Boy or Girl

There is a theory of determining the gender of a baby by renewal the parents' blood. According to the theory, the blood in men is renewed every 4 years, and in women - every 3 years. If dad's blood is "newer", then a boy will be born, if mom's - a girl. Thus, the baby repeats the gender of one of the parents whose blood was younger at the time of conception. 

Please note that the method used to determine the gender of a baby does not have any scientific justification or any official recognition in medical practice. Nevertheless, in most cases, the calculation result is accurate.