There once was a mad scientist who lived atop the highest mountain in the land. His ambition was to make a perfect clone of himself, artificially aged to resemble him exactly.
He succeeding in this, but when his newly-made twin stepped out of the cloning chamber the mad scientist discovered his fatal flaw. He made the duplicate physically identical, but the clone had an extraordinarily different personality.
The scientist was mad, but he also happened to be polite, well-spoken and well-mannered. The clone however was ill-tempered and a spout of constant profanity whenever he spoke.
The scientist was so offended that he chased his clone around the mountaintop with a scalpel. During the chase the clone lost his footing and fell to his death!
The scientist came down from the mountain laboratory and was immediately arrested for making an obscene clone fall.