i hate to seem argumentative, but the ONLY time an "allergy is out grown" is if it was infact NOT an allergy just an intollerance.
One reason i say this is... a TRUE allergy means your body does not posess the enzymes and other chemicals needed to break it down properly. You CAN get enzymes(some) to assist with digesting certain things but not fully since your body also has chemicals which need to react approprietly with enzymes in the food itself(which are only present if the food has not been heated above[its] "body" temp)
Also, many people THINK they have "outgrown" an allergy simply because they didnt react badly to a small amount on a single occassion or didnt have the same reaction as previously. Most allergies which DONT have Hive or asthmatic/anafalactic type reactions will be slower coming on and often noone pays attention until the reaction is actually to repeated exposures. Additionally, if we dont "listen" to our body about something, it can change the message system and the brain will even send a signal as if from another are as another problem to get our attention.
For example, as a child i discovered I was allergic to dairy, I got very ill shortly after drinking milk or even a little bit of ice cream. in my late teen years, believing maybe i'd grow out of it, i tried some milk, no ill effect besides i thought it tasted horrid!!! so i had some icecream, and pizza (over a few days) and I had the worst stomach cramps, fever etc, i went to the hospital thinking I had appendicitus! in my mid 20's (not thinking about it much) i had icecream a couple days in a row on hot summer days and pizzza possibly with friends never thinking that they would have had normal cheese(i use "fake" cheese) and suddenly I realized i had been miserable with everyone, for no reason, I was snapping for no reason, nit picking and on everyones case CONSTANTLY. I stopped having the dairy and it went away, I was fine! a few days later to test the theory(warning everyone first) i ate cheese with everymeal and topped it off with icecream..... I was sssooooo miserable i sent myself to bed so i wouldnt ruin everyones evening, had to stay clear the next day too
My point being, allergies dont necessarily
PRESENT the same all the time and not necessarily with a random "oops" exposure
SOOO.. if you think you or a family member may have outgrown an "allergy" , be hopeful, and watch for OTHER changes, they could be ANYTHING, physical, mental, emotional, developmental...ANYTHING.