With Hebb theory can you answer this question?
What effect does the environment have on intellectual differences in humans?
Using the Hebb theory to examine the effect environment has on intellectual differences you want to focus on intellectual stimulation that occurs or doesn't occur in the environment. This stimulation is the key to learning/intelligence. The Hebb theory posits that the more stimulation cells get to fire, the more intellectual pathways are created. Without stimulation to fire these pathways for intelligence are ...
This uses the Hebb theory to explain how environment is critical to and shapes learning and intelligence.