I would say the tone of this sentence is formal.
No one is born intelligent. People can be intelligent by training their brain. People can use their weaknesses and use that to grow. Learning and studying is one way to become intelligent. People who hone their skills to their advantages can become intelligent too.
1. he said he was an aerospace engineer
2. she says she works in the National History Museum
3. the Doctor said their son studies at university
4. the Astronaut said they are in space
5. He says he teaches physics to his friend
6. Mother says she loves the youngest girl