the best resource I can point you toward is a show called "The Naked Archeologist" which is aired on the History International channel. Unfortunately the shows are not available on DVD and you may have to watch a number of the shows before they replay the one on his study of the Nephilim which comes from a Hebrew root word meaning "fallen" which can also have a connotation according to one of the meanings in my Hebrew lexicon of being less in some way. Sorry that I don't have a link, but this was the first I had heard of such a link, and according to the science noted here which is why I was seaching for information of possible physical evidence of homo sapien and neanderthal breeding, it is a plausible explanation of this passage.