Generic interface property is virtual in implementation

I have a model called 'Entity' which implements 'IEntity' interface as follows (simplified):

public interface IEntity<T> where T : IComparable
{
    T Id { get; set; }
}

public class Entity: IEntity<Guid>
{
    public Guid Id { get; set; }
    public Guid LayoutId { get; set; }
    public virtual Layout Layout {get; set;}
}

I would like to clone an object of this 'Entity' model while ignoring virtual properties as follows:

public static class CloneHelper
{
    public static T CloneNonVirtual<T>(this T source) where T : class
    {
        var cloneObj = Activator.CreateInstance<T>();
        foreach (var prop in source.GetType().GetProperties().Where(w => w.CanWrite && !w.GetAccessors().Any(x => x.IsVirtual)))
        {
            var cloneObjProp = cloneObj.GetType().GetProperty(prop.Name);
            cloneObjProp.SetValue(cloneObj, prop.GetValue(source));
        }
        return cloneObj;
    }
}

Here, the problem is that LayoutId's accessors are not virtual, but Id's accessors are! Please see both QuickWatch windows:

Why does this occur? Is this because Id is an implemented property of the generic interface 'IEntity'? If so and if this is intended behavior, why?

Thanks,

Ferit