kjmtchl,

According to Standford Encyclopedia of Philosophy the consensus among philosophers of science (POS) is in agreement with you — an ignominious distinction in my opinion :

“There is something of a consensus in most fields (e.g. philosophy of biology, evolutionary biology, psychology and behavioral genetics) that heritability measures (particularly hb2 measures) only have a very limited use. The consensus among philosophers of biology is that broad heritability measures are uninformative but there are a few dissenting voices (e.g. Sesardic 1993 and 2005) (Heritability)

I guess I am of Sesardic’s mind in this matter.

When it comes to heritability estimates there are two important questions related to the issue of “innateness”: “Does broad heritability imply genetic causation?” and “Does high heritability imply environmental immalleability (give the range of environment prevalent during the time the estimates where made)?” The answer to these is dependent on whether the heritability estimates are “confounded” by gene-envrionement interactions and/or correlations. To the extent they are not, exact percentages are very informative. You can see an illustration of this here: http://www.scribd.com/doc/62132318/15/Lost-in-correlations-Direct-and-indirect-genetic-causes (Table 5.4 p.174, from Sesardic, Making Sense of Heritability.)

Now, you are making the case that the estimates (frequently?) are:

“The evidence on both sides is very strong. In general, for traits like intelligence and personality characteristics such as extraversion, neuroticism or conscientiousness, among many others, the findings from genetic studies are remarkably consistent…. I would argue that the effect of experience-dependent development is typically exactly the opposite….Our environment does not just shape us – we shape it.”

Here, you are referring to (active) GE correlations. Now my points would be:

1) Traits need to be evaluated on a one by one basis to determine the extent to which the genetic variance is independent of environmental variance. In the case of some traits, like IQ, the evidence suggests that the variance is mostly additive and therefore not a function of environmental amplification of the sort you seem to be thinking of.

2) Heritability estimates can be semi-informative as to the nature of possible GE correlations, since for there to be such correlations, genes need to be correlated with the environment. So, for example, if the shared environmental component (C) of an estimate is zero, as it is in the case of many traits, you can rule out, a priori, GE(c) correlations.

3) Even if there are significant GE interactions and correlations, you can still make probabilistic causal accounts of the effects of genes — see my reference to Tal (2011) – which then allows for a quantification of the effects of environmental modifications (again, given the range of environment prevalent during the time that the estimates where made.)

So, as I see it, heritability estimates are at least semi-informative in regards to the question of malleability.

Environment provides a much more readily predictable set of data than genes do. When dealing with genetics the variables increase. Which is why I feel when it comes to looking at individuals and helping them, much more productivity could come from observing how their environment effects them.

For instance, I believe that a human will never reach self actualization (total self responsibility, independence, rationality) when they are subjected to hierarchical power structures that impede individuation.

You speak of ‘intervening’ in the cycle, but that also implies that a child must be subjected to interference in their development. This reminds me of the dangers of genetics in general, that we will begin to ‘intervene’ to try and cure people of maladies we find genetic. But the ‘intervention’ simply reinforces power dynamics, the implications that adults know what is best for children and no matter how much they protest there are objective goals we need to achieve through manipulation.

Before we do anything, I believe, it would benefit humankind to stop intervening in individual’s lives, children included. Instead of expecting kids to alter themselves to fit our needs (‘why won’t my child listen to me?!’) why not look in the mirror and ask ourselves if we can admit that we are no less fallible. Maybe then we can provide safe environments for our kids to explore, but not tell them how to explore it.

Also, no one is “blaming” the genes and certainly not blaming the individuals for carrying some particular genetic variants – I am not saying that “an autistic simply brings out the autism in themselves by reinforcing their own behaviors in the school yard”. That makes it sound like they are choosing to be autistic, which is absurd and not the point I am trying to make at all. The point is to recognise the effects that genetic variants can have on risk for disorders like autism or dyslexia (or ADHD, schizophrenia, etc.) or on general personality traits and also recognise the effects that a person’s innate tendencies can have on their experience. This will hopefully allow intervention to short-circuit this vicious cycle.

Another example: low value mates, physically unnatrtactive people, can suffer from depression or be very confident. I have observed this. Many European women I meet who are not particularly attractive still have confidence. They grew up in good homes with nice parents who instilled confidence in them. Contrast that with many American women I meet who have unspectacular physical features. They starve themselves, the get tons of plastic surgery.

If Autism is genetic and an autistic simply brings out the autism in themselves by reinforcing their own behaviors in the school yard, who’s to say a depressive does not follow the same pattern? Again we have a scenario where we blame the individual, which always is so much easier than looking at environment.

This is the slippery slope I speak of. If you blame genes for autism, why not A.D.D.? Then all of a sudden shoddy schooling is not a problem so much. Kids are the problem. We don;t feel as compelled to alter our behavior to create a better environment for young children, but instead begin to look for ways to alter the children to accomodate the environment that we create, thus reinforcing power structures that favor adult agendas.

In hunter gatherer societies, none of these problems really existed. Psychopathologies and developmental disorders were not a pressing issue. But the adults did not force the children to adhere to schedules, do monotonous work, live outside of a close nit tribal atmosphere (kids are so very isolated these days.)

i will always take issue with any scientist’s attempt to predict behavioral patterns based on genes in any reliable manner. Environmental stimuli provide much more precise observational patterns than genes ever will in the foreseeable future.

