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There was once this mad scientist named Glen Oliver Duncan who genetically engineered an animal which had the ability to understand speech and follow instructions.
The animal was designed so that it would have the natural instinct, or drive, to pluck fruit from plants whenever it was near such vegetation.
The crazy scientist, for some reason, told the animal, "If I find out you have been picking my fruits, I will set you on fire!" The animal heard these instructions and was very afraid. The animal tried its best not to pick any fruit, but eventually, after many years and despite it's best efforts, it gave into its natural instinct, thus the scientist set it on fire.