That would make Cain's wife Cain's sister. No wonder they skipped this in Sunday School ...
Many people immediately reject the conclusion that Adam and Eves sons and daughters married each other by appealing to the law against brother-sister intermarriage. Some say that you cannot marry your relation. Actually, if you dont marry your relation, you dont marry a human! A wife is related to her husband even before they marry because all people are descendants of Adam and Eveall are of one blood. The law forbidding marriage between close relatives was not given until the time of Moses (Leviticus 1820). Provided marriage was one man to one woman for life (based on Genesis 1 and 2), there was no disobedience to Gods law originally when close relatives (even brothers and sisters) married each other.Remember that Abraham married his half-sister (Genesis 20:12). God blessed this union to produce the Hebrew people through Isaac and Jacob. It was not until some 400 years later that God gave Moses laws that forbade such marriages.
So what?