Throughout history people puzzled over what exactly determined a whether a baby would be a boy or a girl. Theories tended to range from the woman's diet, to the ambient temperature of the room. Until one woman, studying mealworms, finally determined what was the difference between little girls and little boys.
A new and simple blood test can predict the gender of a fetus after just seven weeks of pregnancy. It's great for predicting gender-related diseases, but the specter of sex selection looms large.