Genesis 4:17 mentions Cain’s wife without naming her or saying where she came from. The familiar answers are reconstructions, not information the passage supplies directly.
On a reading in which Adam and Eve are the sole original human couple, she must belong to their family. Genesis 3:20 calls Eve the mother of all living, and Genesis 5:4 says Adam had other sons and daughters. A sister or another close relative is therefore a reasonable inference within that reading, although Genesis never identifies the relationship.
That raises an ethical comparison with Leviticus 18:9 and 20:17, which prohibit intercourse with a sister or half-sister. A chronological harmonization says those laws had not yet been given. That explains how a traditional reading distinguishes periods; it does not supply biological evidence that close-relative reproduction once carried no genetic risk. Genesis makes no such scientific claim. Other family stories also preserve unions later prohibited, including Abraham’s description of Sarah as his half-sister (Genesis 20:12).
Genesis 4 itself raises the population question. Cain fears that someone will kill him, settles in Nod, and is associated with building a city (4:14–17). The text does not say he met his wife in Nod. Defenders of the single-couple reading understand the unnamed people as later descendants and allow an unspecified interval. Readers who see a wider population regard these details as signs that the story was not designed as a complete account of human population origins.
The relationship between Genesis 1 and 2 also matters. Some read chapter 2 as a close-up within chapter 1; others see distinct creation accounts arranged together, or an archetypal account of human existence. Those approaches explain the narrative’s gaps differently. None turns an unnamed wife into a securely identified person.
Romans 5:12–19 and 1 Corinthians 15:21–22 later give Adam a role in Paul’s account of sin and resurrection through Jesus. Christian interpreters may use that account to constrain their reading of Genesis. Jewish readers and historical interpreters need not accept Paul’s theological use as an explanation of what Genesis originally meant. Even for Christians, representative headship and genetic ancestry are distinguishable questions.
Later Jewish literature, including Jubilees 4:9, supplies a sister’s name, Awan. That is evidence of how an ancient reader filled the gap, not a name found in Genesis. The text leaves Cain’s wife unidentified; any fuller answer should state the assumptions on which it depends.
Read in context: Genesis 4–5; Genesis 20; Leviticus 18; Romans 5.