While environmental factors can influence intelligence, most of your capacity for intelligence is inherited. You have certain genes that ‘predict’ your intelligence. Your environment can enhance or detract from your final achievement in the way of intelligence.
That being said, I am a believer that everyone is intelligent in some way. Multiple intelligences make sense, and it makes me sad when people put IQ as the standard. IQ tests don’t measure everything (or even most things) and can be inherently flawed by including things that may or may not be something a person would have contact with in life depending on where they are from, etc. Even those with limited IQ can have smile intelligence or love intelligence. Sometimes they love better than anyone with a higher IQ because they are not bothered by what they know or don’t know.
High IQ often comes with a host of negative issues, so who’s to say it’s such a good thing to be overly intelligent? Then there’s the ‘using your intelligence’ factor. Just because you have it doesn’t mean you use it. What about ‘street smarts’? We can’t measure this (or don’t) and yet, they are often more savvy than any brainiac!
My point is that regardless of your inherited capabilities or what happens to you along the way to stunt or expand that natural genetic heritage, this is not all you are. Don’t judge yourself or others by their intelligence. Other factors come into play in determining the value of a person and their contribution to the world, so look beyond IQ to the real value hidden in every person.