Sunday, June 9, 2013

Four (Wrong) Ways To Interpret Links Between Genes and Education

Last week Science published a neat little paper examining links between specific human DNA sequences and educational attainment. The paper, which is a bit shorter than the list of authors who worked on the project, examined a total sample of more than 120,000 participants who had their entire genome sequenced for a number of small clusters of repeating nucleotides (single nucleotide polymorphisms or SNPs). They then examined all the SNPs and their associations with the level of educational attainment of each of the participants in the sample. After controlling for bias, in that a genome wide study performs thousands of significance tests, three SNPs emerged as significant predictors of educational attainment.

I find this study very interesting because there are a number of provocative ways to interpret the results of this study, and most of those would be incorrect! In what follows, I highlight four (wrong) ways to interpret the results of this study.

I. HA! At last there is proof that genes do influence education attainment!
The first reaction to this result is likely to be a confirmation of something we all know intuitively--our genes influence our behavior, and in particular, the kinds of behaviors that are associated with longevity in school (e.g., perseverance, cognitive ability, work ethic). Unfortunately, its not a good idea to interpret this study as definitive evidence that genes influence educational attainment. Sure the sample of 120,000 people is pretty impressive, but the reality is that the three significant SNPs account for roughly 2% of the variance in participants' educational attainment--or about one extra month of schooling. Not a huge genetic impact on educational attainment, which then might lead someone to conclude...

II. HA! At last there is proof that genes don't influence education attainment!
It seems reasonable to conclude that if SNPs only account for 2% of variance in educational attainment, then they don't matter in the grand scheme of our educational lives, but that would also be an incorrect characterization of these findings. This specific study is a genome wide association study that looks for associations between SNPs and a specific phenotype. The method assumes that there will be relationships between a specific repeating DNA nucleotide sequence and a behavior. This of course, is not the only way that genes can influence us: For instance, genes can have additive effects, can interact with each other or the environment, can be switched on and off by changes in the social context, can mutate, and on and on. This specific study doesn't account for these more complex genetic influences--genes still are very much in play when it comes to educational attainment.

III. This research validates previous SNP studies!
You might be tempted, at this point, to conclude that the results of this study provide further validation for similar work that examines associations between specific SNPs and behavior. Most people are aware of SNPs like those that predict Alzheimer's Disease risk (APOE-4) or that relate to the number of oxytocin receptors in the brain (rs53576). But this specific study, if anything, is actually critical of much of this prior work.

If exploring the entire genome yields specific SNPs that only explain 2% of variance in a given behavior, then that behavior is either uniquely not influenced by genes (see point II above) or SNPs are not likely to be powerful predictors of behavior to begin with. Thus, studies that examine specific SNPs should be using a much larger sample than they have previously (try 120,000).

IV. Gene researchers shouldn't bother with SNP studies
Before you go throwing out the baby with the bathwater, it is important to note that some SNPs are powerful in predicting behavior--though they are fairly rare. The one example is the APOE-4 SNP that predicts Alzheimer's Disease. There are likely others, so this type of research isn't a lost cause. The question of whether a specific SNP sequence will reliably influence complex behaviors that people study in social and personality psychology remains a mystery.

I hope this post helps you understand a little bit about gene research and some of the pitfalls in studying and interpreting genes in the context of complex behaviors like education attained. Still, this Science paper has to be one of the best examples of the right way to do gene research. That's progress in my estimation!

Rietveld, C. A. (2013). GWAS of 126,599 individuals identifies genetic variants associated with educational attainment Science


  1. Good posting. But the wording of Item 1 ("HA! At last there is proof that genes do influence education attainment!") is kind of silly. We already know that fluid IQ has extremely high broad heritability and enormous impact on people's ability to profit from education. (The fact that it is hard to find the indiv genes responsible for its heritability does nothing to call that into question. The same picture emerges with many medical conditions: high broad heritability as revealed by twin studies, but extremely polygenic with weak indiv gene effects.)

    1. That's a fair point, that we have known about the heritability of IQ and educational attainment for a while. I would argue though that failures to find specific genes might lead some to become skeptical about previous twin work (i.e., the missing heritability problem). One could argue that twin studies don't rep the population, or they are accounted for by some unmeasured environmental factors.

      I'm not arguing that, but what I am saying is that finding specific candidate genes is not the final piece of evidence that confirms the twin data. Still a long way to go to figure out how genes influence education (e.g., additive, multiplicative, mutation, etc...). Neat study in any case!

  2. I'm not sure why you'd say (in Point I) that we shouldn't be certain that genes influence education - we've known from twin studies that education is strongly heritable, for a long, long time (see, e.g.

    The point of these SNP studies is to find the SPECIFIC genes that account for the heritability of education. This particular study is a great first step in doing so.

    1. I didn't mean to suggest that we shouldn't be certain that genes influence education, we should be certain that they do. What we are not certain about is which genes and in what ways do genes influence education attainment.

      I would argue though, that genetic influences are certainly more than 2% when it comes to educational attainment, so this first study, though important to the research world of SNP work, is still not there in terms of revealing the importance of genes and their process of influence on our phenotypes. I think that is one of the larger points of the paper!

  3. It is a very interesting correlational study between genes and education. It is hard for me to believe that there is a relation between genes and education. Those 120000 people were taking randomly. There must must be so many uncertain factors in the study, such as the per capital standard of living, the government's emphasis on education, the their culture of education.

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