edit on 12-9-2013 by Tylerdurden1 because: (no reason given)
In Genesis 4:17, Cain has a wife, though there is no account given of where his wife comes from. Excepting direct creation by God, as was the case for
Adam himself, the only two obvious possibilities for Cain's wife are that she was either a full sister of Cain or she was Cain's mother Eve.
In Genesis 9:20-27, Ham saw his father Noah's nakedness. The Talmud suggests that Ham may have sodomized Noah (Babylonian Talmud Sanhedrin 70a). In
more recent times, some scholars have suggested that Ham may have had intercourse with his father's wife.
Abraham's brother Nahor married his niece Milcah, the daughter of his other brother Haran.
In Genesis 19:30-38, living in an isolated area after the destruction of Sodom and Gomorrah, Lot's two daughters conspired to inebriate and seduce
their father due to the lack of available partners. Because of intoxication, Lot "perceived not" when his firstborn, and the following night his
younger daughter, lay with him. (Genesis 19:32-35) The two children born were directly Lot's sons and indirectly his grandsons, being his daughters'
sons. Likewise, their sons were also their half-brothers, having the same father.
In one of the tales of a wife confused for a sister, Abraham admitted that his wife Sarah is also his half-sister, on his father's side. However,
in the rabbinic literature, Sarah is considered Abraham's niece (the daughter of his brother, Haran).
Abraham's son Isaac married Rebekah, his first cousin once removed, the granddaughter of his father's brother Nahor and niece Milcah. Isaac and
Rebekah's firstborn son Esau married his cousin Mahalah, daughter of his father's brother Ishmael, while their second son Jacob married his
cousins Leah and Rachel, daughters of his mother's brother Laban. Marriage of cousins was not forbidden in biblical law.
In Genesis 35:22, Jacob's firstborn son Reuben committed incest by sleeping with his father's concubine Bilhah.
In Genesis 38, Judah, the fourth son of Jacob, mistook his daughter-in-law Tamar for a prostitute while she was veiled, and had sex with her.
The biblical character Amram married his paternal aunt, Jochebed, the mother of Miriam, Aaron and Moses.
In the book of 2nd Samuel, Amnon, King David's eldest son and heir to the throne, raped his half-sister Tamar; Tamar's brother, Absalom, learned of
the incident and, two years later, ordered his servants to have Amnon killed. It is noteworthy that when pleading in vain with Amnon, Tamar said,
"Now therefore, I pray thee, speak unto the king; for he will not withhold me from thee". This would imply that - in spite of the prohibition set
out elsewhere in the Bible - the marriage of siblings (at least those of different mothers, as Amnon and Tamar were) could be acceptable in the
society in which the story was written.