Heritability and twins, yet again

Slate’s Brian Palmer has written an astonishingly ignorant critique of the use of twin studies to estimate the heritability of complex traits. Razib has a pithy response, in which he refers to the Slate piece as “a sloppy mishmash”: there’s just so much wrong with the piece (beginning with its first sentence: “One of the main messages of science over the last couple of decades is that genes are destiny”) that it’s hard to know where to start pulling it apart.

Fortunately there’s no need for a point-by-point response here: Luke wrote a lengthy response to another ignorant critique of twin studies late last year, and his cautious defense of the methodology is just as pertinent here. In addition, it’s been reassuring to see that the comments thread at Slate has been almost universally negative.

As Luke noted last year, there are some valid criticisms that can be pointed at twin studies, although none of these fundamentally undermine the value of these studies for understanding human genetics. It’s a shame that Palmer chose to ignore these substantive criticisms in favour of sweeping dismissals and eugenic slurs.

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8 Responses to “Heritability and twins, yet again”


  • My God, that article is a disaster. I couldn’t even finish it because I had become so angry by the time I was halfway through that I was no longer literate. The comment threads were an interesting mix of people (most of whom must be geneticists) who couldn’t believe Slate would publish such garbage and others who kept demanding the detractors to point to specific objections and back them up with proof. The problem is that nearly every sentence is fundamentally wrong!

  • Maybe worth pulling out a few of the most egregiously wrong or misleading statements. This was a really awful piece:

    “Identical twins also have different mitochondrial DNA, the genetic information stored in the cellar organelle responsible for processing glucose”

    “Twin studies also rely on the false assumption that genetics are constant throughout one’s lifetime…By the time a pair of twins reaches middle age, it’s very difficult to make any assumptions whatsoever about the similarity of their genes.”

    “The most well-studied difference between monozygotic twins derives from a genetic phenomenon known as copy number variations. Certain, lengthy strands of nucleotides appear more than once in the genome, and the frequency of these repetitions can vary from one twin to another. By some estimates, copy number variations compose nearly 30 percent of a person’s genetic code.”

    “researchers continue to crank out new papers, probably in response to a public demand—both insatiable and inexplicable—for evidence that we’re just like our parents. “

  • i think he must have been commissioned to write the piece with that stance. it looks like he made a few contacts and googled his way to the rest. a lot of it is in the “not even wrong/what does that even mean?” class.

  • Well, some of you know my somewhat strong feelings about the people who want to discredit DNA as an influence on health as they raise money for their environmental causes and their desire to sell you detox potions. This is slightly different to me, but I think there’s a thread of similarity.

    It seems to me this is part of a backlash against genomics that we are seeing brew. Some of it is unfocused at this point, some (like the newborn screening stuff is more directed). But I think it is a Gattaca-fueled fear of stuff that people are hearing more and more about, but don’t really understand. People are going to attempt to pick at the edges to relieve their anxiety about their genes and what we’ll be finding.

    It won’t all end up on the path of the anti-vaxxers, but a portion of it will. It is not clear to me how to affect that–and it may be impossible, really.

  • Jacob Weisberg, the editor in chief of Slate, bears full responsibility for publishing this scientific abomination by Brian Palmer. It seems that Mr. Weisberg is a Harvard graduate, so it is truly shameful that he has given a platform to such a Know-Nothing in the middle of the current pitched debate over NIH funding.

    Twin studies assist us in curing disease and help us understand the limits of genetic causation; to denounce them for imagined political implications as Mr. Palmer so unfortunately does is reminiscent of the ugly eras in which Einstein’s work was attacked as “relativistic Jewish physics”, and when Soviet commissars executed geneticists for the crime of supporting Mendelian inheritance and opposing Lysenkoism.

    Mr. Weisberg must be called on to engage the scientific community directly on an issue of such importance from this point forward. The scientists at Genomes Unzipped, especially Luke Jostins, would almost certainly be able to assist Mr. Weisberg in finding people far more capable of understanding the literature than Mr. Palmer.

  • My solution is that I generally don’t read the popular press for scientific articles, with the exception of Nicholas Wade of the New York Times. Out of sight, out of mind.

  • Addendum:
    For scientists, and particularly clinical genetics, it would be useful to have a journal of replicated results, and perhaps have a $500 fine per scientist for each paper released that stretches the data or whose methodology can never be replicated.

  • i think davis plotz is the current editor.

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