While intelligence does have a genetic component, I think environment is the largest factor. If a individual is in survival mode and constantly bombarded by negative things and or violence then there is no room to explore, expand, and build on things that academia considers as intelligence, intelligent traits,  or what they test for to prove intelligence. A bad environment and social problems people face will hinder intelligence. However, surviving in that kind of environment requires it’s own kind of intelligence. There are so many kinds of intelligence. Guilford suggested that intelligence is composed of more than 150 separate factors (p 196). If a person is free of conflict and nurtured in their ability to achieve greatness and learn they will meet the bar that is set before them. They will grow if they have the peace and time to read and learn and most importantly to think. New ideas and perspectives will take root if they are exposed to them. Environment is everything.