Why do the Japanese always peel their fruit? 2nd attempt

My in-laws are convinced that it comes from the 70s, when Japanese chemical warfare on farm bugs (along with pouring pure chemicals into rivers etc) made the common complaints about Chinese imports today seem the nationalistic nonsense that it mainly is. My own theory, though, is that it goes all the way back to Edo times, where the lack of animals (most people never ate meat, milk products were unknown, most people were forbidden to ride horses) meant that the manure was almost always “night soil” (human excrement), with the consequent greater risk of the spread of diseases.