James Flynn revolutionized the study of IQ 30 years ago when his study showed that IQ increases across the world, no matter what race and nation, by three percent every decade. That finally shattered the long-held belief that white people had superior IQ than those who are colored. That discovery was called the "Flynn Effect." Fast forward to the present, Flynn wrote a book which showed that nature and nurture has nothing to do with it, but chance does.
Thirty years ago, Flynn made waves in the scientific world for discrediting the long-held belief of British and American academics that the IQ of black people are genetically lower than Asians and whites; as a result, African countries are poorer.
Flynn, on the other hand, reasoned out that IQ can change as the person gets more exposed to learning which, in turn, make his analytical abilities much sharper. He also said that the influence of a person's family to the development of his or her IQ stops at the age of 17. Although the home wields more influence in a child, its effect diminishes as the child goes to school, university, and work.
As the person gets more knowledge, it will most likely match the person's genes. He will also get naturally drawn to those environments that match his genetic potential.
That was Flynn's study on IQ between generations. However, in his book "Does Your Family Make You Smarter?," he explored the growth of IQ within generations and the result showed that IQ growth can't be solely attributed to either genes or the environment. A person becomes smarter not because of nature of nurture but because of what Flynn calls as "chance factor."
The chance factor, according to Flynn, is the person's ability to improve himself. For example, a person who has a very a high IQ decided not to study at school, go into fistfights, and be a headache to his teachers will have a higher possibility ending up in a humdrum low-paying job and less-than stimulating environment. That kind of circumstance will most likely decrease that person's IQ by 10 percent.
On the other hand, if the person decides he's fed up talking only about, let's say, football and girls and decided to pursue a degree in university. That person's IQ will more likely increase from 120 to 130.
