Genesis Creation Stories: Sequence Contradictions?

Hi...I've read all the posts here with great interest. I'm new to this forum and am not sure if my post "goes" here or should be a new thread. It does concern Genesis Creation Stories: Sequence Contradictions? but not the ones that have been discussed.Can someone explain the following:In Genesis, Chapter IV, verse 16, after killing Able, Cain "went out from the presense of the Lord, and dwelt in the land of Nod, on the east of Eden." Verse 17 says, "And Cain knew his wife, and she conceived, and bore Enoch; and...." Then, verse 25 says: "And Adam knew his wife again, and she bore a son, and called his name Sheth; for God (said she) hath appointed me another seed instead of Abel, whom Cain slew."If Adam and Eve were the first people God created and if their first children were Cain and Able and if Adam 'knew his wife again'(AFTER Cain "went out from the presense of the Lord, and dwelt in the land of Nod, on the east of Eden") and the resulting son, Sheth, was a replacement for the loss of Able ...and if Cain took a wife in Nod, who, then, did Cain marry? More to the point, who were HER parents? It would seem that, at best, Cain's wife, while not named, had to have been a sister.I don't mean to offend, but it seems to me everyone must have been committing incest. However, the contradiction I see is that 'Adam knew his wife again' after Cain went to Nod. Therefore, there couldn't have been any women for him to marry when he was there.Does anyone know what Biblical experts say about these issues? (Incest and/or how Cain could have married in Nod?) Does anyone here have any comments?prattie