One of the most common objections to the Genesis account of Creation concerns the reference to Cain’s wife in Genesis 4:17. Unless God supernaturally created a wife for Cain as he had for Adam, he would have had to engage in incest with one of his sisters.
First, we should note that Adam lived almost a thousand years (Genesis 5:5) and fulfilled God’s charge to “be fruitful and increase in number” (Genesis 1:28). Thus while Scripture does not tell us where Cain got his wife, the logical implication is that he married either a sister or a niece.
Furthermore, because genetic imperfections accumulated gradually over time, there was no prohibition against incest in the earliest stages of human civilization. The Levitical law against incestuous relationships was given by God hundreds of years after Cain at the time of Moses. Thus familial relationships were preserved and birth defects were prevented (Leviticus 18:6, 9).
Finally, the speculation that God may have created a wife for Cain as he had for Adam is completely ad hoc. The consistent teaching of Scripture is that “from one man God made every nation of men, that they should inhabit the whole earth; and he determined the times set for them and the exact places where they should live. God did this so that men would seek him and perhaps reach out for him and find him; though he is not far from each one of us” (Acts 17:26–27).
For further study, see Gleason Archer, Encyclopedia of Bible Difficulties (Grand Rapids: Zondervan, 1982).
“Cain lay with his wife, and she
became pregnant and gave birth to Enoch.”