Whether you believe in the creation story or not it's always good to do a bit of research. Here's something I've found on the origins of the Hebrew stories of creation.
When Abraham left Ur in southern Mesopotamia he would have taken with him the local myths and legends. After he had his epiphany he started his own sect using these older myths as a source.
One myth example is the epic of Gilgamesh. Here are some of the creation story similarities.
Paradise gardens
A tree of Life
Eating from a tree of knowledge
After eating from the knowledge tree, putting on clothes, not wanting to be naked
Having to sweat and toil the land
Blood being the essence of life
First son going east to a city
The garden being in the east
A Flood
There is plenty of research material on this, I good place to start would be:
http://www.bibleorigins.net/genesisgenesis.html
steve