 37 and is more or a less a self contained story that runs all the way to the end of Genesis.  Genesis 38 interrupts the flow of the narrative and focuses on the sordid details of Judah and his daughter-in-law Tamar.  Furthermore, the story of Judah and Tamar seems to have no connection with the Joseph story.

Not only does the story of Judah and Tamar seems out of place by abruptly interrupting the Joseph story, it is also salacious.  Contrast this story with the story of Joseph who is honorable man, refusing to be seduced by Potiphar's wife.

For those unfamiliar with the story, Judah is the father of three sons.  Judah's oldest son marries Tamar and is killed by God because "he displeased God."  In the ancient world it was important that the family name be carried on. So if a husband died before his wife had a child, it was the duty of the next oldest brother to marry the widow and produce offspring in his oldest brother's name.

Judah's next oldest son, Onan, marries Tamar.  Onan neglects his duty to provide Tamar with an offspring, instead engaging in the practice of coitus interruptus (A.K.A. the pull-out method for the less delicate among you).  God strikes down Onan for his failure to do his duty.  At this point, Judah decides that Tamar is cursed and refuses to let Tamar marry his youngest son.

Tamar takes matters into her own hands by disguising herself, dressing as a prostitute, and seducing Judah at a sheep shearing festival.  The result is Judah impregnates Tamar.  Upon discovering that Tamar is pregnant, Judah wants to have Tamar burned.  However, Tamar is able prove that she was the prostitute and that the child is Judah's and Judah declares that Tamar "is more righteous than I."

It is clear that the author of Genesis did not feel he had to include every detail.  It is also clear that the author has organized the stories in Genesis in a structured way.   So your challenge is to take what we have learned so far, as well as any outside information you wish to include, and try to explain why the author includes this story in the book of Genesis?