Do blacks and whites who grow up equally wealthy end up with the same mean IQ?

Some people argue that mean IQs for whites and blacks differ because blacks tend to come from poorer families. A black kid raised with resources equal to a white kid will have the same IQ. Is this the case? 

Using data from the General Social Survey, I calculated mean IQ for blacks, whites, and others for several ranges of father's socioeconomic index (SES): 1-2 standard deviations (sd) below average, 1 sd below average to average, average to 1 sd above average, 1-2 sds above average, and over 2 sds. The sample size is 12,016 (immigrants were excluded). Here's a graph that summarizes the results: 

Blacks and whites raised at the same SES level do not have the same mean IQs. The higher white average ranges from about 7 points among the poorest group to more than 10 points among the wealthiest group. By the way, other non-whites--mostly Hispanics--are closer to blacks than whites. 

It's a clean sweep: IQ is more predictive of education, income, and job prestige than dad's social class

 Someone at Twitter, I forget now, wondered if IQ or one's social class was more important for adult success. Well, the General Social Survey can help with this. I threw in basic demographics as controls. 

Here are OLS results for income:

Looking at the betas, you can see that IQ is more strongly predictive of income than father's socioeconomic status (PASEI). Notice how race is not statistically significant when IQ is included in the model. 

And job prestige? 

IQ is much more predictive of job prestige than father's PASEI. 

The results for education should be even stronger for IQ:

 

The beta for IQ is much larger than for dad's social class. How far one goes in school depends much more on brains than dad's wallet (or his other influences). 

Which is more important for education attainment: your IQ or your dad's social class?

While I am convinced that genes are a strong influence over people's lives and that the impact of the parenting is wildly exaggerated, I am open to data on these questions--I call myself Inductivist after all.

This meta-analysis of 15 heritability studies conducted in a variety of countries and decades found that shared environment explained a sizable portion of the variation in educational attainment; to be specific, almost 40%. That's a much higher average than typically seen in heritability studies.  The authors also found that shared environment was stronger for women and for people studied prior to 1950, suggesting that factors like family financial support have mattered more for women and for people in the past.

We can use General Social Survey data to answer a related question: Is educational attainment due to IQ or dad's socioeconomic status (SES)?  First, let's see how strongly each predicts years of education completed (I limited the analysis to data from 2010-2018, sample size = 947):

Standardized OLS regression coefficients

Model with Father's SES only
Father's SES  .37***

Model with Child's IQ only
Child's IQ   .45***

IQ is the stronger of the two predictors, but nurturists might argue that father's SES causes child's IQ which, in turn, determines educational attainment. We can address this question by entering both into the model as predictors. By doing so, we can see if the link between IQ and education shrinks to nothing once we've accounted for the influence of dad's SES.

Model with Father's SES and Child's IQ
Father's SES   .24***
Child's IQ  .44***

When both predictors are entered into the same equation, the father's SES/child education correlation is reduced, but the impact of IQ on schooling is basically unaffected. We can interpret these findings this way: How far you go in school is influenced by your dad's social class (consistent with the meta-analysis), but your own IQ is much more important. The strong correlation between IQ and schooling is not at all due to the tendency of high-status men to both have smart kids and to help them continue in school.

By contrast, part of the reason why father's SES is linked to child's educational level is because high status men have smart kids, and smart people naturally go further educationally. Once you take into account the pathway from dad's status through offspring IQ to completed education, the link between dad's class and child's educational attainment is weakened substantially. In other words, factors beyond the kid's IQ, like family financial support, are not as strong important as they look.

I looked at females only and got the standardized coefficients of .23 (dad's SES) and .43 (child's IQ), so the process works the same for girls as well as boys.

I also looked at mom's SES, and I found very similar results.

***p < .001, two-tailed test

UPDATE: The strong correlation between IQ and years of education reminds me of Taleb's anti-IQ argument: IQ-type tests get you into college, so there is a built-in correlation. There might be a link between test score and which college you get into, but there is no such circularity with how many years of school you complete. Regardless of your test score, you can get admitted to some college.

Is IQ just a measure of social class?

A common claim by IQ skeptics is that the test simply measures social class.  If an IQ score is simply a proxy of social status, then the two variables should be very highly correlated. The statisticians tell us that a good proxy should correlate with the original variable at no less than 0.8. 

