
Most Reported Genetic Associations with Intelligence are Probably False - tokenadult
http://dash.harvard.edu/bitstream/handle/1/9938142/Most_Reported_Genetic.pdf?sequence=1
======
Xcelerate
Note that the article is _not_ saying that intelligence is not heritable. In
fact it makes it quite clear that despite the controversy, the opposite is
true:

> Although the exact figures have been the topic of much debate, the claim
> that IQ is at least moderately heritable is widely accepted. IQ may in fact
> be similar in heritability to the physical trait of height

What the article _is_ saying is that intelligence cannot be tied to
_particular_ genes:

> We sought [and failed] to replicate published associations between 12
> specific genetic variants and g using three independent, longitudinal
> datasets

It just goes to show that there isn't necessarily one particular factor you
can pick out to predict intelligence; it is a combination of many things.

(I shall attempt to avert the impending discussion about the word
"intelligence" by clarifying that the sense I am using that word is in the
same specific manner that the article is: as an objective measure that is
statistically correlated with other measures).

~~~
bayesianhorse
For all practical purposes, "intelligence is largely not heritable" is
actually closer to the truth than the opposite.

As long as you can't tie intelligence to particular genes, as long as you
can't tell what amount of intelligence in an individual is inherited, and how
much isn't, there is no use for this in education, politics or social welfare.

What I see the argument being used for, mostly, is to justify racism and
entitlement issues in wealthy people...

~~~
rayiner
IQ is highly heritable:
[http://en.wikipedia.org/wiki/Heritability_of_IQ#Estimates_of...](http://en.wikipedia.org/wiki/Heritability_of_IQ#Estimates_of_the_heritability_of_IQ)
(estimates of adulthood heritability are 0.7-0.8, similar to height).

We can reject the existence of an observed natural phenomenon because we can't
explain it. We still haven't unified gravity with the standard model, but that
doesn't mean we reject that gravity exists (for practical purposes or
otherwise).

The fact that a natural phenomenon might be socially inconvenient is even less
of a good reason to reject its validity.

Finally, I don't even see why it should even be so socially inconvenient. Say
the experiments are right, and intelligence is mostly heritable rather than a
result of education, upbringing, etc. Why should that justify entitlement on
the part of the wealthy? Indeed, it should cut across that grain. If its
mostly heritable, being intelligent shouldn't be seen as intrinsically
virtuous any more than is being tall. Moreover, the heritability of
intelligence may very well imply a need for a change in our priorities when it
comes to social welfare. E.g. maybe we need to de-emphasize education, and
divert resources to building up social and family networks.

~~~
bayesianhorse
I qualified my statement with "for all practical purposes". I have often
claimed that there is no practical relevance and no reasonable way to use this
"fact" in practical real world decisions. Nobody was able to tell me one that
holds up to even superficial checking.

"Socially inconvenient" doesn't even come into it, because twin studies don't
tell us anything about differences between two ethnicities. For that matter,
genetic diversity within populations might have a larger effect...

The "intelligence is genetic" "fact" is often used to justify refusal to
tackle socio-economic problems (like "under-achievement" in blacks or
hispanics in the US, or the turkish minority in my home country) with socio-
economic solutions. Because hey, it's all genetics, so we can't change it.
Even if measures for improvement have been proven...

~~~
jcampbell1
"intelligence is genetic" and "intelligence is heritable" are completely
different statements. The notion that IQ is fixed and encoded in genes is
nonsense. What is true is that for a given environment, the variation in
observed IQ is strongly explained by genetics. It is possible, and likely
true, that lower intelligence among minorities is caused by the environment,
but that the variation among those in this environment is explained by
genetics.

The fact that intelligence is heritable says nothing about social-economic
policy for changing the environment. It is as absurd as saying that because
"height is genetic" there is no reason to worry about malnutrition.

------
btilly
This whole field seems likely to be a case study supporting
[http://xkcd.com/882/](http://xkcd.com/882/).

