Genesis claims that there were exactly two humans in the beginning: Adam and Eve. One of their sons was Cain. Genesis mentions he had a wife. Now where did she come from?
She must logically have been another child of Adam and Eve. But doesn’t Christianity condemn incest for obvious genetic reasons, and very rightly so?
I found a very logical explanation at ChristianAnswers:
Adam and Eve did not have accumulated genetic mistakes. When the first two people were created, they were physically perfect. Everything God made was “very good” (Genesis 1:31), so their genes were perfect—no mistakes! But, when sin entered the world (because of Adam—Genesis 3:6, Romans 5:12), God cursed the world so that the perfect creation then began to degenerate, that is, suffer death and decay (Romans 8:22). Over thousands of years, this degeneration has produced all sorts of genetic mistakes in living things.
Cain was in the first generation of children ever born. He (as well as his brothers and sisters) would have have received virtually no imperfect genes from Adam or Eve, since the effects of sin and the Curse would have been minimal to start with (it takes time for these copying errors to accumulate). In that situation, brother and sister could have married with God‘s approval, without any potential to produce deformed offspring.
By the time of Moses (a few thousand years later), degenerative mistakes would have built up in the human race to such an extent that it was necessary for God to forbid brother-sister (and close relative) marriage (Leviticus 18-20). (Also, there were plenty of people on the Earth by then, and there was no reason for close relations to marry.)
This fits very well with the scaringly high mutations numbers observed by Dr. Sanford. and other population geneticists.
It will stay interesting to observe how the discoveries of geneticists shake up the scientific chronology we’ve been told. Watch this: scientists are starting to invent epicycles to save their evolutionist worldview – which can’t survive with the observed high mitochondrial mutation rate – mitochondria mutate more than 10 times faster than standard evolutionist chronology can accept:
(as usual I use the wikipedia to assess the current account of atheist government science).
Like the scholastics I hold that contradictions between Biblical and scientific account must be resolved; that that is the goal of science. We can safely say, this hasn’t happened yet.