An excellent example of a worthless proxy that is used all the time in social science research is opposition to racial preferences. It is used for whites as a proxy of racism.  The correlation between opposing preferences and feeling cool toward blacks is a whopping 0.1--a trivial relationship.

So what's the correlation between your class and IQ score?  I'll be generous to the skeptics and choose the measure of social class that correlates most strongly with intelligence; namely, father's educational level. Using the General Social Survey (GSS), I exclude immigrants since they are likely to have a disadvantage on the test (which is an English vocabulary quiz).  Here is a visual of the relationship (sample size = 20,533):

Sure, IQ rises with dad's highest degree earned, but the connection is not strong. To be specific, the correlation is only .27.

This is a typical problem for sociological explanations. In this instance, the privilege of one's class is supposed to determine one IQ's score. The mechanism should work in lockstep fashion with few exceptions, so the correlation should be almost perfect.  But in sociological research, most observed correlations are weak.  The world is much messier than the sociologist predicts.

The geneticist does not face this problem. Since each sibling is genetically unique (and there is also developmental noise), he expects lots of IQ diversity within a family. And that's exactly what we get: two randomly selected full siblings are expected to differ in IQ by 12 points. That's a lot. 

The sociologist predicts siblings (at least same-sex siblings) will have the same IQs. That's way off.  Since parents and offspring differ genetically, the geneticist predicts only a modest link between social class and IQ, and that is exactly what we get.

Again, biology trumps sociology.

Data: Which explains American social mobility better? Sociology or biology?

I remember the first department party I attended as a PhD student in sociology.  I joined a conversation between a young faculty member who specialized in social mobility and a professor who was an international expert on urban sociology. I was stunned when the older guy said to the young guy, "Why do you study American social mobility? There is no such thing."

I had a bigger mouth then, and said, "Could've fooled me. My parents never stepped foot on a college campus. I have one brother working on his JD and another has a BS in business and will probably make double what I end up making." (Turned out to be more like three times as much.) He said something about exceptions and moved on to something else.

So the sociological view is that kids inherit the social class of their fathers because the system is rigged that way. The logic of this theory is that there should really be few exceptions. The genetic view, on the other hand, is that since children get their genes from parents, they will tend to end up where their parents are, but since each child gets a unique combination of genes, and since each child is exposed to unique developmental events, offspring will often depart from the class of their parents by either moving up or moving down. The pure sociological view has no explanation for these departures. An open, fluid, meritocratic America is a fiction, according to these people.

What does the General Social Survey say?  You can see below a contingency table of father's and offspring's highest degree earned (sample size = 1,325, ages 30-39, years 2010-16). (I use education because we have data for both generations):

 

As both theories predict, there is a tendency to end up where the old man did, but there are PLENTY of exceptions. 

Adding up all the cells where the kids went further in school than dad, we get 35% of the total. If we do the same for all offspring that fell short of their father's education, we get 15% of all respondents. Yet we're told you're never supposed to be able to fall in American society where privilege reigns. 

Intergenerational stasis happens to just 50%. This pattern is consistent with a genetic/developmental theory of outcomes. It does not support the opinion of my America-hating professor.

What causes a person to climb the ladder of success?

Here's the abstract from a new genome-wide association study on social mobility. Sounds about right to me: 

A summary genetic measure, called a “polygenic score,” derived from a genome-wide association study (GWAS) of education can modestly predict a person’s educational and economic success. This prediction could signal a biological mechanism: Education-linked genetics could encode characteristics that help people get ahead in life. Alternatively, prediction could reflect social history: People from well-off families might stay well-off for social reasons, and these families might also look alike genetically. 

A key test to distinguish biological mechanism from social history is if people with higher education polygenic scores tend to climb the social ladder beyond their parents’ position. Upward mobility would indicate education-linked genetics encodes characteristics that foster success.  

We tested if education-linked polygenic scores predicted social mobility in >20,000 individuals in five longitudinal studies in the United States, Britain, and New Zealand. Participants with higher polygenic scores achieved more education and career success and accumulated more wealth. However, they also tended to come from better-off families.  

In the key test, participants with higher polygenic scores tended to be upwardly mobile compared with their parents. Moreover, in sibling-difference analysis, the sibling with the higher polygenic score was more upwardly mobile.  

Thus, education GWAS discoveries are not mere correlates of privilege; they influence social mobility within a life. Additional analyses revealed that a mother’s polygenic score predicted her child’s attainment over and above the child’s own polygenic score, suggesting parents’ genetics can also affect their children’s attainment through environmental pathways. Education GWAS discoveries affect socioeconomic attainment through influence on individuals’ family-of-origin environments and their social mobility.

