gistfile1.txt

using System;

namespace ConsoleApplication1
{
    interface ITest
    {
        void Method();
    }

    class Parent : ITest
    {
        void ITest.Method()
        {
            Console.WriteLine("Parent");
        }
    }

    class Child : Parent, ITest
    {
        void ITest.Method()
        {
            Console.WriteLine("Child");
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            var c = new Child();
            Parent p = c;
            object o = p;
            ((ITest)c).Method();  // Child
            ((ITest)p).Method();  // Child
            ((ITest)o).Method();  // Child
        }
    }
}