Bible, English, King James, Documentary Hypothesis, Priestly source, Holiness Code, Sexual Prohibitions
According to the documentary hypothesis, the torah was redacted together from a number of earlier source texts. The largest of these is referred to as the "Priestly source", due to its concentration on details which would be of interest to the Aaronid priesthood. Part of the law code within that source, known as the "Holiness Code" is believed to have been originally a separate document.
The Holiness Code contains several disparate laws, however, it also contains a clear group of laws relating to sexual prohibitions, at Leviticus 18, and repeated at Leviticus 22. These lists are both believed to have been based on a once separate collection, with Leviticus 18 being the historically earlier copy. There follows a paraphrased version of that list.
Sexual Prohibitions 
After the doings of the land of Egypt, wherein ye dwelt, shall ye not do: and after the doings of the land of Canaan, shall ye not do: neither shall ye walk in their ordinances. None of you shall approach to any that is near of kin to him, to uncover their nakedness:
- Mother / Step-mother
- Sister / Step-sister / Sister-in-law
- A neighbour's wife
- A woman and her daughter
- A woman not put apart from her uncleanness
- Passing thy seed through the fire to Molech
- With a beast
Defile not ye yourselves in any of these things: neither any of your own nation, nor any stranger that sojourneth among you: (For all these abominations have the men of the land done, which were before you, and the land is defiled;) That the land spue not you out also, when ye defile it, as it spued out the nations that were before you. For whosoever shall commit any of these abominations, even the souls that commit them shall be cut off from among their people. Therefore shall ye keep this ordinance, that ye commit not any one of these abominable customs, which were committed before you.