Heritable and heritable: the gifted and the lucky

By Razib Khan | November 21, 2011 1:06 am

A few days ago Kevin Drum put up a post with the title “Being Poor in America Really Sucks”. He linked to a Pew survey which reported that the United states seems to have a stronger correlation between parent-child socioeconomic outcomes than most other nations. The implication here is that social mobility in the United States is lower than in other nations, in contradiction to our national mythology. This seems generally correct, in that I’ve seen this result reported repeatedly for the past decade (I’m sure you could slice and dice the finding to show it wasn’t quite right, but to a first order approximation you’d still have to start with that result before deconstructing it). But the finding itself is not what caught my attention. Drum goes on to say:

But in the United States they do a lot worse. The Pew chart is normalized so that children of middle-educated parents score in the 50th percentile and other children are compared to that standard. In Canada, the least-advantaged kids manage to score at the 37th percentile. In the United States they score at only the 27th percentile.

Now, it’s pretty unlikely that Canadian kids with low-educated parents are genetically unluckier than American kids with low-educated parents. Genes may account for some of the overall difference between rich and poor kids, but not for the difference between Canada and the U.S. That has a lot more to do with how we raise our kids and what kind of attention we give them at early ages. On that score, the United States does wretchedly. We simply don’t give our poorest kids a fair start in life.


What I want to explore is the general issue of the correlation between the trait of a parent and the trait of a child. This correlation can be driven by a variety of factors. It could be heritable in the technical sense, in that the correlation across the population of the trait between parent and offspring is due to variation in genes. Or, it could be heritable in the colloquial sense, where parents provide their offspring cultural and social capital. Heritability in the latter sense is probably what Drum and most people think of when they see a tight correlation between parents and offspring.

Nevertheless, we need to consider the other option. Education and academic test scores are different traits, but they are roughly reflective of the same underlying characteristic, academic aptitude. If you consider them the same trait then you can think of the chart above as a parent-child comparison. In a classic quantitative genetic model the correlation is going to be low when “environmental noise” dominates the system, and the correlation will go up as environmental noise disappears. In other words, the correlation will increase in a perfect meritocracy, and social mobility will decrease!

I don’t necessarily think that this explains the situation above. In fact, I am moderately skeptical that it’s a good explanation for the pattern above, and am willing to concede the plausibility of Drum’s thesis. My only issue is that we shouldn’t neglect the possibility that at some point in the near future we might actually attain a state where social mobility starts to decrease simply because of the genetic sorting of classes by merit. In the case of something like income and academics the role of chance is high enough that this might not seem feasible. But consider the possibility of socialized medicine, and advances in technology. In the near future we may start to see in the societies with the highest median level of medical care that life spans of parents and offspring exhibit the tightest correlations. Why? Because these are the societies were environmental variables have been removed to the greatest extent. At this point the media might begin to report about the “life expectancy gap” between the long-lived lineages and the short-lived ones, but at least in this case biomedical science could marshal persuasive evidence that the difference is due to differences in genes.

CATEGORIZED UNDER: Behavior Genetics
MORE ABOUT: Behavior Genetics
  • ThomasT

    What really baffles me is that this is something that can still surprise people. “The Bell Curve” and “The Blank Slate” were both hugely sucessful, their respective author’s are palatable at least to either left or right, they made exactly this point and when the two books were published the idea wasn’t new to begin with. Furthermore, while it does probably undermine some specific policies, it doesn’t really spell a death knell for any general political ideology so you’d think this should’ve been incorporated into the official reality a long time ago.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    #1, just like equilibrium models in economics have limited utility, so equilibrium models in pop gen/evolution/quant gen probably also do too. therefore, i’m not saying this is what is happening in the USA, but we should consider it. but i don’t presume to argue that this should be our null.

  • http://lyingeyes.blogspot.com ziel

    One obvious counterpoint to the highlighted passage is that American children of low-educated parents are indeed genetically ‘unluckier’ than their Canadian counterparts in that they are disproportionately members of what the Canadians call “visible minorities”. For that reason alone we should expect substantially reduced levels of inter-marriage in the U.S. by cognitive ability than in Canada.

