A child can develop a penicillin allergy at age two, even without prior exposure, if exposed to penicillin through cow's milk contaminated by agricultural practices.

“my wife had a very bad infection and so he had to be bottle-fed after the first month of life and so he had cow's milk for a long time nothing wrong with that kids always drink cow's milk but cow's milk is coming now with penicillin in it because the agricultural industry treats penicillin so he developed an allergy to penicillin”