Casting an object to a generic interface

internal interface IRelativeTo<T> where T : IObject
{
    T getRelativeTo();
    void setRelativeTo(T relativeTo);
}

public class AdminRateShift : IObject, IRelativeTo<AdminRateShift>
{
    AdminRateShift getRelativeTo();
    void setRelativeTo(AdminRateShift shift);
}

IRelativeTo<>
IRelativeTo<AdminRateShift>
IRelativeTo<IObject>

IRelativeTo<IObject> = getObjectThatImplementsRelativeTo(); // returns Object

internal interface IRelativeTo
{
    object getRelativeTo(); // or maybe something else non-generic
    void setRelativeTo(object relativeTo);
}
internal interface IRelativeTo<T> : IRelativeTo
    where T : IObject
{
    new T getRelativeTo();
    new void setRelativeTo(T relativeTo);
}

void DoSomething<T>() where T : IObject
{
    IRelativeTo<IObject> foo = // etc
}

DoSomething(foo);

DoSomething<SomeType>(foo);

void MyFunction<T>(IRelativeTo<T> sth) where T : IObject
{}

interface IRelativeTo
 {
   IObject getRelativeTo();
   void setRelativeTo(IObject relativeTo)
 }

abstract class RelativeTo<T>  : IRelativeTo where T : IObject
 {
   public virtual T getRelativeTo() {return default(T);}

   public virtual void setRelativeTo(T relativeTo) {}

   IObject IRelativeTo.getRelativeTo() {return this.getRelativeTo(); }

   void IRelativeTo.setRelativeTo(IObject relativeTo)
    { this.setRelativeTo((T) relativeTo);
    }
 }

class AdminRateShift :  RelativeTo<AdminRateShift>, IObject {}

IRelativeTo irt = new AdminRateShift();
  IObject o = irt.getRelativeTo();
  irt.setRelativeTo(o);