If you have always been allergic to peanuts, you will always be allergic to peanuts.
Yes, some chemicals can cause allergies to occur. It the environment that causes most allergies. A workmate of mine, his wife used to live off of almonds. One day she ended up being sent to the emergency room. She had almonds and her throat closed up and her face started swelling and she broke out in hives. She grew up on the stuff. She lived somewhere there were few pollutants around. Almost the back country. She moved to the city and her allergies developed.
Someone once told me that there are only two things that are real allergies. Peanuts and Bee stings. There rest are all just environmental wonders of city life. I believe it. I go out and spend weeks in the country, all my allergies disappear. Come back home, they are all back in full force.