Actually, I have a very unusual story. When I was a kid I had lots of summer allergies due to pollen and grass (a lot of allergies to the point that I went to an allergist). This all abruptly ended when I was about 12 when all of my allergies stopped. I attribute it to exposure since I would constantly go outside and play in the garden, plant a lot of stuff, play in the grass even though it would make me get rashes and sneeze. Eventually after enough exposure the allergies stopped.