The definition of "genius" is a person with superior intelligence or ability. An IQ score of 140 or higher is defined as genius. Very few people will score that as the normal range of human intelligence is 90-109.
A person can be absolutely stupid in almost every area of life, but a genius in one. For example, my sperm donor was an idiot and a fall down drunk. But if you were to give him some tools and wood, he was a genius. He could do things that most could only dream about. And he loved doing it. If he had chosen that as a career, I would have grown up privileged. There would have been a waiting list for his work. He was that much a genius with wood.
Then you also have to consider autistic people. They are not stupid, but sensitive to things. Many can do and remember things that simply amaze people who are not autistic. They are often genius, even though they may not have that 140 IQ score. The autistic range is far and wide. But it in no way means stupid.
As for me, I'm schizophrenic, bi-polar, BPD, and diagnosed as a sociopath. I'm semi-intelligent in some areas, yet ignorant in most. The muscular dystrophy has severely affected my cognitive faculties. I'm much less articulate than I used to be. I'm also much less intelligent than I used to be. When I was in 5th grade my IQ was 130. I took an IQ test a couple years ago and it was 108. I'm sure it's somewhere in the 90's at best now.
Genius to some. Idiot to others.