Quadruplets Are Just As Rare
It has been discovered that quintuplets are born in the Czech Republic only once every 480 years. The chances of having quadruplets there are only one in seven million. They then decided to look at statistics around the world.
Vitro Fertilization
It is usually rare to give birth to quintuplets and fertility treatments like In Virto Fertilization is usually involved. However, Alexandra’s babies were conceived naturally, so the answer is likely found in her genes.