People with special constitutions were extremely rare. Only four other families in four different countries had the ability to produce them. This was one of the reasons why their family was regarded as the most respected in the biological community and throughout the world.
The four countries with those families with special constitutions were all at the top of the hierarchy and the most powerful families. It was also because of this that the children of the Wen Family would undergo tests and be taken into the Secret Association. This is to better understand their strengths and talents, as well as undergo training until a certain age. They rarely stay with their parents. Of course, not all descendants of the five families were born with special traits. Some were just normal.
