Yes, it's true. We may not want to believe it, your neighbors and relatives may tell you differently, but it's a scientific fact. Here's why.

There simply isn't any known physical way that men can have more X or Y sperm. The way sperm is made (spermatogenesis) is that in a man's body, undifferentiated cells called germ cells divide into two halves and these two pieces go on to develop into sperm in the testicles over the course of 72 days. Men's bodies are made up entirely of XY cells, including their germ cells. When these germ cells divide into two pieces during a process called meiosis (the 46 chromosomes in your husband's germ cells split in half to grow into sperm with 23 chromosomes, that will later combine with the 23 chromosomes in your egg to make a darling little 46 chromosome person for you to love) half are X and half are Y.

There are companies out there who are very happy to take your money to analyze your husband's sperm. Many people have gone this route. You may have even heard of people who had somewhat different amounts of X and Y sperm. But never has the man been found who produced substantially different proportions than 50-50, and most scientists believe that any variation in number of sperm is because of luck, a sample just happens to contain some more X than Y sperm - obviously, it would be highly unlikely that any man's sample would contain precisely or even in the ball park of exactly the same number of sperm in any one sample. So even if your husband had his sperm analyzed one day, it doesn't mean that tomorrow he wouldn't give a sample that would be the exact opposite. DON'T WASTE YOUR MONEY ON HAVING YOUR HUSBAND'S SPERM ANALYZED TO SEE IF HE MAKES "MORE" OF ONE TYPE OF SPERM THAN ANOTHER. He doesn't. He can't. XY divided into two, yields X and Y.

You may have heard a study in the news recently that purported that researchers had found a "gene" that made men produce more X or Y sperm. Here's a link to an article about this "study".

In this study, researchers went back and counted the number of male/female offspring in several families, dating back many generations. They found that yes, indeed, some families did have more sons/daughters than would be statistically expected, and that this was in some way connected to males. Men with more brothers tended to have more sons, and men with more sisters tended to have more daughters. That's it. That's all they discovered. It is certainly interesting and meaningful, but they never found any such gene. They never counted any of these men's sperm to even see if they had more X or Y sperm. Most of these men are long dead. They just GUESSED that they did. The part about a gene and differing numbers of X and Y sperm was entirely speculation on the part of the researchers. No such gene has ever been found. The media latched onto the bit about the gene, which has not been proven to exist and and probably never will, and reported it as fact when it was not even really an educated guess.

It's highly likely that the researchers are confusing environmental factors for genetic ones. Reputable science has shown that things in a man's environment such as profession, financial status, weight, diet, even the type of underwear a man prefers or whether he rides a bike, do indeed alter the gender ratio of his offspring in statistically significant ways. Relatives tend to share not only genetics but also environment. In light of the fact that men HAVE TO MAKE equal numbers of X and Y sperm because XY divided in two yields equal numbers of X and Y, I think that this study must be viewed as support for the idea that environment DOES alter gender ratio, rather than the supposition that there is some mystical gene out there that causes the laws of mathematics to somehow no longer function.

Now, all that having been said, does the undeniable fact that men make equal numbers of both X and Y sperm mean that their X and Y sperm are equally long-lived, well-developed, healthy, strong, fast, and able to penetrate an egg? No, it does not. It's well within the realm of reason that some factor, genetic, environmental, either or both, could affect a man's X and Y sperm differently, make one more likely than another to win the fertilization race. But in terms of proportion, the best science indicates strongly that ALL men make 50-50 X and Y sperm and don't let anyone tell you different!!!