I found it very tricky as plenty of factors make the answer accurate or not for the person who asks:
- Who is the person asking this question? and what is the person used to eat?
- Who is the person asked to? and what is the person asked used to eat?
However, when you don't know the person, it is quite hard. Yesterday night, I ended up eating in a Chinese restaurant here in Singapore. It was my first experience with the double boiling soup and it felt refreshing to be completely ignorant of what to order. Of the 2 soups we ordered to boil all of our food one was spicy but a neighboring Chinese customer told us it would not be so spicy. Sure enough, it was very spicy, even for my husband who is more used to spicy food than I am! (the dinner was delicious though - so no complain!).
So, how is our tolerance to spice determined?
I am not sure what it is, but I'm guessing is part of the food education we receive as kids. I have seen kids from Peru eating dishes or sauce I couldn't. Another example of how our palates are educated is my 2 year and a half niece eating blue cheese or any kind of "stinky" cheese while some of my friends can only tolerate spreadable cheeses. Nevertheless, our body also plays its part to our spice tolerance, and so it's not only acquire, it is also innate. That's a good news! It's not because you were not used to eat spicy as a kid that you will not enjoy it later and vice versa.
You can read more on spice tolerance factors on Popular Science, learn why a chili burns and what you can do to soothe the pain on I Fucking Love Science and train yourself to eat spicier with Serious Eats.