So you’ve decided to have a baby, and you wish you could tip the odds in favor of a certain sex. Maybe you have a house full of boys who are just desperate for a little sister to pick on. Or perhaps you want a strapping young lad to carry on the family name. No matter what the reason, getting to choose the gender of your baby sounds mighty appealing. But is it really possible to increase your odds of having one or the other? Some doctors and scientists say yes … and it’s as easy as creating the right circumstances at conception.

What determines a baby’s sex?

A baby inherits two sex chromosomes from its parents: one from its mother, who always contributes an X chromosome, and one from its father, who can contribute either an X or Y chromosome. Therefore, it is technically the male who determines the baby’s gender. If the baby ends up with two X chromosomes, it will be a girl; an XY chromosome, and there’s a boy in the making. Roughly half of the father’s sperm is “male” – or Y-bearing – sperm, and the other half is “female” X-bearing sperm.

So how can you possibly influence which sperm fertilizes the egg?

This is where the methods of gender selection come into play. There are currently two prominent theories on low-tech sex selection, proposed by Dr. Landrum Shettles and Elizabeth Whelan, Sc.D. Unfortunately, their methods contradict each other, so it confuses things a bit. Let’s take a look at each theory.