I am always looking for new information to expand and broaden my views, and this subject lent itself well to expanding my views. Here is my opinion based on the information I have: 1) Someone has patented a computer readable medium with a program to determine the sex of an egg by it's shape. This could explain why commercial hatcheries aren't using the method. The patent expires in 2022 and I'm guessing this will change things. http://www.patentstorm.us/patents/7167579/claims.html 2) Mother Earth News wrote an article on this in 1974. http://www.motherearthnews.com/sustainable-farming/buying-fertilized-chicken-eggs-zmaz74zhol.aspx Additional articles on the subject have been published for many years, but they are all case studies such as this. 3) I have yet to find an empirical, research based study that would substantiate a false hypothesis correlating egg shape and sex (for the over-educated skeptical people in the crowd such as myself). Certainly someone somewhere has studied this, but where is the published study? 4) Researchers have recently (2009) discovered the genes and sex chromosomes in birds: http://chickenoreggblog.wordpress.com/2009/09/11/bird-sex-gene-identified/#more-347 . We now know the answer to the riddle: which came first the chicken or the egg? Science now knows the chicken came first. It was long believed the egg came first. 5) Scientist believe it is the pressure exerted on a hens egg while she is laying that determines the shape of the egg. That is logical, but doesn't go far enough. We know that genes do influence the hardness or pliability of an egg; different breeds lay different eggs with varying degrees of "hardness". Egg shell pliability is influenced by the genes specific to a particular breed. We know this to be true, it is empirical, research based information. Pliability of the egg shell will determine egg shape. This is simple physics. The more pliable the egg shell the more pointed it will be after the hen has exerted pressure on it. The harder the shell the less likely it is to change shape. That is, a hard egg shell will retain its original oval shape after the hen exerts pressure. Why would a female egg need to be harder? What benefit would that have to the species? To perpetuate a species fewer males are needed than females. A hard shelled female egg would be more likely to survive. In summary, my educated opinion is this; some breeds of chickens can produce eggs that can be "sexed" to some extent. That is, a statistically significant number of eggs will be male if pointed, female if oval. As in all of nature there are variations and exceptions to every rule. Have fun and try to count your chickens before they are hatched. What could it hurt? Don't be surprised if someone has a lot of eggs that can be sexed. "It's in the genes."