WHERE DID CAIN GET HIS WIFE?
The above question is a very old question. Other questions are perhaps more important, but this question is frequently asked (sometimes by scoffers) and should be discussed.
Genesis 4:16,17points out that Cain went to the land of Nod after he killed his brother. Verse 27 says, “And Cain knew his wife. . . .” Prior to this, only four humans are mentioned as being on the earth. These are Adam, Eve, Cain, and Able. So, where did Cain get his wife?
It is important to notice that Genesis does not furnish a complete chronological picture. We do not really know how much time passed between the slaying of Able by Cain and the departure of Cain to the land of Nod. Genesis 5:4 says, “And the days of Adam after he had begotten Seith were eight hundred years: and he begat sons and daughters.” So we see that Adam had other children. It would seem that Cain must have married one of his sisters. If he did not, one of his brothers would have needed to for the race to have been propagated.
Apparently, it was not an unusual occurrence for a man to marry one’s sister in these early days. We later read where Abraham married his half-sister (Gen. 20:12). This was before the Law of Moses and the practice was quite common in ancient times. The above seems to be the most likely answer.