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Yes Your Toddler Really Is Smarter Than A 5-Year-Old
Developmental psychologists are trying to figure out what very small children know and when they know it. The answer: a lot, and a lot earlier than you think. One experiment finds that 18-month-olds can reason abstractly when sorting blocks, well before they are able to explain it.
Source
In my opinion, I really think this is only based on the type of person it is. Some are more faster and smarter than others because of how they operate, and we cannot really "Read minds" so we will never know for sure if some of those kinds of theories are true or not.