Weird story with in a story

Shortly after the Joseph narrative is introduced (37), the story is interrupted to tell another story (38). The story of Judah and Tamar has caused a lot of heads to be scratched.

To fast forward the story, Judah had three sons (Er, Onan, and Shelah) by a Canaanite woman (ouch). Er married Tamar, but was so wicked that God put him to death. To continue the line, the levirate marriage was enacted but Onan refused to reproduce with Tamar so the Lord took him as well. Judah simply wanted to rid himself of Tamar so he sent her away childless. This would have left her without any means to supply her future. Judah does promise to give Shelah when he is old enough but this is doubtful because he is afraid of losing Shelah also (38:11).
Tamar is presented as a resourceful and driven individual. She disguised herself as a prostitute and slept with Judah sometime after his wife died. Obviously, she had to be paid, so Judah promises her a kid (not human). But she wanted something as a guarantee, she requested something to identify him (signet and staff). This would have been equal to giving someone your drivers license and SS number.

This is interesting. This makes the 3rd generation to practice deceit. Jacob deceived Isaac (27:16), Judah deceived Jacob (37:31), and now Tamar deceives Judah. Even more interesting is that each of these incidents involves taking someones identity and a goat (note the scriptures listed)!

To fast forward again. Tamar has twins! The second time in Genesis that the younger twin takes precedence over the older. Perez is a predecessor to David. She is not presented as a model, but only more righteous than Judah, whose tribe would most likely have died out.

It is interesting that there are 4 women in Jesus' genealogy (Tamar, Rahab, Ruth, and Bathsheba). Isn't it ironic that all 4 are Gentiles? That all 4 had scandalous marriage situations? But this also prepares the way for Mary who would be accused of having a scandalous breach of betrothal. But the controversy of Mary was not that she had engaged in intercourse with another man not hers, but that she hadn't engaged in intercourse at all! Isn't it a wonderful testimony that God used 4 women, not of noble descent or even moral example, to fulfill his plan?