But the research does have a questionable assumption. On p 5 it says, _" Such
a result would not likely be due to differences in the methods used to
generate g in the various datasets under comparison, since g is consistently
measured by a wide variety of tests."_

This is true. However it is also true that, as
[http://vserver1.cscs.lsa.umich.edu/~crshalizi/weblog/523.htm...](http://vserver1.cscs.lsa.umich.edu/~crshalizi/weblog/523.html)
points out, that all evidence we have is consistent with g being a correlation
between different ways of weighting a large number of independent factors. If
so, then it is easy to have two test measuring g that are fairly well
correlated with each other, one of which picks up a particular factor and the
other does not. If a gene affects that factor, then the test you use to
measure to find these correlations will matter.

~~~
epistasis
> This whole field seems likely to be a case study supporting
> [http://xkcd.com/882/](http://xkcd.com/882/).

The scientifically interesting thing is that it's not at all like that XKCD
cartoon. Multiple hypothesis testing is built into the design of the studies,
and has been from the very start. When it comes to proper interpretation of
stats in science, geneticists are at the top of the hierarchy.

Your second point is far closer to what I think is going on, but I still think
that single-gene studies are the wrong way to go, as you might guess from my
username. They're testing for the wrong thing, single locus or single gene
causes, of a very complex phenotype with the involvement of many many
different loci and genes. So if there are 500-600 genes that are important,
maybe one passes the test in your particular subsample, but in a different
subsample the rest of the 500-600 genes mediate the effect. I.e. there's not
enough complexity in the model to account for the signal. What's worked very
well for simple diseases and traits may not work well for complex traits with
the influence of many many different genes.

~~~
btilly
_Multiple hypothesis testing is built into the design of the studies, and has
been from the very start. When it comes to proper interpretation of stats in
science, geneticists are at the top of the hierarchy._

It is built into the design of the studies. But studies that do not find
results do not get published. Thus there is a lot of room for exceptional
results to sneak through despite the attempts to get the stats right.

~~~
epistasis
GWAS studies are extremely expensive studies, often in the hundreds of
thousands of dollars in SNP chips alone, and will get published somewhere,
somehow. If they don't find results they get published in lesser journals,
because there's always _something_ to be said even if there are not
significant associations.

It's the same with academic clinical trials, even negative results get
published, because for those academics they still need something to show, and
a publication of a negative result is better than nothing.

Non-publication bias is more common in less expensive, more exploratory
settings, where there are lots of little experiments going on all the time.
This is quite different from GWAS.

------
samatman
Heritability is related to the degree to which a trait is genetically
determined. The relationship is far from trivial.

Skin color makes this much easier to understand. Imagine a couple, where the
man and the woman each have one Scandinavian parent and one Bantu parent.
Their children could have almost any skin shade.

If they have identical twins, those twins will have the same shade of skin.
Skin color is genetically determined but the heritability varies.

Imagine two people who have the same skin color as our first two, but they
come from an island population founded by Norwegians and Nigerians
exclusively. They are 20th generation, or 50th. Now, it is likely the skin
color of their children will be the same as their own.

Intelligence inherits upon many factors. Even identifying those factors proves
to be elusive and hard. The good evidence that intelligence is genetic is twin
studies: the good evidence that it is variable in heritability is every family
you've ever known.

------
gwern
Boring. The effect size of the variants is too small to find with n=10,000,
hence any positive findings are almost certainly false positives which will
fail to replicate. That's why the 3 SNPs found recently
([http://infoproc.blogspot.com/2013/05/first-gwas-hits-for-
cog...](http://infoproc.blogspot.com/2013/05/first-gwas-hits-for-cognitive-
ability.html)) were in a sample of n=101,000.

There's nothing here to undermine the view that genetics causes much of
variation in intelligence, it's just that the variation wasn't as clustered on
a few genes as people hoped because it would make the research so much easier.

------
pron
The now famous paper _Why Most Published Research Findings Are False_
([http://www.plosmedicine.org/article/info:doi/10.1371/journal...](http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.0020124))
singles out genetics as a field particularly prone to false positive findings.

------
tehwalrus
I would assume that many behaviours (including language itself) are inherited
- and yet have nothing whatever to do with genetics. How would you control for
this?

Only last week, we had an article on here about how vocabulary in very young
children was a function of how much parents talked to their children - with
marked differences between economic groups[1]. There are many many systematic
errors in this kind of data, and I have no good (ethical) suggestions in how
to eliminate them.

[1]
[https://news.ycombinator.com/item?id=6480155](https://news.ycombinator.com/item?id=6480155)

~~~
tokenadult
_How would you control for this?_

The classic way to control for cultural and in-family influences in studies of
human behavior genetics is to look for the rare cases of monozygotic
("identical") twins brought up in separate households after adoption. Those
studies of monozygotic twins reared apart (MZA twins) set a MAXIMUM figure for
the heritability of any trait of interest--because the genes are as similar as
they can be between two different human individuals, but the environments,
even in separate households, may not be as maximally different as they could
be in influence on the trait in question. There is a whole book about the most
famous study of identical twins reared apart, which took place at my alma
mater while I was an undergraduate and postgraduate student there (in other
subjects).

