genetics

[Jake_Ellison]

Not my analogy. It would have to overwhelm the large amount of data to the contrary regarding genes as building blocks of our bodies and therefore our brains.

It's somebody's analogy. If there is such overwhelming evidence of the genes being the main factor in a person's intelligence, then that somebody wouldn't need that analogy to try and prove it. That person would present the evidence.

The logic that genes determine the development of children height-wise, therefor they probably do the same intelligence-wise, is fallacious. In fact, there's no logical relationship between the two. In fact, the analogy wouldn't even work with the development of big muscles, which are clearly the result of intensive training, and pretty much anyone can have big muscles if they train hard enough, for long enough. Why would it work for certain traits of the brain (left undetermined at this point in the discussion), that translate into higher intelligence? Maybe it's an analogy with muscle growth that works better. (from what I've heard, I would estimate that that's right, actually)

I am not sure why you think a link to brain size is significant.

That's good. The fact that you're sure I think that is not good though. I don't.

You're the one implying that a specific physical trait is responsible for intelligence. But you never named that trait. I submit to you that perhaps that trait(that set of traits and their relationships, actually) isn't fully known, and that the main reason why people are so ready to accept that genes are the main driving force behind intelligence is that they rely on analogies and intuitive thinking, not solid research, and that the functioning of the brain is nowhere near well enough known to jump to that conclusion. In fact, there's also a lot of evidence that brain development is heavily driven by experience and environmental cues. (not that it's even possible to tell someone's intelligence based solely on brain physiology, since no one knows exactly what to look for...but many people have an idea, and the verdict could go either way: smart people might be smart because their brain is developing a certain way, or people's brains might be developing a certain way because they are really smart, in other words because they are in the habit of using it the right way)

The clear progress average IQ levels have been making over the years, in the West, as well as various studies that show the changing environment (the Internet, games, technology) is changing the physiology of the brain, are all evidence to the latter, and against the theory that genes are the main factor in a person's intelligence level. I wouldn't claim that I have conclusive evidence, but I'd love to hear some evidence from you, to the contrary, instead of this analogy that is supposed to serve as evidence.

No, it is accepted because any belief to the contrary contradicts fundamental Epistemological principles.

That's rationalism.

Objectivists don't require reality to be a certain way, to not contradict their principles. Reality (including the way children are born) is a primary, and the way to know it is by studying it.

Epistemology is the way it is because of the way reality is (including the fact that children are born Tabula Rasa), not the other way around.

The fact that Objectivist Epistemology would not make sense if reality were different (or that it doesn't make sense to say that Tabula Rasa is not true, in the context of Objectivist Epistemology) doesn't change the relationship between the two: the facts cause the principles, the principles do not cause the fact.

Edited October 29, 2009 by Jake_Ellison

[~Sophia~]

I will break my responses because posts are getting too long.

It would have to suggest someway in which a process(evolution) which is essentially a process of variation would make some kind of exception for the human brain and make it static and identical to every other member of the species.

I can dig this up if you want but it has been found that the more advanced the brain is, the more slowly it's genes evolve. Genes expressed in human brains have been evolving at the slowest pace of all species.

However that fact does not mean that physiologically all human brains are identical or even close (and I certainly don't think so). The brain has the amazing ability to reorganize itself by forming new connections between brain cells and the environment in which a person lives (starting in the mother's womb), as well as the actions of that person (like learning), play a role in that plasticity.

Edited October 29, 2009 by ~Sophia~

[~Sophia~]

Undoubtedly, it's more complex, but I can't imagine any reason why the brain would operate differently then any other aspect of our bodies in terms of its relationship to a genetic code.

Normally, tissue-specific genes evolve faster than others because they have more limited effects (genes expressed only in male reproductive organs evolve very quickly, for example). On the other hand, if a gene affects processes in multiple organs, a mutation to that gene is more likely to be harmful to some action in the body. Thus, that gene will tend to change only a little over time.

But the researchers found just the opposite effect in brain genes. Genes expressed solely in the brain evolve more slowly than those expressed both in the brain and elsewhere in an organism, which in turn change more slowly than genes not associated with the brain at all. Mutations that disrupt existing interactions are selected against.

Edited October 29, 2009 by ~Sophia~

[aequalsa]

It's somebody's analogy. If there is such overwhelming evidence of the genes being the main factor in a person's intelligence, then that somebody wouldn't need that analogy to try and prove it. That person would present the evidence.

