How to get inheriting class int members?

I have a base class like this:

public class Marker {
     public int[] GetChildMarks() {
          //Somehow Get Child int members
     }
     public int ShallNotBeInArray;
}

public class MyMarker : Marker {
   public int Size, Number;
}

public class TedsMarker : Marker {
   public int Power;
}

//... somewhere in main
var m = new MyMarker(){Size=3, Number = 666};
var arr = m.GetChildMarks(); // [Size, Number, Any other ints in MyMarker ]
var t = new TedsMarker() {Power=999};
var arr2 = t.GetChildMarks(); // [Power, Any other ints in TedsMarker] 

So is it possible and how one can do such a thing in C# using reflection?