Bryan Caplan  

Are Neighborhood Effects Really Genetic Effects?

Mind Wide Open... Liberals and Walmart...

A new paper leads Tyler Cowen to ask: "Are Neighborhood Effects Really Family Effects?" But I'd say he's suffering from what I've called "environmental bias." Since the whole behavioral genetics literature has already found shockingly weak evidence of family effects (for primers, see here and here), these findings are best interpreted as more evidence that the main cause of inequality is genetic.

COMMENTS (14 to date)
Mr Java writes:

I think Byran, your going to have to explain what you mean by that. Obviously, it is a short sentence and thus not very nuanced. The main cause of inequality is genetic? Oh? So, in the days of feudalism, was the main cause of inequality genetic? Perhaps lack of opportunity had more to do with it at that time. That seems more plausible to me.

Today, we have not fully moved away from a situation where the social status and opportunities that ones parents have largely influences the social status and opportunities of children. In other words, just as in feudalism, position matters. (Though, thankfully, much less so.) That is not inconsistent with a genetic explanation. However, if you look at the actual mechanism by which opportunity flows to the children of those who are better off, genetics does not seem to be a persuasive explanation in countless cases. For example, networking opportunities that flow to children are not the result of genetics. Legacy preferences granted by ivy league colleges are not the result of genetics. Having access to capital to start a new business is not the result of genetics. Going to an elite boarding school that has a superior environment for rigorous learning is not the result of genetics. I could go on and on with examples where genetics is not a very good explanation for the resulting inequality.

Whether you think that genetics is the "main cause" of inequality or not, it is clearly not the only cause. That is indisputable. So, the question is how do you support your assignment of greater weight to genetic factors versus other factors that cause inequality. Obviously, your short and superficial blog entry does nothing to justify your decision to weigh genetic factors as you do. Plus, I should mention that you need to define "main," which itself is a somewhat arbitrary act. Certainly, even if genetics was the "main" cause of inequality in many individual cases, it would not be the "main" cause in many other individual cases. So, when you say "main" do you really mean "most common." And is such imprecision on your part acceptable. Am I supposed to take your economic conclusions seriously when you are this sloppy when discussing this topic? Obviously, sloppiness when discussing one topic does not inevitably imply sloppiness when discussing another. But experience shows that those who are sloppy discussing topic A have a higher probability of sloppiness discussing topic B. If I were you, I would avoid superficial spewing forth of unsupported opinion, even on a blog. It tends to damage your credibility. (I wonder if your lack of good judgment here is caused by genetic factors...)

eric writes:

No one's arguing environment has no effect, but Bruce Sacerdote did a neat estimation of the relative effects by looking at the outcomes of biological children vs adoptees, over at

From the Abstract:

I calculate the transmission of income, education and health characteristics from adoptive parents to adoptees. I then compare these coefficients of transmission to the analogous coefficients for biological children in the same families, and to children raised by their biological parents in other data sets. Having a college educated mother increases an adoptee's probability of graduating from college by 7 percentage points, but raises a biological child's probability of graduating from college by 26 percentage points. In contrast, transmission of drinking and smoking behavior from parents to children is as strong for adoptees as for non-adoptees. For height, obesity, and income, transmission coefficients are significantly higher for non-adoptees than for adoptees.

anony writes:

The fact that we're seeing genetics and heredity pop up in many different measurements is probably a good sign. Assume that you make perfect progress towards eliminating every environmental effect that produces inequality, then by definition, what you have left isn't environmental.

I'm not saying we're anywhere near that Utopia, but on MLK day one should acknowledge that a lot has changed in a century. Inevitably, genetics (which we still have a limited handle on) should loom larger in the observed measures on inequality. Indeed, I sadly predict that the closer we get to Utopia, the angrier people will get over the differences that can't easily or cheaply be changed.

Ramon writes:
...Assume that you make perfect progress towards eliminating every environmental effect that produces inequality, then by definition, what you have left isn't environmental.

True, but intelligence is priced by the market mechanism according to supply and demand. Markets translate inequality in IQ into inequality in income. Institutional arrangements other than pure markets imply a different transformation function resulting in different income distributions.

The statement "genes are a source of inequality" is in general true, although different institutional arrangements imply a stronger or weaker effect. Public policy can aim at "flatening" the genes-to-income transformation function.

For instance, in South Africa's Apartheid era, income inequality was strongly caused by genetic differences (white, colored). But this was largely a result of the institutional arrangements.

T.R. Elliott writes:

Mr Caplan: Have you read the nurture assumption? I read analysis of it when the book came out and in looking at it again find that the author does not at all negate nurture. Yes, she minimizes family effects, because she finds peers to be more important. Therefore she proposes that parents steer their children towards the right peer groups. That does not negate environmental influences, it simply moves it from family to peers and larger community.

So in looking at this one reference you provide, as far as I can tell, you've made an egregious error.

Your second reference is to yourself. Quite convenient. Which then leads to speculation.

Speculation and opinions. Of little value.

Ivan Kirigin writes:

Funny how often people disagree when claims are made that genetic differences cause differences in outcome. I'm just waiting for Steve Sailor to comment about how brave Brian is for this post :)

Clearly 100% genetic in 100% of cases for any matter (income, intelligence...) is wrong.

Today, the PC view is that it's 100% nurture, justified by claiming a lack of government intervention in cases of individual failure (regardless of cause). Every unemployed person is the government's responsibility. Every child must go to college.


