using System;

public class Program

{

    public static void Main()

    {

        var a = new Foo<int> { Bar = 1 };

        var b = new Foo { Bar = "Hey" };

        Console.WriteLine(a.Bar);

        Console.WriteLine(b.Bar);

    }

}

​

public class Foo<T> 

{

    public T Bar { get; set; }

}

​

public class Foo : Foo<string> 

{

}