In Genesis 4 after Cain has killed Abel, God comes to him and curses him with a mark. Immediately following this in scripture it says “Cain lay with his wife.” Where did Cain's wife come from and also the other people? Cain tells God that he is worried about being killed. I thought only Adam, Eve, Cain, and Abel were alive then.
The events surrounding the death of Abel by his brother Cain can be found in Genesis 4:1-15. This question is directed at the events after Abel’s death, after God protected Cain with a sign. We do not know what the sign was but it must have been significant. After Cain received the sign, the scriptures say Cain had sexual relations with his wife.
So the LORD said to him, “Therefore whoever kills Cain, vengeance will be taken on him sevenfold.” And the LORD appointed a sign for Cain, lest anyone finding him should slay him. Then Cain went out from the presence of the LORD, and settled in the land of Nod, east of Eden. And Cain had relations with his wife and she conceived, and gave birth to Enoch; and he built a city, and called the name of the city Enoch, after the name of his son. (NASB) Genesis 4:15-17
So the question is, “Where did Cain’s wife come from since scripture does not mention any other children of Adam and Eve?” The answer is found in three facts: 1) Scripture does not record the name of all of Adam and Eve’s children. 2) There can be long periods of time elapse between the children mentioned in scripture. 3) Cain married his sister.
Not Every Birth Mentioned. Scripture does not always mention every child that is born to a husband and wife. Genesis 5:1-4 is a great example of this.
This is the book of the generations of Adam. In the day when God created man, He made him in the likeness of God. He created them male and female, and He blessed them and named them Man in the day when they were created. When Adam had lived one hundred and thirty years, he became the father of a son in his own likeness, according to his image, and named him Seth. Then the days of Adam after he became the father of Seth were eight hundred years, and he had other sons and daughters. (NASB) Genesis 5:1-4
This is Adam’s genealogy. Notice that the only son mentioned is Seth. Seth was born after Abel and Cain in Genesis 4:25. Abel and Cain are not even mentioned and the added comment, ” . . . he had other sons and daughters” tells us that Adam had daughters. Scripture rarely ever mentions the daughters who were born. In fact, Seth was born when Adam was 130 years of age. That is enough time for many other children to have been born.
Long Life. If we assume that Adam and Eve gave birth to other sons and daughters (one per year starting at 20 years of age), who had sons and daughters and so on, there could have been at least ten thousand people by the time Adam was 130 years old.
In order to populate the earth, brothers and sisters had to marry each other. With a population in the thousands, marriages within the immediate family were not necessary. Further, the genetic problems associated with marriages within a family would take some time to develop. It was not until much later that God prohibited this type of marriage.
Reference Links:How many kids did Adam and Eve have?
How was the world populated?