Intelligence is a self-made thing that is acquired through practice, hard work, and mentors. Schools or degrees help teach a person the basics needed to be smart, sometimes being a good reader/lecturer counts as being smart. It's not something made up of DNA that can be passed down from your parents, every normal person is born with it.
It depends on people what their measure of intelligence is, a scientist can be considered intelligent, and a businessman can also be considered intelligent because he knows how to deal with customers and so on. A scientist or businessman has learned the basics through the education he received at school but his experience in the field helps to broaden his mind.
A person who talks a lot or talks less and answers all questions can be considered intelligent. It was something he learned through his parents in his childhood, that parents are the most important for a child to be confident and intelligent. All children learn their basics from their parents and react as they were fed by them.
I was watching the movie "Lal Singh Chadha" where they showed how a mother made a disabled child out of his disability into a good person and a successful businessman. His mother never let him down because of his disability and never let him think that he is not like others. He always taught him that he could do everything that others could do, which forced his mind to think like a normal human being. He became not only a successful person but also a kind person who loves to take care of others.
The same story I read about a scientist not sure if he was Edison or not but the bottom line was that his school sent a letter to his mother where they wrote that his child is very incompetent in studies and we cannot teach him anymore but the mother told his son that the school has sent an apology letter saying that your son is very intelligent and we are unable to teach him. She became his teacher and raised him as a scientist who made a great invention and was awarded the Nobel Prize.
A good upbringing is the most important part of allowing him to be intelligent, once his brain is fixed, schools help teach him the basics of how real life works. His mind begins to expand and he begins to think of something unique that makes him seem intelligent in the eyes of others, but in reality, he was doing something that his mind was too trained for.