Science Friday - Sex Edition

Let's talk about sex. No, not that kind of sex. I mean let's talk about gender. No fewer than 8 of my friends are currently pregnant. Speculation abounds as to who's having what - a boy or a girl, that is. With all the old wives tales floating around out there, I feel that as a scientist I am obligated to shed light on the biological side of the issue. So without any further ado (drumroll please...), the father alone determines the sex of the baby. Yes, it's true. You can either thank or blame your child's father for the gender of your baby. 

Scanning electron micrograph of a human X chromosome

Think of it like this. We all know that we inherit half of our chromosomes from our mother and half from our father. We also know that our sex chromosomes determine our gender and that 2 X chromosomes (XX) make a female, while having 1 X and 1 Y chromosome (XY) makes a male. So, when your parents' chromosomes were being divided up, your mother could only give you an X but your father could either give you an X or a Y. If he gave you an X, you would be XX = girl. If he gave you a Y, you would be XY = boy. Note - the color represents which parent you got the chromosome from. Red represents the chromosome you got from your mom and blue represents the chromosome you got from your dad.  

Yes, all science humor really is that bad...