Thank you for your query.
Do not worry at all. This does not necessarily relate to physical disease. I think it is a choice.
If he doesn't want to eat spicy food why do you need to give him spicy food? Ask him if he has any trouble eating spicy food like hurrying bowels, stomach burning, allergy
etc? You will get an answer.
Different people have different choices.
Spicy food usually causes a lot of problems.
if you still persist,try starting out with tasty food like pizza or burgers then move on to different other kinds of food.
Make your spicy dishes more tasty.
I think that over the years his taste is going to change too.Maybe he will relish spicy food.
Let him take his time to develop his sense of taste.
If you have any further queries you are free to consult me.
Hope this answers your query.
Wishing your child a spicy tongue.Have a nice day.