Edited

I think culture plays a tremendous part in it, especially mind controlled cultures.

Questions have been raised because most african americans do not do well on the SAT exams for college, some complain that it is geared or rigged for white people.
There is a way around taking SAT exams, by attending junior colleges for a few credits. These colege credits are enough to qualify you for any major college without an entrance exam. This system is used by whites as well as blacks.
I do not know what if any effect race may have on intelligence, but I have seen many educated blacks and arabs with the mindset of, "it's us against the whites" or "us against the infidels", which goes against any thought of unity of the races among us. Mrs. Obama has been overt about it in many instances along with the church she attends. Whether it is overt or covert, it is still an animosity that breeds hate and does not move beyond the "us against them" mentality or help unify the races and move forward as one nation where all are equal and prosper together.

Japan was rather primitive before the war. That all changed when American gave the japanese the power and freedom to govern themselves through a democracy they never had before, plus a mandatory educational system for children.

I think there is too much corruption and power over people in africa, south america and a few other countries, where a select few do not want the people to be educated enough to question and think for themselves.

Ignorance, hunger, fear and hoplesness breeds superstion and weakness that exposes people to the control of the few with corrupt power. Those in power prey on their weakness, and will fight any change that may threaten their power and wealth for their heirs to take over.

Look at the mind control of north korea and starved people, while the government and military live well. The people are no longer individuals, they are a controlled hive that worship those that control them and dare not question.

China is no far off from that left over mentality of maoism, with government control and enforcement of what people should read, see and hear. There are still many villages of primitive conditions where all fear the government official and his power in their villages.

Look at the cultures in india and the islamic parts of india, all you need to do is look at the caste system of control over humans.

Look at thee islamic states with power in the hands of a religious sect that dictates what to think and how to live, and you better fesr their authority.