How probable is the Genesis theory of Creation?

In my opinion, not very likely.

It is such a descriptive, and by modern standards, non-scientific...even poetic...description, it is impossible to gauge its validity.

Considering that God created the entire universe, and all the physical and biological laws that go along with this system of matter and energy, it amazes me that only a few hundred words are reserved in the Old Testament to describe this process, and those words are written in a horribly ambiguous style. The Old Testament was written by at least four different people, or chroniclers, and none of them were inspired observers of the physical world. If we subject their writings to a simple elementary school science test, they would all have failed miserably...but their knowledge is entirely appropriate for the times in which they lived ca 1500 BC or earlier by most accounts.

Of course, you can parse the words in the story...there are actually several different accounts of Genesis in the Old Testament...and compare them to modern scientific ideas, but this is very much like the Rorsach ink blot test.