Coming from someone who studies divination in its many forms... I DO believe that it can work, given the right state of mind and with the proper control. My grandfather could also divine water with a forked branch. There's many forms of divination out there and many uses. Too write them all off as poppycock I think is rash. I'm going to split my chicks into 2 groups after they hatch based on my readings and see how accurate I am.
I personally think when it comes to divination people are not just guessing or are having divine intervention, but that they have taught themselves to look at all the clues around them to come up with an answer... It is not magic, just a good guess from a sensitive person that takes in all the clues that are apparent but unnoticed by others. That's my opinion anyway... When it comes to eggs I think it just has to be guessing! They are all the same. no difference in male or female? Now if it were the chicks after hatch I would say you could strike it rich being a chick sexer, that is if you are correct on your guesses. Let us know how it turns out yall who are going to swing the string.