Elites vote Democrat, not Republican

I'm tired of the old Democrat myth that the Republican Party is the party of elites. Looking at General Social Survey data, it's not surprising to see that only 24% of high school dropouts voted for Romney in 2012, but how many people with advanced degrees voted for him? A whopping 32%. Most highly successful people vote Democrat because their competitors aren't the poor. Their enemies are America's Middle. They seek an alliance with the poor so they have the numbers to subjugate ordinary Americans.

Father's social class and homosexuality

Using GSS data, I calculated the mean father's socioeconomic index for women who are straight, bisexual, and lesbian (sample size = 8,551).


Mean Father's Socioeconomic Index

Straight 47.3
Bisexual 50.4
Lesbian 52.7*

*significantly higher than straight women


Compared to straight women, lesbians come from significantly higher status families. And for men (sample size = 7,867):


Mean Father's Socioeconomic Index

Straight 48.2
Bisexual 50.1
Gay 49.3

Gay men do not come from significantly higher status homes than straight men.

I'm not sure how to explain the pattern. Women from higher class homes might be more willing to admit lesbianism or might be more willing to adopt a lesbian orientation. There is evidence that lesbianism is more environmentally influenced than homosexuality. One might suggest that higher status fathers are more masculine (at least in some ways) and more likely to have masculine daughters.

IQ is more important than social class

This is a structural equation model of a cohort of Swedish men. It shows that IQ is an important determinant of income and especially occupational position.  Much of its influence is indirect: it is a strong predictor of educational level which, in turn, is a powerful determinant of both income and especially occupational position. Parent's social class, by contrast, is comparatively less important. It has little to no direct influence on income or job position, and predicts educational level only moderately.

A whole academic field--sociology--developed on the view that social class is of critical importance. If disciplines emerged as a result of empirical support, students could major in IQiology.

Why do wealthy white conservative women have more children?

In the recent post on the fertility of wealthy white women, a reader raised the question of why conservative women have more children. He suggested it was greater religiosity and less involvement in the workplace.

We can use OLS regression analysis to help answer the question. I included white women ages 40-59 in households earning at least $100k in 1986 dollars. First, I regressed the number of offspring onto political orientation. The unstandardized coefficient is .161 (p < .05) which indicates that conservative women have significantly more babies. If we include church attendance, the coefficient drops to .120. If, instead, we include hours worked last week, the political coefficent drops to .132. If, instead, we include years of schooling completed, the political slope falls to .131. (The correlation between education and conservatism among wealthy white women is -.16--liberals tend to be more educated.) If all three controls are included in the model, the results look like this:


Number of offspring (sample size = 231)

Conservatism .081
Church attendance .098*
Hours of work -.007
Education -.081*

*p < .05, two-tail


With the three controls included, the link between poltical views and number of offspring falls to non-significance. In this full model, number of hours worked also has no significant effect on fertility.  To put it in plain English, the data indicate that wealthy white conservative women have more children because they are more religious and less educated than liberal women.

One caution: education's effect is not the influence of IQ. Among this demographic, IQ is unrelated to fertility. The correlation between IQ and number of kids is .02--basically zero. Education's influence appears to be cultural.

Social class, camping, and fundamentalism

Do lower status whites enjoy nature? GSS respondents were asked if they've gone camping in the past year. Based on occupational prestige scores, I constructed 4 classes: lower, working, middle, and upper.

Percent who camp

Lower 41.6 (n = 269)
Working 46.5 (n = 376)
Middle 46.6 (n = 397)
Upper 53.3 (n = 260)

The share goes up a little among higher classes, but the differences are not statistically significant. Enjoying nature is common at all social levels.

While we're focusing on class, let's look at the belief among whites that the Bible is inerrant. In an earlier post, I looked at differences by education, but occupational prestige is a more direct measure of social class. I'm highly educated but far from upper class.


Percent who believe Bible is inerrant

Lower 37.8 (n = 1,345)
Working 34.0 (n = 1,725)
Middle 25.1 (n = 1,318)
Upper 17.9 (n = 751)

The lower and working classes are not significantly different, but all other comparisons are. The claim that Biblical fundamentalism is an middle- or upper-class movement is simply incorrect.

