how comes some peolple are dumber than other people and other people are even clevere?

Question: how comes some peolple are dumber than other people and other people are even clevere?
- Keywords:
  clever,
  education,
  people
Asked by to Claire, Sergey on 27 Jun 2014. This question was also asked by .
- Claire Shooter answered on 27 Jun 2014:
  
  Who you define as ‘dumb’ is usually personal to you and what you consider to be ‘smart’. Most people are pretty equally intelligent, just in their own way. It’s usually your loss to consider anyone to be dumb. Because there isn’t any universal definition of the term ‘dumb’ this is quite a hard question to answer. I would say that people who are less intelligent may be so in part because of nature: their genetics, and events that happened to them before birth that affect their brain development, and in part because of nurture: the events in their life that have shaped both what they learn, and their ability to learn it and apply it.
- Sergey Lamzin answered on 27 Jun 2014:
  
  It has to do with laziness. Some people are just lazy, thus they don’t study as hard and appear ‘dumber’.
  
  But everyone is born with the same abilities, you have the potential to be either dumb or clever. It’s what you make of it. Study hard and you will be clever. Your fate is not predetermined!

Question: how comes some peolple are dumber than other people and other people are even clevere?