    Also, for the same reason, regression to the mean will have a lower effect in the U.S. than in Canada.

    And Canada has higher levels of Asians than in the U.S., and in the U.S. Asians tend to be upwardly mobile so assuming that’s the case in Canada that would also have an effect.

    These effects are probably modest and might not explain the entire gap Drum is pointing to, but they probably add up to explain some of it at least.

  • http://blogs.discovermagazine.com/gnxp Razib Khan

    #3, makes me wonder about state-by-state breakdowns of such statistics….

  • ThomasT

    @ ziel: Sounds plausible and is pretty much in line with the point Tino from “Super-Economy” made a year ago about the PISA scores. With the much more diverse makeup of the population the US had a rather bad score on average, but once he controlled for ethnicity the US did very well. I guess if you did the same here, the spread wouldn’t be quite as high either.

  • http://www.parhasard.net/ Aidan Kehoe

    … what the Canadians call “visible minorities”

    Small terminological point; in Canada, the East Asians and indeed South Asians are visible minorities, and I’m sure they weren’t who you meant by the term.

  • Darkseid

    i think the autism clusters near silicon valley could be a clue about this. and there was the study recently pointing toward the ability of humans to recognize their partner’s approximate IQ. after seeing countless gene/phenotype studies i’m guessing human “choices” are way more deterministic and robotic than most people would ever want to admit. if you carefully piece things together certain things in life even start to seem *inevitable* instead of just being chance. Does anyone think Steve Jobs would’ve settled for being a janitor?
    further, what if certain groups in the U.S. started to bottleneck and become inbred like pure bred dogs? or is that already happening with the autism clusters?

  • Don

    Razib: What is “genetic sorting of classes by merit”?

  • John Emerson

    With education becoming harder to finance, the US has been moving in the direction of less meritocracy / more inheritance for at least 3 decades (I graduated from college 31 years ago and it was already harder when my son entered college 20 years ago). The higher levels of debt people take on also mean that, once they’re out of college, graduates will be less well off because of the debt load. Their job will be meritocratic but their income won’t be.

    College education is a poor index of meritocracy. Wealthy families are favored in admissions and can always afford to send their kids to college, regardless of talent, and versions of the gentleman’s C still exist. Most schools commit themselves to graduating as high a percentage of admitees as possible, and Ivy graduates are pretty frank about the importance of the contacts and connections they make in school, and of the social skills they learn compared to the book learning.

    Wealth has increasingly been going to the top 10%, 1%, .1%, and .01%, with steep increases at each transition. An examination of these groups might partly answer the question, but in general the wealthier and more powerful a group is, the less willing it is to be studied. (Some of the self-made men like Gates actually started in the top 10%, though jobs did not.)

    Class segregation of housing and school funding by district are a powerful and undeniable force against meritocracy. States vary on the degree to which the state equalizes district finances, and that’s a factor that could be studied comparatively. Don’t know about Canada and Australia, but I believe that Britain is relatively unequal.

    There’s finally an entirely different question: to what degree should income level correlate with other factors? How poor should the less-successful be, and how rich should the more-successful be? A pure market economy is sometimes assumed as ideal, but is it? In that economy anyone without work and savings, regardless of reason, would have no resources whatsoever and be entirely dependent on family and charity. Since about 1900 many nations have taken steps to reduce poverty and prevent the development of a dominant wealthy class, and while many regard these measures as wrong that’s not an obviously true belief.

    Not always, but very often those who say that something is inevitable also think that it is good and/or have planned their lives on the basis of the supposed inevitability. The question of social and economic equality and inequality can’t be reduced to meritocratic equality and inequality of ability+effort even in the ideal case (equal economic inheritance and absence of factors of luck).

  • http://entitledtoanopinion.wordpress.com TGGP

    Some evidence that the U.S is not exceptional within the Anglosphere for its treatment of the underprivileged, controlling for ethnic diversity. The full paper is not available online as far as I know.

  • dirk

    Why do US children of highly educated parents score so much higher than their UK, AUS and CAN counterparts?

  • toto

    Dirk: IIUC the graph doesn’t say that US children of highly educated parents outperform their non-US counterparts.