Social class and fundamentalism

A reader commented in the "Fundamentalists and delinquency" post that belief in the inerrancy of the Bible is an upper-class phenomenon.

GSS participants were asked: "Which of these statements comes closest to describing your feelings about the Bible? 1. The Bible is the actual word of God and is to be taken literally, word for word. 2. The Bible is the inspired word of God but not everything in it should be taken literally, word for word. 3. The Bible is an ancient book of fables, legends, history, and moral precepts recorded by men."

Here are mean levels of education by answer for whites (sample size = 19,324):

Word of God 12.01
Inspired word 13.71
Book of fables 14.33
Other 14.13

At the 95 percent confidence level, the Inspired Word group is significantly more educated than the Word of God group, and the Book of Fables group is more educated than both of them.

IQ, SES, and incarceration

This graph is taken from a new study of more than 11,000 people. You can see that, while increasing SES  lowers the risk of incarceration only a little bit, increasing IQ lowers the risk sharply.

So much for the liberal claim that social class is everything.  

Parental income and IQ among teens

Here's a new study of a large sample of teens published in Personality and Individual Differences that shows that the IQs of children from wealthy homes are higher, not because of money, but because of their parents' superior genes.

Parental educational level and family income have been related to individual differences in intelligence. However, large and representative samples are hardly available. Here two samples of young and old adolescents totaling 3233 boys and girls completed an intelligence battery comprising abstract, numerical, verbal, mechanical, and spatial reasoning subtests. Parents’ educational levels, family incomes, and adolescents’ general intelligence (g) were simultaneously related using SEM (structural equation modeling) analyses. The main findings show that (1) parental education strongly predicts family differences in income, (2) family income is not related to adolescents’ intelligence, and (3) parents’ education predicts adolescents’ intelligence regardless of family income. Because it is widely acknowledged that personal intelligence is the best predictor of educational differences, the next causal chain is endorsed: brighter parents reach higher levels of education, which allows approaching better occupations, and, therefore, they can create families with higher incomes. Adolescents from more affluent families tend to be brighter because their parents are brighter, not because they enjoy better family environments.

Social class and autism

From a new study on the increasing prevalence of autism:

The prevalence of autism has increased precipitously—roughly 10-fold in the past 40 years—yet no one knows exactly what caused this dramatic rise. Using a large and representative dataset that spans the California birth cohorts from 1992 through 2000, we examine individual and community resources associated with the likelihood of an autism diagnosis over time. This allows us to identify key social factors that have contributed to increased autism prevalence. While individual-level factors, such as birth weight and parental education, have had a fairly constant effect on likelihood of diagnosis over time, we find that community-
level resources drive increased prevalence.

The researchers conclude that the epidemic is the result of a greater probability of being diagnosed, and that until recently, diagnosis depended heavily on having money and living in better-off communities where the focus on autism began. Social class factors have been more important for less severe cases of autism where diagnosis was less obvious. 

Other factors that are associated with a greater risk: higher parental education, low birth weight, being male (of course), being first-born, having older parents, and not being on Medi-Cal.

I find it odd that race and ethnicity were not examined. It's a California sample, you're focusing on social class, and you don't control for race and Hispanicity? Maybe it doesn't matter, but they don't seem to address it. Being on Medi-Cal matters, and it is correlated with NAMishness. And of course there is no mention of the possibility that social class might be associated with genes implicated in autism. Everyone just knows that social class has nothing whatsoever to do with genes. It's the same old story that class reflects privilege and access and nothing more.

Gallup: Little evidence of an American desire to soak the rich

Here's a new Gallup poll on attitudes toward extending tax cuts to all Americans (and unemployment benefits). Where's the evidence that ordinary Americans are itching to stick it to the rich?  Sixty-six percent of all Americans wants the tax cuts extended for all Americans; a majority (52 percent) of Democrats favor the extension.

The country is split (44% vs. 40%) when respondents are given explicitly the choice to raise taxes on the wealthy. Obama is wrong to claim that the people are on the Dems' side on this issue. Based on my analysis of GSS data, many of those who favor it are black and Hispanic.  

Do NAMs want to tax the rich because they're poor or because they're NAMs?

Predictors of wanting to tax the rich, N = 4,743.
Predictors	b	b	b
Black	.87	.59	.57
Hispanic	.65	.46	.38
Income	--	-1.08	-.99
Liberalism	--	--	.32

Compared to whites, non-Asian minorities (NAMs) are more likely to favor the government reducing income inequality by taxing the wealthy. Is this because they are poor and liberal, or because they are NAMs?

