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I’ve read numberless op-eds in recent years lamenting conservative distrust of scientific experts. Yet, progressives are remarkably anti-expert when it comes to the venerable field of research into human intelligence.

IQ psychometrics emerged as a scientific field of study in the first decade of the 20th century when Charles Spearman invented factor analysis, which led to him proposing the existence of a general factor of intelligence in 1904. And then, the next year, Alfred Binet invented the first IQ test.

By the end of the 1930s, the modern IQ test had largely matured. Over the past eighty years, IQ has proved itself to be the single most useful and reliable metric in psychology.

In the liberal 1960s and 1970s, IQ science was rigorously interrogated, especially over the racial gaps in average IQ, but emerged battle-tested and resilient.

“How much money will your parents provide to help you buy a home in a good school district?”

That doesn’t mean that IQ is the be-all and end-all of the human sciences. Human beings are incredibly complicated. But it does mean that over the past 120 years, IQ research has proved its value again and again.

There are multiple reasons why liberals are such science deniers when it comes to IQ, but don’t overlook sheer ignorance. IQ is a complex subject. I’ve always found writing intelligently about intelligence to be cognitively demanding. The subject is out at about the boundary of my intellectual limits.

So, it’s much easier for progressives to sneer at the purported motivations of people who aren’t ignorant about IQ than it is to learn the science.

Thirty years after The Bell Curve, it’s worth looking into a new book summarizing the state of the art in IQ research, IQ: From Causes to Consequences by Monegasque science journalist Philippe Gouillou.

This short book covers a huge number of studies touching on IQ.

As Charles Murray explained in a 2004 interview with Gouillou:

Philippe Gouillou: Do you think IQ could be insightful in research on other topics? Which ones?

Charles Murray: The better question is what social and economic phenomena can be fully understood without examining the role of IQ? Offhand, I cannot think of any.

Most of the studies highlighted in this new book are from the 2020s, including one that I initially assumed was an April Fool’s Day 2024 hoax but appears to be real: “Penile Length and Intelligence Quotient: A Cross-Sectional Analysis in 139 Countries” by Wang and WangDing.

For example, Gouillou reports that higher IQs correlate with a stronger ability to “decouple” facts from emotion. I run into this all the time when people get mad at me for pointing out that, say, IQ is important. They wish IQ weren’t important for personal reasons, so they feel strongly that I must be a bad person for saying something they would prefer to be false. The way I look at it, however, is that even if I were a horrible human being, IQ would still be important.

In Aporia this month, Noah Carl reviews some recent papers in IQ research:

IQ isn’t everything but it’s a lot

Jun 13, 2025

…First let’s compare the effect of IQ to that of social background….

In a 2022 paper, Marks analysed data from two large, longitudinal surveys of Americans. His outcome measures included school grades, test scores, occupational attainment, income and wealth. On practically every outcome measure, the effect of cognitive ability was “far more powerful” than that of social background. And the effect of social background declined “substantially” when controlling for cognitive ability—but the reverse was not true….

But now, I want to turn around and suggest a way in which IQ has probably declined in importance relative to family background in recent generations. I think that the importance of upbringing, the essence of “nurture,” for adult life has grown in one specific way since these Nature vs. Nurture debates really got rolling in the American social sciences in the 1960s: Namely, how much money will your parents provide to help you buy a home in a good school district? I’m not sure that social sciences have come up with a good way to measure that yet.

During the egalitarian high point after World War II, inheritance wasn’t as big of a deal as it had been in the 19th century or as it is becoming again in the 21st century. Baby boomers typically had to split their inheritances with multiple siblings, and until the late 20th century, the dollar value of parents’ wealth in stocks and homeownership usually wasn’t much. (Instead, a lifetime pension was then a prized possession, but it’s hard for your kids to get their hands on it.)

Back then, you never heard about “generational wealth.”

The range of wealth was much more compressed a half century ago. For instance, I can recall feeling that the single most boring entry in the otherwise thrilling 1969 Guinness Book of World Records was “Richest Man in the World”: J. Paul Getty was worth about a billion bucks, but that was relatively much less than Rockefeller or Ford had been worth in 1929. Similarly, the chairman of General Motors was paid an annual salary of one…million…dollars. But Charlie Chaplin was making that kind of money in the early 1920s when the dollar went a lot further. And when I was 10, earning a million dollars per year by being Charlie Chaplin sounded like more fun than being GM’s chairman.

On the other hand, the future didn’t seem that financially stressful, either. The San Fernando Valley was a nice place to live, but much of it was still farmland, so home prices remained reasonable.

I went to a Catholic school that charged a modest tuition because nuns weren’t expensive. Yet, the free Los Angeles Unified School District schools were good enough that the great majority of the Jewish kids I knew from the baseball league at the park went to public schools. (They tended to think Catholic schools were slightly un-American.)

San Fernando Valley public schools remained heavily Jewish until the end of the 1970s when two-way busing for integration was imposed for a few years. Young Ice Cube of N.W.A was bused straight outta Compton to Taft High School on tony Ventura Boulevard in Woodland Hills (where he flourished), and various young Shapiros and Cohens were bused to Compton (where they did not), until their parents could buy houses in Calabasas in the Los Virgenes school district.

And, when the Jews left, well, that was about it for the Los Angeles Unified School District.

Higher education wasn’t economically daunting, either. A few years ago, I was talking to my Jewish dentist, who is my age and who grew up near me in the Valley, about where he went to school. I’d estimate that his parents didn’t pay more than $2,000 in tuition or fees for him all the way through UCLA dental school.

My cousins grew up similarly in Arcadia, Calif., a pleasant but seemingly rather run-of-the-mill suburb in the smoggy flatlands of the San Gabriel Valley east of Pasadena, going to the local public schools. Then, for reasons that remain obscure to us round-eyes, Chinese millionaires picked out the Arcadia school district to become their Utopia of the Tiger Mothers. From Wikipedia:

The city had remained 99% white until the late 1970s, but in 1985, the ‘Los Angeles Times’ reported that the Asian population had grown from 4% in 1980 to an estimated 9%, overtaking Latinos, who accounted for roughly 7% of the population. By the 2020 census, Asians consisted of 64.56% of the population…. In 2016, Arcadia was ranked the fifth most expensive housing market in the United States by ‘Business Insider,’ with an average listing price of $1,748,680 for a four-bedroom home.

Other than the smog, the San Fernando and San Gabriel Valleys were pretty great places to be a kid in 1970. For instance, I grew up 2.4 miles from that weird A-frame house whose exteriors were featured on The Brady Bunch.

Built in 1959, it was a three-bedroom, 2,477-square-foot house on a 0.29-acre lot: lavish by the standards of the Los Angeles suburbs, but not by, say, suburban Kansas City norms.

By 2018, it sold for $3.5 million.

Granted, some of that high price was due to nostalgia, but still…

In summary, for the postwar generation or two, Nature mattered a lot. But lately, Nurture has made a comeback in importance. Namely, how much money do your parents have? How self-sacrificing are they? And how many of your siblings do they also have to subsidize?