Covariance and Contravariance in Task<TResult> CallActivityAsync<TResult>(string functionName, object input);

i am facing an issue while using CallActivityAsync with Covariance and Contravariance. Example:
If you have CallActivityAsync("RunFun",null);
this RunFun Returns List of child classes.
Base Class Ex: Human.
Child Class Ex: Male / Female.

When the CallActivityAsync finishes execution it return a list of BaseClass Correctly but items inside it also are BaseClass items not Male / Female items.