Geneticists make new discovery about how a baby's sex is determined. Medical researchers have made a new discovery about how a baby's sex is determined: it's not just about the X-Y chromosomes, but involves a 'regulator' that increases or decreases the activity of genes which decide if we become male or female. Source 6a.
I guess that rules out all the old hag's tales about using certain positions, herbs and other traditions to bring about a certain gender.
The scientist thing is most likely a lie. I've always been taught about X chromosomes and Y chromosomes. I wouldn't be surprised if they invented a baby with multiple genders.