I reason that despite our ability to map the genome, and even make such bold statements as we have found the cancer gene or the gay gene or the violence gene, no single gene will ever prove responsible to 100% of any human behavior or psychology.

You obviously lean more towards genetics, and seem to believe that genetics plays a more important role in human development. Personally I lean more towards environment. Even if the influence was a perfect 50/50 balance between the two, environment will always provide data that makes itself much more easily observable and quantifiable.

I am personally on the autistic spectrum, and I have (adopted) cousins who are as well. My family has never been stable and both my cousins and i grew up in chaotic households. If genes play a significant role in our predisposition for autism, then the environments we lived in catalyzed that predisposition. Autistics hate disorder and chaos in their lives. They like stability. The parents failed to procide that stability. Yet I see plenty of healthy, self actualized individuals who grew up in stable, loving home environments. So to me it seems obvious, my environment created me.

You are ascribing opinions to me that I have not stated and do not hold. I try not to insinuate anything – I try to mean precisely what I say. For example, I said “Our environment does not just shape us – we shape it”. Note the word “just” in that sentence – it is included for a reason. I do not as you claim say the environment has no effect on us. Quite the opposite in fact – I tried to make it very clear that brain development involves an intimate interaction with the environment and our patterns of experience. The point of the post is that our innate preferences will tend to shape that experience. Again, I use the phrase “tend to” very deliberately, to (try to) make sure that anyone who reads the post carefully will realise I am NOT excluding environmental effects! And I also specifically do not refer to extreme environmental factors or experiences like neglect or abuse _ I absolutely agree that these can have very large effects. You are arguing against positions that you only imagine I hold.

“On the one hand, behavioural genetic studies show that many human psychological traits are strongly heritable and thus likely determined, at least in part, by innate biological differences. On the other, it is very clear that even the adult brain is highly plastic and changes itself in response to experience. ”

Then you hypothesize that:

“The reason is that our innate tendencies shape the experiences we have, leading us to select ones that tend instead to reinforce or even amplify these tendencies. Our environment does not just shape us – we shape it.”

No exceptions, no nod to environmental effects. We just shape our environment.

So abused people simply seek out abuse because they were born with genes that cause them to victimize themselves? Seems the insinuation.

“A child who is naturally shy – due to innate differences in the brain circuits mediating social behaviour, general anxiety, risk-aversion and other parameters – will tend to have less varied and less intense social experience.”

Your hypothesis disregards parenting style?

Autism and dyslexia are very specific. But you seem to imply that all behavior and emotion are simply genetically determined.

Statistically an abused child is FAR more likely to abuse than a non abused child. Genetic brain differences?

Blaming behavior on genes shirks personal responsibility and starts a slippery slope to eugenic minded policies.

Arguments of genetic determinism will never be able to rule out variables. The most resilient of soldiers will come down with a case of shell shock in the trenches. A violent, abusive culture will propagate individuals who fail to achieve self actualization.

all this argument for nature reminds me of blame the victim.

Calculating exactly what the percentages are in various populations doesn’t really help much – they are always going to be very rough estimates anyway. What I was trying to do here was show that experience can be affected by genetics, in individuals, in ways that tend to amplify initial differences. Whether such an effect can be discerned in mathematical estimates of heritability is another matter and it doesn’t bear on whether the effect actually happens – it depends on the design of the study.

I imagine that you don’t spend any time trying to partition variance, so what you mean is that it’s a waste of time for others to do so. Why would the population specific nature of heritability estimates make them worthless? Surely such estimates narrow the search for the cause of variance and point which way to look. Anyways, you might be interested in the following paper: Tal (2011) “The Impact of Gene–Environment Interaction and Correlation on the Interpretation of Heritability.” It goes some way in (conceptually) clearing up the nature/nature x nurture debate. (Doesn’t our discussing nature/nature x nurture instead of nature/nurture, say something about the utility of heritability estimates?)

In baseball, the ideal background for being a manager is believed to have been a marginally talented major leaguer at a difficult position: a journeyman catcher or utility infielder.

Does the SAT-M tap into a largely immutable ‘g’ or is it more of a skills measure from that vantage point?

http://psycnet.apa.org/journals/edu/82/4/866/

ben g,

IQ is correlated with genes, brain volume, behavior, and the environment. An innatist model would say: genes –> brain volume –> IQ –> behavior –> environment. An rGE model would say: genes –> behavior –> environment … or something along those lines with the environment mediating the relationship between genes and IQ/brain volume. One way to test the rGE model is to decompose the variance for IQ and brain volume and then look at the covariation. See the logic in Betjemann et al. “Genetic Covariation Between Brain Volumes and IQ, Reading Performance, and Processing Speed” or Leewenn et al “A genetic analysis of brain volumes and IQ in children.”

I didn’t know multivariate analyses could check for rGE.. I thought they partitioned the variance between traits into the ACE model.. Could you link to a study were they check for rGE and don’t find it?

Let’s not forget that differences in brain plasticity themselves are partially under genetic control. As for rGE explanations for variance in traits like IQ, I don’t by them. Why aren’t GE correlations detected by multivariate analysis?