"25,000 people took this quiz: http://www.quiz-maker.com/QRVR3A. Their results have been analyzed and guesses have been removed. Control experiments were included that indicate people who are extremely confident in their answers are likely to get them right 95% of the time or more. This study mostly rules out memory and mishearing as the likely cause of the Mandela Effect. The actual cause remains unknown and worthy of further study."
Unknown? Hardly.
Unknown? Hardly.