Knowledge of heritability, ignorance of genes

By Razib Khan | December 8, 2010 8:47 am


Does the Slut Gene Exist?
:

The DRD4 study isn’t an isolated case of shaky genetic science. In fact, it joins a cadre of questionable scientific assertions that link single genes to much broader patterns of behavior.

The last decade has witnessed an explosion in genetics studies, and with it, a proliferation of sensational study results that run the gamut from disingenuous pop-science to borderline science fiction. In the past 10 years, we’ve heard about the God gene that allegedly explains religiosity; the warrior gene that supposedly makes those who have it more aggressive when provoked; and the liberalism gene, a single gene that, we’re told, predisposes a person toward joining a particular political party.

Fair points. See my post from yesterday. But I’m not sure about this:

“There are economists publishing papers saying whether you’re conservative or liberal is an inherited trait. It reminds me of the old eugenics trope which was, poverty is inherited. Well, of course!” says Misha Angrist, the author of a new book….

There’s a subtle point here. Economists may assert that political disposition is heritable, which is a subset of the inheritance you receive from your parents. It is the component which can be attributable to variation in genes, even if we don’t know the genes in question. There is no “height gene.” But we can agree that in the United States most of the variation in height is due to variation in genes (~80-90%).

Long story short: there may not be a “slut” gene, but “sluttiness” may still be heritable.

CATEGORIZED UNDER: Behavior Genetics
  • omar

    Spot on..

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  • http://blogs.plos.org/genomeboy Misha

    I was not trying to equate traits that are taught by parents to their children with those that are mediated by genes. On the contrary. The point I was trying to make was that some economists confuse the two. They have been seduced by genetic determinism just as so many journalists have been when they refer to “slut genes”: there’s a belief that if one gets a bunch of people, genotypes them for DRD4 (or the gene of the month) and then asks them how they voted or how many people they’ve slept with that this will yield some profound–or at least newsworthy–insight into human behavior, even without controlling for environment or cultural norms.

    As for height genes, yes, height is highly heritable. But there are thousands of genes that contribute to height. Most of what we know about behavioral genetics suggests that “sluttiness”–if we can even agree on what that phenotype is–will not be mediated by a single gene on its own in a meaningful way. That was my point and I think also the author’s point.

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

    even without controlling for environment or cultural norms.

    a minor note, but a lot of the stuff out of sweden should control for cultural norms. that’s a criticism in fact since they eliminates G X E.

    misha, my last sentence make what you’re saying explicit. i think people do need to be told this explicitly too. they naturally confuse genetics with singular genes :-)

  • http://washparkprophet.blogspot.com ohwilleke

    One of the fascinating parts of the development of genetics, however, is that every once and a while we do catch single genes that do unequivocally produce some trait that had widely been believed to have very complex causes, while other traits that seem like they should have a simple genetic cause because they are so heritable and distinctive turn out to be far more complex than intuition would suggest.

    For example, a really remarkable share of all language related learning disabilities (no it isn’t the entire suite or entirely deterministic, but it is a very large share of the total observed phenomena) boil down to which pair of FoxP2 genes you have, despite the fact that one thinks of language as being a highly culturally driven and complex phenomena.

    A single“fruitless” gene in fruit flies can flip their entire suite of gender identity specific behaviors. Another can put a new leg or eye in a part of their body where you wouldn’t expect one – the blue prints for making legs or eyes are apparently someplace else in the genome than the part of the genome where the large scale body plan of a fruitfly is laid out.

    Yet, some of the most symptomatically distinct and reliably diagnosable mental health conditions, like autism and schitzophrenia, which happen to have some of the strongest heritable components, both factors which would seem to argue for a very simple genetic cause (something that is, for example, the case with many of the most common varieties of congenital mental retardation), turn out to have extremely complex patterns of causation that make them start to look like the fevers of hereditary conditions — symptoms that characteristically emerge when there is too high a cumulative level of mutation in key parts of someone’s genome, rather than a particular useful tool for distinguishing one cause from another.

    The distinction sheds light on the architecture of our genetic inheritance, and may also eventually be important medicinally. Gene therapy to address a hereditary condition with a single gene that causes it may be viable in the not so distant future. A single gene condition is also much more obviously a candidate for non-gene therapy based treatments because it allows for a very neatly pinpointed hint about the biochemical path by which the condition arises that can then be interrupted at any step. Hereditary conditions that are a product of dozens or hundreds of genes may be less amenable to that kind of treatment.

  • http://theunsilencedscience.blogspot.com/ nooffensebut

    “In the past 10 years, we’ve heard about the God gene that allegedly explains religiosity; the warrior gene that supposedly makes those who have it more aggressive when provoked; and the liberalism gene”

    How many points is each example worth? It sounds like she is unaware that “the liberalism gene” is “the slut gene.” In fact, it is also one of the five genes that Beaver et al found to collectively have a more significant association with violence in adult African-American men than their childhood relationship with their mothers. She equates a one-off study on “the liberal gene” with the nearly 20 years of research on “the warrior gene,” MAOA. I am open to what genome-wide association studies ultimately conclude about just how much any particular gene contributes to the supposedly “complex” behavior of impulsive violence, but I have serious doubts that the warrior gene will stop being the warrior gene. Not only does it have a thoroughly replicated gene-environment association for the 3R allele (which I summarized here), but it also has an understudied but undisputed main effect for the 2R allele, a human and mouse knock-out violence syndrome called Brunner’s syndrome, and corroboration with the association between the enzyme’s urine metabolites and violence. If MAOA does not affect behavior or thought, then maybe we should stop prescribing MAOA inhibitors for depression. Some of your readers may have experience with a nonprescription form of MAO inhibitor, cigarettes. These kinds of politically correct pretentious diatribes against behavioral genetics float up every several months. If the authors read the previous entries to the genre, they might improve upon it.

  • http://www.thethinkingman.org Al Feersum

    Seems to me cultural behaviour bias, when applied to genes, sounds very Lamarckian – even though inherited genetic ‘learning’ does happen with microorganisms (especially pathogens!), I really can’t see it happening with social attitudes. Maybe a genetic susceptibility to be open or closed minded (liberalism), or, indeed, be a more prolific breeder (more sex please!), but these in turn will be affected by the cultural norms of the locality.

    Sure, there are certain inherited conditions that will prevent promiscuity (though they may indeed be in conflict with ‘prolific breeder’ genes), or force people to be less open minded (non-liberals), or even make people more intelligent than the baseline (and at the same time, be socially retarded, thus making the the individual appear stupid), but claiming that a single gene is implicated is irresponsible.

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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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