[http://www.hup.harvard.edu/catalog.php?isbn=9780674055469](http://www.hup.harvard.edu/catalog.php?isbn=9780674055469)

As some people will remember from the press reports at the time, the most
culturally variant upbringing two of the separated twins, Oskar and Jack,
studied by the Minnesota researchers received was one twin being raised as a
Jew, and the other twin being brought up in Nazi Germany and becoming a member
of the Hitler Youth.

[http://online.wsj.com/article/SB1000142405270230355210457743...](http://online.wsj.com/article/SB10001424052702303552104577436333754014866.html)

~~~
tehwalrus
I guess I was saying that the rarity of this happening in the real world makes
good statistics difficult (which are _essential_ in biological systems,) and
of course intervening to force better statistics is a rather horrific
proposition.

Thank you for the links though, I'll have a read!

------
tcskeptic
" _These and our other results, together with the failure of whole-genome
association studies of g to date, are consistent with general intelligence
being a highly polygenic trait on which common genetic variants individually
have only small effects._ "

This doesn't seem like a surprising result to me. What is being claimed is not
"intelligence is not genetic" but it is that "heritability of intelligence is
complex". For something that appears as complicated as human intelligence,
wouldn't this be expected?

~~~
scott_s
Things that are "expected" still need to be tested. Also,
[http://lesswrong.com/lw/im/hindsight_devalues_science/](http://lesswrong.com/lw/im/hindsight_devalues_science/).

------
JoeAltmaier
Nature vs nurture is hard to separate, especially when genes and culture tend
to be 'handed down' to the same individuals.

However I'm curious that they chose to use the very-powerfully-determined-by-
genes features of Alzheimers and BodyMassIndex as their control. Surely there
are other genetic traits that are not 'disorders' which could have been
referenced? Breakdowns in physical function would naturally have larger
measurable effects than, say, alcohol metabolism rates or whatever.

~~~
tokenadult
_Surely there are other genetic traits that are not 'disorders' which could
have been referenced?_

Studies of the issue of "missing heritability" have often investigated height
(bodily stature), which has a very high calculated heritability (resemblance
among close relatives) but which must be influenced by hundreds of genes, many
of very small effect. Even very extensive genome-wide association studies
(GWAS) in large samples find NO gene with large effect on height, and fail to
detect most of the presumed associations with height in gene associations
investigated in such studies.

The review article Johnson, W. (2010). Understanding the Genetics of
Intelligence: Can Height Help? Can Corn Oil?. Current Directions in
Psychological Science, 19(3), 177-182

[http://apsychoserver.psych.arizona.edu/JJBAReprints/PSYC621/...](http://apsychoserver.psych.arizona.edu/JJBAReprints/PSYC621/Johnson%20Current%20Directions%20Psych%20Science%202010%20\(G%20and%20E%20in%20IQ\).pdf)

looks at some famous genetic experiments to show how little is explained by
gene frequencies even in thoroughly studied populations defined by artificial
selection.

~~~
bayesianhorse
One example for the trouble with genetics in intelligence is the issue of
Malaria: If a child gets Malaria, it will have a lower intelligence quotient.
Resistance/resilience of Malaria sure has genetic factors. Would those factors
show up in genetic studies about intelligence? Betcha.

Should we accept this variance in IQ as genetic and unavoidable? Or should we
just buckle down, eradicate Malaria and stop worrying about these factors?

------
bayesianhorse
No surprise there...

Knowing a lot about genomic animal breeding made me wonder how people can be
so sure about genetic basis of intelligence, while we understand neither
intelligence nor the genetic basis behind it. For that matter, even plain body
height in humans is barely understood...

------
no_wave
Do we even have a working definition for intelligence at this point that can't
have holes poked in it from every direction?

~~~
Guvante
No. A unified definition may be impossible.

But not having a concrete definition doesn't make certain inferences
impossible.

------
stonewhite
Genes are to humans in the same way CPU instructions are to computers [1]. So
this experiment is analogous to measuring the capability /throughput of a
computer only by inspecting existence of arbitrary instruction sets. They may
be the atomic enabling factors, but can't really say much about something so
complex as intelligence.

[1]: Richard Dawkins

------
tocomment
Wouldn't intelligence be 100% genetic. I mean humans have intelligence and
insects have way less. And all that programming to make one or the other is
encoded in the DNA.

