What does it mean to be “smart?”
Healthy infants (99 % of population) may have slight deviations in the potential of smartness, but the actual level of being smart mostly depends on one and one thing only – LUCK!
An ability to run has its own physiological basis - legs.
An ability to reason (a.k.a. being smart), also has a specific
physiological basis - a developed brain.
Everyone has a brain, but, when we are born our brain is not developed yet, it is just potentially developed, and the level of brain development depends a lot on a good luck one has.
A good luck means - when and where one was born, his/her parents, friends, teachers, and it is mostly responsible for who one will become in his or her 20s (the rest will be up to him or her). For example (more in: https://www.smashwords.com/books/view/665204), since I was little my parents tried to teach me reading, chess, music; I have not become a chess master or a musician, but those lesson definitely help my brain development (and I have no responsibility for that – just was being lucky).
Knowledgeable people are the basis of a society, they are responsible for a stable functioning, they preserve existing traditions, and sometimes they may object even progressive changes. However, smart people can outsmart knowledgeable ones (like Russian FSB outsmarted American CIA, FBI and NSA in 2016)