Guest Author - Nicolette Heaton-Harris

There are plenty of different theories out there that tell you how you choose the sex of your child. Eating savoury foods say, or having sex at certain times and frequencies, but not a lot of these theories are very scientific!

Each human being has forty-six chromosomes, but when it comes down to the selection of whether you have a boy or a girl baby, this is just judged by two chromosomes.

An woman's egg has twenty-three and a man's sperm has twenty-three. But the chromosomes that governs the choice of which sex is finally created are called (X) and (Y).

Women's eggs each contain a single (X) chromosome and men's individual sperm have either an (X) chromosome, or a (Y) chromosome.

So, if an (X) sperm meets an egg, also an (X), then that baby will be a girl. (XX).

If a (Y) sperm meets an (X) egg, then you will have a boy. (XY).

(X) and (Y) sperm do have different characteristics however apart from sex selection. (X) sperm swim slower and live longer. (Y) sperm swim fast and dies quicker. This is why people are advised to have sex on the day of ovulation to ensure a boy and a couple of days previous to ovulation to ensure a girl.

Does this work?

Because if it does, then how does it explain women who get pregnant with twins that are a boy/girl combination?

And how do twins occur?

A woman can produce one egg or two each month, either from the same ovary, or from both. A single fertilised egg can split into two, resulting in identical twins that will always be the same sex. Two eggs fertilised will result in non-identical twins, whether they are of the same sex or not.