    It says that in the US, children from highly-educated parents are much more likely to occupy the top spots in national test rankings. It says nothing about between-countries comparisons. Even in a world where all US children were significantly worse, or better, that all non-US children, you could still have a similar graph.

  • dirk

    toto: You’re right. The pew report explains it in more detail… though, I should’ve inferred it when they had the middle range set at 50%.

    I’m surprised that the pew report didn’t mention the in-between comparisons.

  • http://lyingeyes.blogspot.com ziel

    There’s finally an entirely different question: to what degree should income level correlate with other factors? How poor should the less-successful be, and how rich should the more-successful be?

    If we look at fields that are highly meritocratic such as professional sports or music, it would appear that the natural tendency is for extreme income inequality between the successful and the average. Even in music there’s lots of people making decent livings as musicians but the superstars make leaps and bounds more. So I think you’re right in your suggestion that a pure market economy would lead to socially unacceptable levels of inequality.

  • ThomasT

    ziel, I don’t think you can just apply the situation in professional sports and music to the rest of the economy. The service of a world class lawyer for example just doesn’t scale the same way a music record does. And with music records losing value due to problems with the enforcement of copyright the inequality in this sector might just shrink again. Live shows don’t scale.

    Regarding “unacceptable levels of inequality” I’m not sure I agree either. Compared to historical levels of inequality western societies are still very equal. The difference to former societies is mainly that the dominant ideology is at least to a degree based on the assumption that you can achieve just about anything if you try hard enough and assigns your “worth” accordingly. But people used to cope just fine with being born into a somewhat fixed hierarchy so I don’t think there is anything inevitable about the relationship between levels of inequality and social problems. It’s just the narrative that might need to change. I think Ludwig von Mises even once made the point that people don’t like liberalism because it takes away their ability to blame others for their failure. We could of course just start blaming genes, but I doubt they would be impressed by that.

  • http://lyingeyes.blogspot.com ziel

    ziel, I don’t think you can just apply the situation in professional sports and music to the rest of the economy.

    Yeah I don’t think so either on a 1-to-1 basis, but it’s quite suggestive. If you look at Razib’s graphic, we might be on that down slope and the “perfect meritocracy” doesn’t look very ideal. More equal society’s seem more unified, so that’s a good thing that we might want to encourage to the detriment of perfect meritocracy.

  • Karl Zimmerman

    As to race, roughly speaking, the U.S. is 64% white (discounting white Hispanics), the UK and Australia are 92% white, and Canada is 84% white. So even though four data points don’t make for a good trend line, there isn’t any evidence in its favor regardless.

    An argument could be made that it has do do with the percentage of the population which is foreign born. After all, immigrants from many countries will have an initial lower level of education than they could otherwise have achieved, and some of their children should excel given the opportunity. However, here too the dataset doesn’t work out well – U.S. – 12.5%, UK – 8.3%, Australia, 23.10%, and Canada, 19.8%.

    You’d probably have to get pretty far down in the weeds to excise any differences potentially due to differing populations. Say, by doing a study across all four nations of test scores for the children of immigrants of Chinese, or Indian, descent.

    One question I have, which isn’t immediately evident looking back at the Pew survey, is what exams are being used to test the ability of children? If they used something like SAT scores, for the U.S., a lot of the performance boost on the top end could be excused by the pervasiveness of test prep classes among the upper middle and upper classes. I have no idea how pervasive test prep is in the rest of the Anglosphere however – I do know Britain has much higher-stakes testing than the U.S., but not the extent to which private test-prep is allowable.

    As to your general point, I have never heard it raised for America, for reasons outlined above by other posters. This probably isn’t the point to debate it, but the general perception is since the 1980s the U.S. has become markedly less meritocratic, in that the big movers for educational mobility (essentially free college, for example) have long since dried up.

    I have heard it suggested, however, that Britain’s high-stakes testing is the reason for the modern-day weakness of working-class politics in the nation. Essentially, with the development of a true meritocracy, most everyone bright was graduated out of the working class. Although this was originally in Labour’s interest (parents wanted their children to have a better shot) it resulted in very few intelligent people remaining in working class jobs. As a result, the cadre of people that would normally form the nexus of trade union leadership, and working-class politics in general (smart people who happen to have jobs “below their standing”) evaporated within the space of two generations.

