The original question was:
Since Adam and Eve only had the boys Cain and Abel, and Cain killed Abel, was the woman he took for a wife in Chapter 4:17?
Answer by John Mackay and Diane Eager
Genesis 3:20 gives us Adam’s faith statement that he named his wife Eve because she would “become” the mother of all living. Therefore, whoever Cain married had to be a direct descendant of Eve. Genesis 5 tells us Adam and Eve had sons and daughters. Therefore, Cain could have married a sister or a niece.
But you say this is incest, and would have made us all morons.
It is interesting to note that close family marriages were outlawed by God only at the time of Moses, and still are in most modern societies. They often produce defective offspring due to the mutations that all people now carry. Most of these are recessive, i.e. they don’t cause problems until a child inherits two copies of the defective gene. Close family members are likely to carry the same defective genes and therefore likely to give double dose of defective (sometimes lethal) genes to any offspring. However, in Cain’s day this would not have been a problem.
Genesis tells us the world was originally created very good, which means Adam and Eve were created with no defective genes. Furthermore, the environment as was also very good. There would have been none of the hazards that cause mutations these days. Therefore, the first few generations of the human race would have undamaged genomes and close family marriages would not have caused any genetic problems. We should also note that Noah’s family all intermarried with no great problems resulting, and even Abraham was married to his half sister Sarah and God didn’t hold that against him. It was only during Moses time when our lifespan had dropped well below 100 years on average, (a sure indicator of mutational build up) that we find God stepped in and forbad such detrimental marriages. But neither Cain nor his sister would have faced such problems.
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