Wow. Things like this always remind me to be thankful for having normal health. I'm not allergic to anything. It's hard to imagine dying from peanut butter.
According to an allergist I saw on TV over the weekend, one can be allergy free, then in a later stage of life, develop an allergy. Yikes!
Echoing Salvey, you never know when it could happen. Not all people with severe allergies were born that way, or even developed the allergy early on.
I am allergic (well, I don't know if it counts as an allergy, but it burns like hell now) to alluminum zirconium (whatever the heck the thing in 99% of anti-persperants is called). It just happened one day when I was 26 years old...I put on the same Right Guard Sports Stick as I had for the longest time, and POOF, my armpits were ABLAZE! I had to spend 30 minutes in a cold shower just washing and scrubbing to make it stop hurting. You won't realize this until it happens to you, but geometrically it is impossible to get both armpits under the cold water at the same time...some kind of space-time thing :-(
Funny (ha ha) thing is that it took 1 more day for me to realize what was going on...the next day it was the same thing!
Now I either have to go stinky or look for the rare product that uses Aluminum Chloro-something. Ban Classic used to be my only choice, but now that one isn't around...but I digress...