  • John Emerson

    Compared to historical levels of inequality western societies are still very equal.

    Think of all the different ways that argument could be used to prove that things are perfectly wonderful. Life expectancy, rate of violence, rate of infectious disease, etc. We could roll everything back a century and still be better off than people were two centuries ago.

    There’s an assumption that things have greatly improved in various ways, specifically in the last two centuries or so, and that the gains should be maintained and increased if possible rather than being allowed to disappear.

    Something that never comes out in this argument is that a fair number of people think for a large number of different and often contradictory reasons that a rather high degree inequality is a essentially good thing, but this point of view is almost impossible to advocate or argue and seldom is openly stated.

    The difference to former societies is mainly that the dominant ideology is at least to a degree based on the assumption that you can achieve just about anything if you try hard enough and assigns your “worth” accordingly.

    Equality of opportunity is the characteristic American form of normative equality, but there are other points of view that no one should be allowed to sink too low, and some also think that no one should allowed to rise too high, especially in terms of having too much power.

    But people used to cope just fine with being born into a somewhat fixed hierarchy so I don’t think there is anything inevitable about the relationship between levels of inequality and social problems.

    There’s a general feeling in the US that the caste system or medieval feudalism are not good models for us. Feel free to disagree.

  • John B.

    When I look at those graphs, I see the same curve stretched different amounts. In other words, I suspect that the definitions of high-, mid- and low-educated are either different in the four cases or they are the same but select different ranges of people.

    As an example, if a larger fraction of people in the US go to college than in Canada, then “mid” in the US would includes more college graduates and “high” in the US would be enriched in more advanced degree holders while “low” would be enriched in drop-outs.

    There’s a lot of adjustment required to make these comparisons mean anything. Did they do that adjustment?

  • S.J. Esposito

    As a somewhat related side note, there’s an interesting — albeit despicable — series of events coming to light right now regarding high schoolers from affluent Long Island families caught paying others to take college entrance exams and undeservedly being admitted to some very good schools. When I first heard, I immediately wondered about how often that happens. My guess is much, much more than we hear about.

  • DK

    Genes may account for some of the overall difference between rich and poor kids, but not for the difference between Canada and the U.S.

    Really? The data is not stratified by race. But blacks are 13% of population in the USA and somewhere between 1 and 3% in Canada. The proportion of Asians in Canada is almost twice higher than in the USA. Plenty of room for there to be genetic differences between USA and Canada!

  • http://washparkprophet.blogspot.com ohwilleke

    Looks like a “grading on a curve” effect to me.

    Canada is more homogeneous than Australia which is in turn more homogeneous than the U.K. which is in turn more homogeneous than the U.S.

    When you set the middle ground to be identical, the statistical remainder is basically a mesure of how much variance there is in the sample. The U.S. has higher highs and lower lows because of its much, much lower levels of homogeneity.

    Since this particular study is measuring vocabulary, one obvious place to look for lack of homogeneity is in parental English language skills.

    The U.S. has an immense number of immigrants whose native language isn’t English and who aren’t highly educated. This kind of immigrant is present, but in lower percentages in the U.K. This kind of immigrants is considerably more rare in Australia. This kind of immigrant is more rare still in Canada.

    Notably, this requires no resort to genetics.

  • Doug1

    Genes may account for some of the overall difference between rich and poor kids, but not for the difference between Canada and the U.S.

    Hispanics graduate from high school and four year colleges at lower rates than blacks. Blacks and Hispanics make up 29% of America’s population now. Seems to me that that alone might account for much of the effect shown in the first chart.

    An argument could be made that it has do do with the percentage of the population which is foreign born. After all, immigrants from many countries will have an initial lower level of education than they could otherwise have achieved, and some of their children should excel given the opportunity. However, here too the dataset doesn’t work out well – U.S. – 12.5%, UK – 8.3%, Australia, 23.10%, and Canada, 19.8%.

