Is intelligence hereditary or acquired?
Twin research has shown that 55% of intelligence is determined by genetics. This genetic component determines the upper limit of your intelligence, that is the maximum intelligence you can realize. Your environment determines whether you will actually reach this maximum level. You could compare intelligence with athleticism. Some people are more inclined to sports than others.
Environmental factors of intelligence development
Environmental factors, such as the the way your parents raise you, the culture you were born into, education, and your circle of friends, determine 45% of your intelligence. Such environmental factors are especially important in your youth.
If you are raised on a poor diet and in an environment that does not really appreciate education, you will become less intelligent than if you are raised on a healthy diet and encouraged to perform well in school.