Let your husband prepare two types A and B. Let him feed you in this order for 20 days A B A B A B A B A B A B A B A B A B A B Let him feed your son in this order for 20 days B A B A B A B A B A B A B A B A B A B A (Neitehr your son nor you know the sequence you take)
You and your son write down assessment on each day.
AT teh conclusion of the study, compare assessment between A and B.