Tell me where Cain's wife came from?
Before going to scripture, let's reason on why incest is medically unhealthy. The closer the relative, the more likely any resultant children will have birth defects. And yet, if we take the genealogy of mankind literal, there was a significant increase in the overall lifespan as we get closer to Adam, especially when we get past Noah. It seems as if Shem, Noah's second son, lived for 502 years after the Deluge. He died 13 years after Sarah did, and may have also been the one known as Melchizedek, though that is by no means certain. Abraham himself is recorded to have lived for 175 years, and his father Terah, of the 8th generation from Shem, lived 205 years. As you may be aware, Sarah was Abraham's half-sister as well as his wife, having the same father in common. (Ge 20:12) Incest became strictly forbidden at the institution of the Law Covenant. Why did God finally make this illegal? Likely because the genetics of mankind had finally broken down to the point where Moses, could pray.
The span of our life is 70 years,
Or 80 if one is especially strong. (or "because of special mightiness.")
But they are filled with trouble and sorrow;
They quickly pass by, and away we fly.
- Psalm 90:10
One could reason that at this point it became too dangerous for the offspring if this practice was to continue. The DNA of humans was becoming too greatly removed from perfection.
And yet we know marriage was sacred in God's eyes. Even before the Law Covenant, Joseph knew it was a sin against God if he was to sleep with his master's wife. And likely he knew that God nearly killed a couple kings because they were about to take Sarah as wife when they did not realize that she was already Abraham's. So it would be totally wrong to say Cain had relations with his own mother, Eve was not Cain's wife, but Adam's. So, where did Cain get his wife? (Ge 4:17)
"After this Adam named his wife Eve, (meaning, "LIving One.") because she was to become the mother of everyone living." - Gen 3:20
"Adam lived for 130 years and then became father to a son in his likeness, in his image, and he named him Seth. (Adam's 3rd son (Ge 4:25)) After becoming father to Seth, Adam lived for 800 years. And he became father to sons and daughters. So all the days of Adam's life amounted to 930 years, and then he died." - Ge 5:3-5
From these 2 scriptures we can understand that Cain's wife had to be a sister, or perhaps a niece.
