Counter-anegdote. I grew up in the countryside, I am allergic to hay, pollen, dust mites, cat and horse saliva, and more.
I moved to a big city when I was ~20 and my symptoms got better, but I'm still allergic to all that - it's simply not putting me in hospital anymore.
Doctors told me most people grew out of the worst symptoms over time.
BTW I also somehow got allergic to kiwi fruits between primary school and my late 20s. I ate them rarely and at one point I found out they make me throat swell like a balloon. Didnt' happened before.
I moved to a big city when I was ~20 and my symptoms got better, but I'm still allergic to all that - it's simply not putting me in hospital anymore.
Doctors told me most people grew out of the worst symptoms over time.
BTW I also somehow got allergic to kiwi fruits between primary school and my late 20s. I ate them rarely and at one point I found out they make me throat swell like a balloon. Didnt' happened before.