    I’d expect the greatest social mobility in Canada as a result of the immigrant effect because they tend to screen for immigrant skills/(IQ in effect) the most of the countries listed. And voila. Australia gets a lot of bright Chinese but they also get lots of others from Muslim countries with not such high average IQs.

  • AG

    >In other words, the correlation will increase in a perfect meritocracy, and social mobility will decrease!

    That makes perfect sence. That also explain big upheaval or social mobility when definition of `merit’ changes.

  • http://washparkprophet.blogspot.com ohwilleke

    “However, here too the dataset doesn’t work out well – U.S. – 12.5%, UK – 8.3%, Australia, 23.10%, and Canada, 19.8%. ”

    In the U.K., Australia and Canada many of the foreign born are from the United States or from Commonwealth countries where English is either the primary language (e.g. NZ and Canada and UK for Australia) or is at least a language of elites (e.g. India or Pakistan or Kenya) in that country. The U.S., in contrast, has immigration mostly from places where neither is the case (Latin America and China are near the top of the list). Further, the U.K. rather than Australia or Canada, get the lion’s share of Commonwealth immigration from places where English is merely a secondary language.

    Non-English speaking, well educated immigration should dampen English vocabulary among the highly educated relative to poorly educated people.

  • pconroy

    @25,

    Here is some demographic info on Indian and Chinese diasporas:

    http://www.economist.com/blogs/dailychart/2011/11/diasporas

  • Karl Zimmerman

    Razib,

    Saw this study today, which speaks to some of the hypotheses people have been throwing around.

    My quick takeaways.

    1. The gap between test scores of the rich and poor has risen rapidly since the 1940s.

    2. The gap between black and white test scores has actually fallen significantly on reading, and to an extent math.

    3. Oddly, the gap in test scores between the rich and poor first shows up in kindergarten. One would expect if there was a “nurture” effect, the gap would rise as rich parents tried to get their “gifted but learning disabled” children up to par.

    4. The gap between test scores of children of highly-educated parents and everyone else has not grown dramatically.

    5. The author notes that the trend has been constant. If rising inequality actually caused the test score differences, you’d expect a spike in the 1980s, which doesn’t happen.

    I’d actually say the best fit of this data is that perhaps we are getting closer to a meritocratic structure, as you posited. The author doesn’t seem to take hereditary possibilities into account in his conclusion however, making no strong conclusions, but noting the rise in focus on early childhood education among the upper middle classes.

  • Mark Peifer

    While I do not discount genetic differences in the traits measured, the idea that we are anything approaching a meritocracy is contradicted by the data. Do you think genetics also is the reason for the differences in infant mortality or life expectancy,

    Here’s an article from 2008 with some data

    http://www.nytimes.com/2008/03/23/us/23health.html

    Also, I doubt anyone could argue that genetics leads to changes in the 20 year range–as has been seen in an increased gap in life expectancy.

    Early literacy is a key factor in the scores we see (it IS manifest before the kids start kindergarten–sorry!), and it has dramatic disparities in which parental education and income level play a key role.

    http://www.jstart.org/site/DocServer/America_s_Early_Childhood_Literacy_Gap.pdf?docID=3923

    I have watched my own children go through public schools and have seen children with equal excitement about learning at age 5 diverge as they move through elementary school, as some have advantages at home the others don’t. For high school students, the expectation now is that they have a personal computer at home, internet access, all the latest programs, a printer, not all of which is accessible to all.

    Political views ahve an affect on how all of us view data–we need to be careful on both ends to not cherry pick the data that fits our views. I’d also encourage those of you who think we live in a meritocracy to go volunteer as a reading helper at a local public elementary school that actually represents the US at large, and see what you think after you meet kindergartener’s already “predestined” by our system to fail.

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Gene Expression

This blog is about evolution, genetics, genomics and their interstices. Please beware that comments are aggressively moderated. Uncivil or churlish comments will likely get you banned immediately, so make any contribution count!

About Razib Khan

I have degrees in biology and biochemistry, a passion for genetics, history, and philosophy, and shrimp is my favorite food. In relation to nationality I'm a American Northwesterner, in politics I'm a reactionary, and as for religion I have none (I'm an atheist). If you want to know more, see the links at http://www.razib.com

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