I received the following question:

Who was Cain’s wife?

Cain’s wife was, quite simply, his sister. I know that sounds awful to us today, but we need to realize several facts about the matter.

1. Who else was there to marry? You’ve heard the old expression about the “last man” or “last woman on earth.” Well, if there really were no other men and women on the earth than your sisters, of course that would be who you would have to marry.

2. There would be no genetic problems with intermarriage that close to the Creation. The fact is that the biggest physical reason we can’t marry within the family is that our genes contain various mistakes or mutations. Many of these mutations are recessive…that means that as long as you get normal, healthy genes from the other parent, the mutated genes you get from one parent do not affect you. Of course, sometimes one is unlucky enough to have two parents who both have the same bad gene, and then the baby is born with problems. But the big problem with marrying your sister is that the chances of both of you having the same mutated genes are very, very good. Thus there is a really big chance that your babies would be born with physical problems.

But, return with me in your mind to the time right after Creation. Adam and Eve contained no mutations at all…they were created perfectly! And so all the mutations we have now have developed as the result of mistakes that have happened in copying genes since then. These mistakes would have taken many generations to occur and accumulate. Thus, the children born immediately to Adam and Eve would have had no mutations, or at least none in common. If one child accidently was born with a recessive mutation, the chances are almost nonexistent that his sister also would have the same mutation. Thus there would have been no problem whatsoever with brothers and sisters marrying. There were no shared recessive mutations to bring out!

As time went on, mutations would have occurred. Thus, at the time of the flood, there would have been mutations in the gene pool. Then, when cousins and siblings were forced to marry each other after the flood, these bad mutations started to come out, causing the average lifespan of humans to decrease more than tenfold!

3. There were no incest laws in the beginning. There is no mention of such a thing until the law was given to Moses. In fact, Abraham married his half-sister. In our day, marriage to a sister or half-sister is against God’s law. But before He made that law there was literally nothing wrong with it. We should not read a law that is necessary and in effect today into the past when it was not in effect and not necessary. There was nothing wrong with incest before Moses!

4. If there were no incest laws and no genetic problems, marrying your sister would make perfect sense. Think about it. You would have grown up with her, and thus would share the exact same background, the same family traditions, and the same ideals. You would already know how well you got along, so you would know exactly whether or not you would want to spend the rest of your life with her. You would start off your marriage already knowing each other extremely well, and many of the problems of attempting to integrate two personalities together would have already been dealt with. Thus, if it were not for genetic mutations and the laws against incest, marriage with siblings would be almost an ideal. Today, however, there are such problems and such laws, and so we think of doing something like that as wrong and “gross,” and that is good, because that is how it should be. That is not how it used to be, however, and we should not read the situation today backwards as if it had always been that way, because it wasn’t.