With our third kid coming, a lot of conversation revolves around gender. Since we have two boys already, we researched sex-picking. There are a lot of crazy theories out there. Really dumb ones. Unless they involve modern scientific techniques, I dismiss them. I don’t need to listen to the details to know they’re wrong.
Consider: This is a special time and place. In modern day America, there is no right of succession. There is no primogeniture (one of my favorite words). There are no dowries. Girls can succeed in life just as easily as boys. There is no societal reason to prefer boys over girls.
But throughout most of human history, the opposite has been true. For tens of thousands of years males were preferred. The fate of kings and empires rested on the ability to produce healthy male children. Even today, it is common in much of the world to kill female infants. The incentives are enormous to find a way to influence the baby’s sex.
Across the globe, over tens of thousands of years and billions of births, I am confident that if any method existed, it would have been discovered. If it was as simple as using a certain position, or nutrition, or the right mate, or the time of month, we would already know about it. The fact that we don’t tells me that none of that is true.
So if you want to talk about DNA, or sorting sperm in a centrifuge, or anything modern, I’ll listen. Anything else, I’ll give you a polite smile, but I’m not really paying attention. It just ain’t so!
(On a tangent, there is some weak evidence that some species, possibly including us, can change the male/female birth ratio in response to environmental pressures.)