This is a huge deviation from a general pattern in Genesis. The genealogical drift of the text is always towards endogamy, or marrying within a very particular kinship structure. You may have noticed how odd it is from the get-go that Abraham marries his half-sister Sarah, who is his father Terah’s daughter by a different mother (Genesis 20:12). Isaac marries his own first cousin’s daughter Rebekah, daughter of Bethuel the Aramean, son of Nahor. Nahor himself had married his niece Milcah, daughter of his brother Haran. Jacob marries the daughters of his uncle, Laban, who is his mother Rebekah’s brother. Not only are Leah and Rachel Jacob’s first cousins through his mother (and sister-wives), but they are also his father’s father’s brother’s son’s son’s daughters. Talk about all in the family!
The exceptions to this pattern are very telling. Every time someone marries outside the kinship group, the genealogy tends to cleave off into another people that is not considered part of this burgeoning family-tribe-nation. Abraham’s relations with Hagar the Egyptian yield the Ishmaelites, often seen as the progenitors of the Northern Arabs. After Sarah's death, Abraham begets a number of sons with Keturah, whose nationality is not known, though their sons represent Eastern Arabian tribes like the Midianites.
Esau marries Canaanite women, and his progeny become the Edomites, traditional enemies of the Hebrews in the southeastern region of Palestine (Genesis 36). But his brother Jacob is explicitly told by their father to marry one of his first cousins in Aram, and later Jacob becomes Israel, the eponymous ancestor of the nation that fulfills God’s promise to Abraham that he will become the father of a mighty nation (goy gadol). When Esau learns of Isaac's instructions to Jacob, he marries Ishmael's daughter, but it doesn't seem to make a difference (Genesis 28:6-9).
While the marriage of first cousins, uncles with nieces, and brothers with half-sisters would constitute an illegal level of consanguinity in the US, there is a clear sense that outright father-daughter incest is implicitly wrong and another thing that will set you apart from the Chosen People. Lot, you will recall, is tricked into coupling with his daughters, who produce the eponymous ancestors of the Ammonites and Moabites, neighboring peoples outside the national identity of Israel.
This brings us to Judah, who marries a Canaanite woman, daughter of a certain Shua (Genesis 38:2). You will recall Judah’s sons Er and Onan are married to Tamar, and both die because God is angry with them. Tamar then cleverly engineers her impregnation by Judah, something we all find puzzling to say the least. But looking at the logic of this kinship strategy, we suddenly have to ask: to what people does Tamar belong? If she is a Canaanite, this still makes little sense, because her union with Judah would still fall outside the group, like Esau’s with his Hittite and Hivite wives. But if she is rather within the kinship group somehow, we could see that by mating directly with Judah, she is preserving the endogamous genealogy that the text seems to insist upon constantly.
|Judah and Tamar, School of Rembrandt (1650-60)|
This might appear a very desirable outcome for someone wishing to preserve the genealogical purity of the Royal House of David, which ruled in Jerusalem in later years and claimed its descent from Judah. It is not surprising, then, to find that part of the Jewish tradition makes of Tamar either a staunch member of the tribe, daughter of Shem, a priest (Genesis Rabbah 85:10) or at least a proselyte (Babylonian Talmud, Sotah 10). One apocryphal text explains her motivation by claiming “because she would not separate herself from the sons of Israel she took thought and said:‘It is better for me to die for sinning with my father-in-law than to be joined to Gentiles’ ” (Ps.-Philo, Biblical Antiquities 9.5). This interpretation suggests Judah recognizes she is more in the right than he because she has kept the purity of his lineage, while he acting on his own judgment has both married a Canaanite and consorted (seemingly) with a pagan temple prostitute. Tamar behaves outrageously for a righteous cause. Well, that certainly is one way to make sense of this story, but it is far from definite.
This brings us back to Joseph and Asenath. The exogamy of Joseph in Egypt seems to signify a real turning point in the Israelites’ standing in the world as it was then known. Jacob’s blessing formally adopts these two half-Egyptian sons as a means of completing the tribal structure of the nation of Israel as it would later be known. Now the nation is complete…and ready for the long series of catastrophes and triumphs that fill the subsequent texts of the Hebrew Bible.
There were people in antiquity who wondered about this inter-faith marriage, however. An apocryphal text known as Joseph and Asenath recounts how the Egyptian woman renounced idolatry, converted to the God of Joseph, and became a new creation through the eating of a mystical honeycomb (Joseph and Asenath, chapter 16).
We will see later this term how genealogy is important in Vergil’s Aeneid, and how you might compare its structuring function in both texts.
Further Note for Da Vinci Coders:
Genealogy is clearly an organizing principle of Genesis. There are exactly ten generations from Adam to Noah, and ten from Noah to Abraham, for example. Why ten and not seven, that all-important number from chapter 1? I’m not sure. But later genealogists clearly preferred seven. In the Gospel of Matthew, 14 (or 2 x 7) generations link Abraham to David, and 14 (2 x 7 again) stretch from King David to the Babylonian Captivity (i.e., the destruction of the Kingdom of Judah). Then another 13 stretch from the Babylonian Captivity to Jesus. So what does it mean to be approaching the last of 6 x 7 generations?