This is one of the most common questions we receive. If Adam was the first man, directly created by God, and Eve the first woman, also a direct creation, and only three sons are mentioned—Cain, Abel and Seth—it is but natural that many ask: “Where then, did Cain get his wife?”
First, let’s examine whether Cain had a wife. The biblical answer is: Yes! In Genesis 4:17 we read: “And Cain knew his wife; and she conceived, and bare Enoch ….” So we know for sure that Cain had a wife and a son.
We could also ask where did Seth get a wife? Seth is a direct ancestor of Noah, Abraham, David and Christ. So Seth, as well as Cain, must have had a wife.
The answer is found in the genealogy of Adam, recorded in Genesis 5. “And the days of Adam after he had begotten Seth were eight hundred years: and he begat sons and daughters: And all the days that Adam lived were nine hundred and thirty years: and he died” (verses 4-5).
There is the answer. Adam begat sons and daughters. God had blessed Adam and Eve and said unto them: “Be fruitful, and multiply, and replenish the earth …” (Genesis 1:28). Adam was the first man (1 Corinthians 15:45), and Eve was the mother of all humans except for Adam (Genesis 3:20). All human life started from them. How could they be fruitful and multiply, unless they had both sons and daughters, and their sons married the daughters? This first marriage union was extremely fruitful!
The answer is simple. Both Cain and Seth married their sisters. There undoubtedly were many of them even before the birth of Seth and the reality is that there weren’t any unrelated females for these sons of Adam and Eve to marry.
Adam was 130 years of age when Seth was born (Genesis 5:3). After that, Adam lived 800 years, and “he begat sons and daughters.” The sense of the passage is that he continued begetting sons and daughters. That is a long time—as long as if some man and his wife living back in the 12th century had continued to live and continually bear children ever since, clear up to now, the 21st century!
How many children Adam and Eve conceivably had during their great life span of nearly 1,000 years is almost impossible for our minds to grasp in this fast-moving, short-lived world of one or two children to a family. It is hard for us to realize that Adam lived almost one-sixth of all the time from his creation until now. Yes, there must have been plenty of young women for wives for Cain and Seth, and all their many other brothers as the hundreds of years passed.
Remember also that it was not wrong to marry a sister or brother in the beginning. No physical harm would result. Over 2,000 years later, Abram married his half sister Sarah (Genesis 20:12). His brother Nahor married his brother Haran’s daughter (Genesis 11:29). There was no genetic harm to any children that would result from these unions. In fact, it is the way by which different races and racial characteristics were brought forth from the original human stock as God purposed. It was not until the days of Moses that God forbade brothers to marry their half-sisters (Leviticus 18:6, 11). As new generations appeared, mankind began to show definite racial groups and subdivisions. As men have become more racially distinct, it has become genetically harmful for close blood relatives to marry and to produce offspring.
Back in the antediluvian days, when people lived 700, 800 and 900 years, they did not age as we do today. They were able to continue to bear children, undoubtedly, for hundreds of years. After the Flood, due to human dissipation and living contrary to God’s revealed laws—His right way of living—the life span of man shortened.
By the time of Abraham, Sarah was considered too old to bear children at age 90, and Abraham thought it impossible for him to become a father again at the age of 100 (Genesis 17:17). Isaac was born as a direct miracle. But before the Flood, and in the days of Adam, it was different—and would be today—had not men departed from the laws of living revealed by God.
Recommended reading: Mystery of the Ages