IQ is the capacity to grasp concepts or abstractions. Somewhere between fifty to eighty percent of a person’s intellectual ability is genetic, with the effect increasing with age. Schooling (education) increases knowledge, but it has only a small effect on IQ.
The SAT is a good measure of intellectual ability. The math and verbal sections of the SATs are valid predictors of performance for everyone. People who score highest do the best academically, i.e., the higher the score on the average, the better their grades. The same is true at work; the more complex the job, the more IQ helps performance.
IQ is also a significant predictor of many positive life outcomes, e.g., job success, income, health, longevity, marital success, and law abidingness. Presumably, this is because higher IQ enables people to process more information and make more informed decisions.
Though training on the SAT test can be of some help, the effects, based on evidence from the best-designed studies I have read about, are relatively modest.
Some say that it is unfair that some people have higher IQs than other people, but it is not unfair. It is simply a fact. Fairness is a human concept that does not apply to the metaphysically given—in this case, your genes. Beyond IQ, genetic differences have effects across the board, e.g., some people are naturally better athletes than others and less vulnerable to certain diseases (as noted in Assertion 15).
That said, IQ should not be confused with actual learning or the acquisition of knowledge. As noted, IQ refers to capacity or potential. People with higher IQs can learn faster and are more able to grasp higher-level abstractions. Not everyone can grasp nuclear physics. But ability does not equal learning, nor does it mean that every person with ability will work hard to acquire knowledge. Some people put in more volitional effort to learn than others. In sum, everyone can increase their knowledge and skill to some extent through thinking, effort, and practice, but everyone does not get to the same place.
In 2008, journalist and author Malcolm Gladwell claimed in his book Outliers that anyone can become a world-class violinist with 10,000 hours of practice. This claim was based on the research and claims of Dr. Anders Ericsson. Some years ago, a colleague and I tried to get the raw data that allegedly proved Ericsson’s claim. The data had disappeared from a computer in Germany. No one knows how.
This is not to accuse anyone of scientific misconduct. But a properly designed study would have picked people at random for training rather than just looking at people who were already violinists. One can be virtually certain that 99.999 percent of any genuinely random sample would not make it to the world-class level no matter how hard they worked. Effort has limits. Every teacher knows this.
Other factors that could affect practical success besides IQ, natural skill, and effort include luck (see Assertion 23), passion for one’s career, quality of training or coaching, mental and physical health, and rationality.
What is the role of family? Family may have a role in IQ because of genetics: higher IQ children are usually born of parents with higher IQs. Parents can also be role models for education and achievement. I believe that the most important role of the family in rearing children who are successful in life is psychological.
Mean, cold, cruel, irrational, criminal parents can do tremendous harm to their children, regardless of IQ. A mistreated, abused child may suffer physical damage, including brain damage, as well as psychological damage. Children from abusive and neglectful parents can automatize many wrong subconscious conclusions about people, the world, and themselves long before they are able to understand what is going on conceptually. This may require extensive psychotherapy and medication later in life.
Children of “mixed” parents, meaning they have some virtues and some flaws, can survive and thrive if the children later use their own independent judgment to decide what to agree with and what to reject. Therapy may be of benefit or be needed by some here, too.
Of course, “perfect” parents are rare, but warmth combined with teaching healthy values including moral principles and using rational discipline will give the child a good head start, regardless of IQ.