If the parent ate a peanut butter sandwich and then kissed the child near the mouth the child could have reacted. I know of a nine month old that was allergic to almonds - found out because mom mixed the last of the honey nut cheerios in with the plain ones and served them to the child for snacking. Child was then referred by doctor for allergy testing and came back positive for almonds, negative for other nuts but given epi pen and told to keep him from all nuts until he could be retested at age 2 when tests were more accurate.

If the reaction is gut as in loose stools, excessive gas, cramps it is considered an intolerance. If the child swells around the mouth it is considered an allergy and potentially anaphalactic because the swelling could block breathing.