~~~
Symmetry
You could just as easily argue that it's 100% environment, since a human who
is never provided with food will end up dead, and therefore much less
intelligent than an insect.

------
thetruthhurts
"African Americans currently score lower than European Americans on
vocabulary, reading, and mathematics tests, as well as on tests that claim to
measure scholastic aptitude and intelligence. This gap appears before children
enter kindergarten (figure 1-1), and it persists into adulthood. It has
narrowed since 1970, but the typical American black still scores below 75
percent of American whites on most standardized tests. On some tests the
typical American black scores below more than 85 percent of whites"\-
[http://www.nytimes.com/books/first/j/jencks-
gap.html](http://www.nytimes.com/books/first/j/jencks-gap.html)

"Intellectual and personality measures were available from unwed mothers who
gave their children up for adoption at birth. The same or similar measures
have been obtained from 300 sets of adoptive parents and all of their adopted
and natural children in the Texas Adoption Project. The sample characteristics
are discussed in detail, and the basic findings for IQ are presented. Initial
analyses of the data on IQ suggest moderate heritabilities." \-
[http://www.ncbi.nlm.nih.gov/pubmed/496798](http://www.ncbi.nlm.nih.gov/pubmed/496798)

"Adolescents' IQ test scores were similar to those of their parents and
siblings only if they were biologically related. Our interpretation of these
results is that younger children are more influenced by differences among
their family environments than older adolescents, who are freer to seek their
own niches." \-
[http://www.ncbi.nlm.nih.gov/pubmed/6872626](http://www.ncbi.nlm.nih.gov/pubmed/6872626)

Notice how carefully worded the "interpretation" of that last one was. Rather
than suggest that genetics has to do with older adolescence not having IQ
scores that match their adoptive parents their "interpretation" is that the
adolescences simply chose not to perform as well as their adoptive
parents...Anything to avoid controversy.

White guilt is getting in the way of a lot of
racial/genetic/intelligence/violence studies. People don't want to go back to
a time when one group of humans were seen as superior and another inferior.
The funny part is, Intelligence wise, whites are NOT superior. Jews are..
Their intelligence levels are higher, achievement levels higher, hackers
should know this. Many of Silicon Valleys most prominent companies were
started by jews. Facebook, Craigslist, Google. Also a report by Joel Stein
from the New York Times showed that every major Hollywood studio was founded
by jews. In the fashion world: Ralph Lauren, Levi (Jeans), Guess, Mark Ecco,
Men's Warehouse, and most of the brands you see in stores today were also
started by jews.

"In 1921 Budapest, 88% of the members of the stock exchange and 91% of the
currency brokers were Jews, many of them ennobled. In interwar Hungary, more
than half and perhaps as much as 90 percent of Hungarian industry was owned or
operated by a few closely related Jewish banking families. Jews represented
one-fourth of all university students and 43% percent at Budapest
Technological University. In 1920, 60 percent of Hungarian doctors, 51 percent
of lawyers, 39 percent of all privately employed engineers and chemists, 34
percent of editors and journalists, and 29 percent of musicians identified
themselves as Jews by religion. Resentment of this Jewish trend of success was
widespread." \- Yuri Slezkine. The Jewish Century. Princeton, 2004. ISBN
0-691-11995-3

Since 1921 theres been a lot of catching up by Whites, Blacks, Asians, etc...
but Jews are still disproportionately successful and score high.

~~~
thetruthhurts
Continued: I think it's pretty obvious that genes have quiet a bit to do with
intelligence and achievement. There have been too many studies done on race
and iq, race and crime, race and achievement to just throw out. I'm not the
smartest but at least I'm living in reality. And I'm proud to see so many
HNers here doing the same and acknowledging the important role genetics has in
our lives. It's good to know there's more people following truth and science
no matter how blasphemous it may seem to a delusional emotion-oriented general
population hell bent on believing that everyone is "100% equal" in order to
feel good about themselves.

Nature is racist. Us finding out about it is not.

~~~
nether
It's only racist if you think the value of a person is tied to his
intelligence. Achievement is definitely related to intelligence, but I don't
think achievement makes one better than another.

