Sherwyn Sarabi, from Barnsley, South Yorkshire, is ranked among the top 1% of cleverest people in the world after tests revealed he had an IQ of 136.
His mother, Amanda Sarabi, said she was really proud of her gifted son, who she described as “amazing”.
Sherwyn — who has a reading age of six — began speaking at the age of 10 months and was talking in sentences at 20 months.
By the age of two, Sherwyn could read, count to 200, recognise and name countries, flags, planets in the solar system, parts of the body, and internal organs.
Ms Sarabi, 36, a former teacher, said her son could point out every country in the world on a globe and match it to its flag. He could also explain the function of each internal organ.
She said: “His general knowledge is amazing. He knows about everything.
“It’s not like talking to a three-year-old. He doesn’t even watch children’s programmes, he watches the news. The weather is his favourite, especially the world weather. He loves that.
“We take every day as it comes. I’ve never forced teaching anything on to him.
“If he comes to me and asks me about a topic, I teach him to the best of my knowledge. Sometimes I have to look it up because I don’t know the answer but I explain it to him, then he’s happy.”
Ms Sarabi said she and her husband, Davoud, 37, who was studying construction management until he was involved in an accident, were well-educated but “nothing extraordinary”.
She said they first noticed Sherwyn’s interest in learning when he was 18 months, but his intelligence seemed normal to them until other people pointed out how unusual it was.
After his third birthday, Sherwyn was tested on the Wechsler Pre-School and Primary Scale of Intelligence, which placed him in the 99th percentile with an IQ of 136.
The normal range using this test is between 85 and 115, with the average IQ being 100.
Sherwyn has now joined the high-IQ society Mensa, which has only some 100 members aged under 10 out of 22,000 members across Britain.
Sherwyn has also started attending the Rastrick Independent School, in Brighouse, West Yorkshire, where a special lesson plan has been designed for him.
Ms Sarabi hopes he will now go on to achieve exam success at an early age and go to university.
She said: “Sherwyn is doing brilliantly. I’m so proud of him. I’m just happy to see him so happy at the school he’s going to.”
John Stevenage, chief executive of British Mensa, said: “Mensa are pleased to welcome Sherwyn to the society.
“As a bright child with great potential, we hope he will thrive with the Mensa network as support.”