using System;

public class Program

{

    public static void Main()

    {

        var arch = new Arachide(){id = "ouiii",arachideId="noon"};

        var basePeanut = (BasePeanut)arch;

        var amande = (Amande)basePeanut;

        Console.WriteLine(amande.id);

    }

}

​

public class BasePeanut {

    public string id { get; set; }

}

​

public class Arachide: BasePeanut {

    public string arachideId {get;set;}

}

​

public class Amande: BasePeanut {

    public string amandeId {get;set;}

}