She couldn't have been his sister, since he married and THEN Adam and Eve had more kids.
If you kept a journal of everything you did in your life, how many journals would you have right now? How many if everyone who ever lived did the same? The Bible distills history, beginning to end, in a relatively few amount of pages. It doesn't have time to go through eVERYTHING, and that's why, as a rule, scientists are against it. After all, it doesn't say that God didn't create other people, does it? God gave him the Mark so that no one would kill him, then sent him off to Nod. Therefore God knew about those other people, and therefore, logically (you';re a NINJA for goodness sake!) He would have created them too, n'est pas?
Gingers: disturbing the dreams of decent folk since the dawn of time.
W.A.S.T.E.