How do I select from the children of a class from the GUI?

I want to be able to select from the children of a class in the GUI.
Like so:
14876-selectability.png
The little option boxes appear when it is a child of MonoBehavior, however they are useless because it won’t let me select to use AbiliyEffect or its children. Which I want to select its children, but when it is independent (a base class) it doesn’t show any selection boxes at all.
Code:

    using UnityEngine;
    using System.Collections;
    public class AbilityEffect:MonoBehaviour
    {
    
        public void Activate()
        {
        }
    }

    public class AbilityInv {
        [SerializeField]
        public List<Ability> AbilityList;
        public Ability[] EquippedAbilities;
        [SerializeField]
        public List<Ability> OwnedAbilities;
        void Start()
        {
            EquippedAbilities = new Ability[3]{AbilityList[0],AbilityList[1],AbilityList[2]};
            OwnedAbilities = AbilityList;
        }
    }
    [System.Serializable]
    public class Ability
    {
        public string AbilityName;
        public AbilityEffect abilityEffect; 
    }

Solved: monodevelops can only select other monodevelops from the GUI and they must be dragged into the child object first in order for them to be selected.