“Who was Seth’s wife?” is another way the question is sometimes asked. Cain, Abel, and Seth are the three named children of Adam and Eve in Genesis chapter 4.[i] The question seems to trouble skeptics, liberals, and other unbelievers of the Bible. Or, put another way, skeptics use the question of Cain’s wife to try to discredit the historical record of the Bible. Perhaps some Bible-believers find it troubling. Perhaps others just ignore it. In the now-famous Scopes Trial in Dayton, Tennessee in July of 1925, agnostic lawyer Clarence Darrow asked William Jennings Bryan, “Did you ever discover where Cain got his wife?” Bryan replied, “No, sir; I leave the agnostics to hunt for her.”
In some respects, Bryan’s answer is sufficient. The Bible does not see fit to go into detail about it. On the other hand, Bryan’s answer is insufficient – it may be seen as Christians avoiding the issue because they are unable to defend the teachings of Scripture. The answer comes from simple deduction of the teachings of Scripture.
The Bible does not specifically address who were the wives of either Cain or Seth. Those of us who accept the Genesis creation account as an accurate historical record find the only possible answers are that Cain (or Seth, as well) married his sister, niece, great-niece, etc.. While the latter are possibilities, the former (his sister) is most likely.[ii] This fact cannot be avoided in the sense that at least one pair of male and female children of Adam and Eve married and produced children (else there would be no nieces, great-nieces, etc. for any male child to marry).
God created two people by whom he populated the entire world. “These are the generations of the heavens and of the earth when they were created…And the Lord God formed man of the dust of the ground, and breathed into his nostrils the breath of life; and man became a living soul…and the rib, which the Lord God had taken from man, made he a woman, and brought her unto the man” (Genesis 2:4-22; cf. also 1 Corinthians 15:45). “Eve…was the mother of all living” (Genesis 3:20). God made of one blood all men who dwell on the earth (Acts 17:26). All descend from Adam and Eve and all are related.
All are sinners in Adam, and all die (1 Corinthians 15:22). The fall, “original” sin, depravity, death, are all rooted in the biblical narrative of God’s creation of one man and one woman (Romans 5:12; Romans 5:17-18). In the fall of the “first Adam” we sin and we die. In the triumph of the “last Adam” (1 Corinthians 15:45) we are made alive. Jesus Christ the eternal Word came into Adam’s race (John 1:1-14) to bear the sin of Adam’s race (2 Corinthians 5:21; Hebrews 2:9–10; Hebrews 10:12; 1 Peter 3:18) in his death on the cross (Philippians 2:8). (Without understanding the fall of man in Genesis, there is no way to understand why Jesus had to do what He did.)
Finally, the inconvenient truth of the marriages of Cain and Seth disturb some because of what they consider incest.[iii] This is an anachronism, reading back into the record as unlawful something that was not unlawful at the time it occurred. Moses gave the law restricting close intermarriage (Leviticus 18:6, 9-11). Moses’s law came some 2500 years after the time of Cain and Seth. Even Abraham, whose calling came about 430 before Moses’s exodus from Egypt (Genesis 15:13), married his half-sister. “[Sarah] is my sister; she is the daughter of my father, but not the daughter of my mother; and she became my wife” (Genesis 20:12). This would have been illegal under the Law of Moses – “The nakedness of thy sister, the daughter of thy father, or daughter of thy mother…thou shalt not uncover” – but God called Abraham as the father of the faithful! See Galatians 3:9 and Galatians 3:29.
[iii] As another argument why close intermarriage was originally allowed, some teachers point out the relative “purity” of the genetic code in the early days after creation and the now “polluted” genetic code after generations and generations of defects multiplied. This is probably true, but I am not aware that the Bible speaks to this.