How to solve the Error: Inconsistent accessibility: parameter type for generic c# interface?

Question

On writting this code into my project i am getting the error that

Error 1 Inconsistent accessibility: field type \'System.Collections.Gene

Answer 1

Childrendata isn't public. How, then, do you expect someone calling addchild to be able to provide the required parameter?

The obvious fixes are to change the accessibility of addchild or Childrendata.