T.R. Elliott writes:

Ivan Kirigin: I believe there extremists on both sides of this argument, e.g. Mr Caplan with his comment "main cause of inequality is genetic" and others on extreme left. But I think a majority of people are smart enough--through nature or nurture--to know that there are many with genetic predispositions who do not have the opportunity and many as well who are not genetically capable of many activities and accomplishments--e.g. someone with down syndrome.

But I hear more people on the left discussing issues such as living wages, not equal outcome for all.

But people should reflect on this phrase: "main cause of inequality is genetic."

Brave is not the word that comes to mind.

Alberich writes:

TR Elliot

Huh? Caplan references both the nurture assumption book by Harris and a book on twin studies by Segal (the second link, right next to the Nurture assumption link, which either you missed or decided not to click.)

The self-referential link is called good blogging so that we (the readers) don't have to google search the site if we are interested in the referenced earlier post.

I will agree with you though, I thought the nurture assumption doesn't claim a genetic basis but just shifts the environmental determining factor away from the partners to the peer group. The nurture assumption is then not evidence of gentic factors unless peer group susceptibility is genetic. Can anybody clear that up?

RabbitAngstrom writes:

Re the first comment on this thread:

If we could count the cases of legacy tipping admission to the Ivy Leagues in favor of an applicant this year, I bet it'd be less than 100. If we counted the cases of affirmative action tipping it, for the eight Ivy Leagues schools the number would be in the thousands.

Legacy admissions, as Steve Sailer has pointed out, are far less common than racial quota-based admissions, since legacy admissions are non-*transferable*. If Dad's going to, say, Emory has some pull on you getting in, then great, but it won't help you at UNC-Chapel Hill, Duke, or Michigan. But being black helps BIGTIME at all three.

So that particular environmental advantage is off the table, unless someone's got a great counterargument, since it's actually an environmental disadvantage, unless you're black AND legacy!

resigned writes:

I think this thread misses a rather large point. Are there genetic links to ability--of course. Do environmental factors influence ability--of course. Stick a slow kid in a nurturing environment and he'll probably do better than if he's put in a poor home environment. However, these all miss the fact that the US does not exist in an economic vacuum. Imagine that you have country A which makes efficient use of most of its population as compared to population B which doesn't educate its women. Which country is going to be more productive (here there are tradeoffs, but on net, I gamble that the productivity is going to still be higher for the population using its full resources). Long term, our country cannot afford to leave people behind who are capable of being efficient and moving up the economic ladder. It's wasteful. Affirmative action is a bandaid on that problem which cannot be effecting a significant portion of the population. Improved K-12 education and parental involvement seem far more important to me in the long term for addressing the underlying problem. In some districts which actively work towards closing achievement gaps, there have been improvements (as measured by SAT scores, etc.), though not parity.

Aside: Legacy admission is a bit of a red herring. I think that the cultural capital that people from different income classes is more important. I have two friends who are married. One has a phD in physics who is now working for morgan stanley. The other has a phD in physics who is working in a computational job. They have a 9 year old daughter. She is very intelligent and has been exposed to a number of friends of the family from similar backgrounds. While it is not guaranteed that she will be sucessful, her background makes it likely--not just due to financial background, but due to cultural capital. Now, there are of course poorer families which value education and push their children towards success (for example my grandparents had 8th and 4th grade educations, worked in low skilled jobs, but all of their children went to college, because they pushed education), but is it as likely? Looking at many people that I've met, I'd say no. I think a good question is, how to instill certain cultural values that will lead to success, regardless of parental background--or, is it not possible?

nn writes:
Imagine that you have country A which makes efficient use of most of its population as compared to population B which doesn't educate its women.

This confuses technical and economic efficiency. Under certain economic and social conditions, it MIGHT be optimal to let certain groups be undereducated. Our objection to allowing women not to study is moral not economic. It is a mistake to assume otherwise. This is the fallacy Galbraith made saying that the Soviet Union used their workers more efficiently because they had "no" unemployment.

The relevant question is to allow efficient matching in a competitive marketplace with full enforcement of contract. You may have other "social" reasons for regulating this (preference for equality or a minimum wage) but don't confuse this with efficiency.

Similarly, the returns to cognitive skills and other talents will vary with the system. Hence the nature of inequality will change. But the fact is that the inequality that remains will still be tied to some characteristics that are difficult to influence environmentally. The more equal the environment, the more those unchangeables will determine the inequality that remains.

I also believe that in all modern, developed socieites (even regulated welfare states), cognitive skills on narrow g tests are positively correlated with performance. This may also be true for poor countries though in these cases environmental factors are more important as you would expect if large fractions of the population are malnourished.

Half Sigma writes:

Genetic intelligence has the biggest influence on test scores. I'd rank the kids' friends second and family third. But who the kids hang out with is strongly influenced by their intelligence and family's social status.

resigned writes:

sigma/2, you know this how? I would say parents have a huge influence on their kids sucess. I'm a lot more successful than a number of kids I grew up with--not because I was smarter, but because I worked hard--because my parents expected it of me and encouraged me to do my best in school. My friends parents were not as involved and even though they were smart, by around 4th grade, their performace seriously dropped off.

nn--You raise a good point, but I still argue that there is an efficiency issue. It's a numbers game as to where innovations will come from. I think the more people you have pushing the envelope, the better chance that someone will break through.

nathan writes:

But wouldn't your genetics make you work hard? Plus, your parents encouraged you which is part of their genetics. Being able to raise and nurture children is a personality trait that I believe is inherited through genes. Of course, environment plays role, but genetics determine how you deal with your environment.

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