The table displays unstandardized OLS coefficients. The first model includes only two predictors: whether or not the respondent is black and whether or not the respondent is Hispanic.  Both groups are significantly more likely than whites and Asians (the reference group) to favor taxing the rich. In the second equation, income is added. Not surprisingly, higher-income people are less likely to favor being taxed to reduce inequality. This is the same finding reported in the last post. The coefficients indicate that the influence of income reduces the effect of race, but even with the adjustment, blacks and Hispanics are significantly more likely to favor income equalization. And you can see that even when the extent of one's liberalism is added to the model, the racial gap persists, just in a reduced form.

In other words, blacks and Hispanics want to tax the rich: 1) because they are poor; 2) because they are liberal; and 3) because they are minorities. Each of the variables has an independent effect, but of course, income and liberalism may just be mediating the relationship between race and taxes. It is not unreasonable to conclude that NAMs are poor and liberal because they are NAMs.

But even if we partial out the effects of income and politics to see what is left of race, income and liberalism reduce the racial effect by less than half (just compare coefficients across the models). The pattern of results is consistent with the view that NAMs want high taxes for the wealthy because they perceive them as privileged and white, and this feeling goes beyond simply being poor and liberal .     

The GSS speaks on taxing the rich

TGGP was so right in the last post to ask, "Where's the data?"

GSS respondents were asked the following question: "Some people think that the income differences between the rich and the poor ought to be reduced, perhaps by raising the taxes of wealthy families or by giving income assistance to the poor. Others think that the government should not concern itself with reducing this income difference between the rich and the poor. Here is a card with a scale from 1 to 7. Think of a score of 1 as meaning that the government ought to reduce the income differences between rich and poor, and a score of 7 meaning that the government should not concern itself with reducing income differences. What score between 1 and 7 comes closest to the way you feel?" 

Unfortunately, the question is double-barrelled, asking about taxing the rich and helping the poor, but if anything, the wording should tilt responses toward government intervention.

I divided the sample of whites from surveys from the past decade into three equally sized groups: low-income, middle-income, and high income. The mean responses to the question look like this:

Mean score

Low-income 3.66
Middle-income 3.72
High-income 4.28

The low- and middle-income groups are significantly more in favor of equalizing, but the differences are fairly small (Cohen's d for the low/high comparison is .32).

Plus, the typical response for the poorest group is close to 4, which is the neutral answer. Even poor whites are pretty indifferent about reducing inequality. I don't see stick-it-to-the-rich sentiment here.    

Elite liberals don't get us

These elite liberals are completely mystified about why ordinary Americans don't want to tax the rich aggressively. These supposedly creative people even lack the imagination to come up with a good answer. So as the son of a retired maintenance man, let me help them out. The problem is that they assume that we rubes are naturally good at hating, so how in the world could we not want to stick it to the people who clearly deserve our hostility? They make the mistake of believing that we think like them.

The reality is that ordinary American assume that they are just as good as rich people; they are just people like ourselves. They are not cardboard monsters like liberals want us to believe. They are just folks. And just like we don't want blacks or Hispanics or Jews or regular white guys to get hosed, we don't want anyone to get hosed. If I don't get angry that some rich guy pays the same for a lawnmower at Sears as I do, why am I going to get worked up if he doesn't pay taxes at a higher rate?  He's paying much more into the system than I am as it is. If the government is giving him sweet deals that I don't get, then that should be stopped. But why squeeze more out of him?

I see soaking the rich as a little like gang robbery. We take his money because we've got the numbers to get away with it. And then liberals make us feel righteous about our crime. "Social justice" sounds so noble, doesn't it? We don't want to bleed the guy because we're not criminals. If he stole the money, then he needs to rot in prison.  But we don't believe capitalism is organized theft. If he didn't break any laws to get it, then I'm the thief if I join the mob to strip him of his cash.

Antisocial behavior more heritable for girls and the wealthy

According to this Swedish twin study, heritability for teenage antisocial behavior is higher for females and people from high-income homes. This pattern indicates that environments are more uniformly prosocial for girls and wealthy kids, so the impact of genes becomes more powerful. By contrast, men and poor people inhabit more diverse environments which can either encourage or discourage bad behavior, so genes end up comparatively less important.

These findings are consistent with a claim made by Emile Durkheim a century ago that social conditions make or break men more than women.