Where did Cain get his wife?

I'm honestly kicking myself for not putting this one up sooner, because it's one of the questions that most Christians freeze up on. And it's beccoming increasingly popular among skeptics. I was tormented with this ne all through high school, so pay attention. Chances are you'll face it too.

People often ask where Cain got his wife. And the answer is simple, if you have a proper grasp of Scripture and genetic science. But because the answer to this question is a little hard to swallow, I'm going to explain it before I actually give it.

First off, you have to understand that our DNA, like everything else in the physical universe, is in a slow-but-steady rate of decay. Due to radiation, carcinogens (chemicals that cause cancer, such as are found in cigarrette smoke and a lot of fried foods), and other factors, the human gene pool (in fact every gene pool) is gradually accquiring more and more mutations. Now contrary to what evolutionists will tell you, mutations as a rule do not cause improvements. In fact, just the opposite. Ever hear of sickle-cell anemia? Mutation. Cancer? Mutations. Birth defects, genetic disorders, and allergies? Ee-yup, mutations again.

Now it doesn't take a PHD in genetics to know that if these mutations, or flaws, are gradually building up, then if you go backwards in time you will find fewer and fewer of them. Ergo, eventually you would reach a point where there were few or none of them at all. Introducing Adam and Eve. When God made the world, He said loud and clear, "It is good." There were no mutations, no error or sickness of any kind until they ate the forbidden fruit. Ergo, Adam and Eve had perfect genes. If genetic science is at all trustworthy, they didn't even have allergies or acne.

Now, what does this have to do with where Cain got his wife? Well, the nice thing about mutations, which are by nature unhealthy (just imagine, for example, changing even one of the zeroes to a one or vice-versa in the startup codes on your computer), is that usually they show up in only half of a pair of genes. Remember, each parent only contributes half a set of genes. For example, let's say there were a gene which normally would read as "ABXYBA," but because of a mutation someone was carrying a version that read "ABYXBA." If that person married a person with the normal, healthy variant, their children would get one set of each gene, the healthy one and the unhealthy one. Most of the time when this happens, the healthy gene overrides the unhealthy one.

But, when two individuals with similar mutations have kids, their children are much more likely to inherit genetic disorders, diseases, or even vulnerability to some non-genetic diseases (for instance, some are naturally immune to one disease, but not another). And who would be most likely to share the same mutations? That's right, siblings. From the Biblical account we can be sure Cain's wife was his sister. Now, most unbelievers will condemn the idea of Cain marrying his sister (even though there was no one else around to marry) and use it as a reason to dismiss the Bible as unscientific. But if you actually look at the science, it backs up the Bible rather than fighting it. Cain and his sister both would have inherited genes from their parents which were just about as good as Adam and Eve's own genes (there is some disagreement as to whether mutations began to develop right at the Fall or after the Flood, when solar radiation became more intense). It would have taken a couple of thousand years for enough mutations would have built up to make sibling marriages a problem. And at around that time, we find the book of Leviticus forbidding incest, meaning that prior to that point it was not immoral for God's people to marry within their own families. Incidentally, if someone says that it was immoral for Cain to marry his sister, they're mistaken for this and one other reason: if they wish to discredit the creation account, and by extension the Creator God, who is there to say that anything is immoral at all?