Where DID Cain get his wife????????
Most Christian scholars will agree that Cain married his sister. This can sound barbaric and sinful until one realizes that if Adam and Eve were the first created humans then they were without genetic defect. Laws against incest today are enforced because all of us carry around at least four or five lethal or harmful mutations but you need two copies of the gene, not one, for the defect to be expressed. Since brother and sister are from the same parents there is a very good chance that these genes will get paired up in any offspring between the two. But this would not have been the case with Adam and Eve's children for they carried no inherited mutations. Remember that even Abraham, at least twenty generations later, was still able by law to marry his half-sister. Sarah was the daughter of his father but not his mother (Genesis 20:12).