Listen Jake, I don't think we are having the same conversation. The "not my analogy" statement was referring to the fact that I did not present the analogy as "proof" of anything. Only to try to explain that our bodies(which includes our brains)...in some way...seem to be connected to our genes. If you don't believe that, then I have no more interest in trying to prove it to you then I would try to prove evolution to a creationist.

Beyond that, I never once said, implied, or suggested that genes were the main factor in a person's intelligence.

For whatever reason, the things you are writing have almost nothing in common with the content of my thoughts, so, rather then attempt to break down every single sentence you write and try to reexplain, I will politely excuse myself from continuing the discussion with you.

I'll only suggest that if you are interested in the subject, there is a great deal of information available, which seems to contradict what, I think, your current stand is. If you want particular book recommendations regarding some specific aspect I'd be happy to provide them.

[aequalsa]

I will break my responses because posts are getting too long.

I can dig this up if you want but it has been found that the more advanced the brain is, the more slowly it's genes evolve. Genes expressed in human brains have been evolving at the slowest pace of all species.

I would like to see that if possible. My main question would be whether or not it implies that there is no existent variation in brains or just that new mutations are less common.

[~Sophia~]

I would like to see that if possible. My main question would be whether or not it implies that there is no existent variation in brains or just that new mutations are less common.

Wang, Huan-Chieh Chien, Naoki Osada, Katsuyuki Hashimoto, Sumio Sugano, Takashi Gojobori, Chen-Kung Chou, Shih-Feng Tsai, Chung-I Wu, C.-K. James Shen. 2007. Rate of evolution in brain-expressed genes in humans. PlosBiology 5:335-342.

Mutations appear randomly throughout the genome. Mutations that disrupt existing interactions are selected against.

[aristotlejones]

Normally, tissue-specific genes evolve faster than others because they have more limited effects (genes expressed only in male reproductive organs evolve very quickly, for example).

Maybe this is why the prostate accounts for over 20% of male cancers. Too much bit crap.

<Φ>aj

[~Sophia~]

Y axis is IQ, X axis is Stimulation in the environment. There are 3 diagonal lines representing 3 similar responses to environment that children can have.

It is a hypothesis isn't it?

What assumptions were made in order to draw this graph? Are they valid? How can you measure stimulation in the environment? How do you assign a number for health and determine the slope of it's increase? I have seen many graphs looking very convincingly in the area of global warming which were based on nothing more than rationalism. Granted I have not seen it so I can't comment specifically. But it does sound to me like when it was concluded that a rocket could never reach Mars because the acceleration of Earth's gravity is too strong. To what degree was this graph based on actual measurement?

Edited October 29, 2009 by ~Sophia~

[~Sophia~]

Do you mean to say if ones phisiology causes them to get a pleasant buzz and someone else gets nauseous that this would have no impact on likelihood of alcoholism? If so, I disagree. It may have little impact on a first drink but the second is a different story.

It would have an impact for someone who makes their decisions based on what momentarily feels good. Is that the proper criteria of decision making for humans? (rhetorical question)

I don't view this as an embrace of genetic determinism.

If biology rather than their free choice is making some people behave immorally and even violate others rights then we can't hold them to the same moral standards. That would not be just. This is a serious issue, requires serious factual analysis, and demands a high standard of proof. It is important to critically examine whether or not the conclusions which are being drawn and reported in the media are valid.

People engage in discussions about possible prenatal screenings for "violence gene" and it is no such thing! (I really recommend that analysis I linked to).

I would view it as influential in the same way that what sorts of parents a child has can be influential in their development.

It is not the same type of influence and does not have the same implications.

Not statist....I said static.

Well supposedly being bilingual results in an increased number of neuronal connections .. but clearly that does not always translate to something tangible

Edited October 29, 2009 by ~Sophia~

[softwareNerd]

I'm not very well-read in the area of IQ and inheritance, but I have one fundamental problem with the reporting I read on this topic. Most boil down to something like this: try to see if IQ of genetically-close people (e.g. twins) are correlated if we factor-away the other influences. With this, the researchers will find a correlation that is indicative of IQ being heritable (say something fairly high, like 0.7). Though there are many objections to the outcomes and about such studies themselves, even if one ignores those, and assume they're right, my bigger problem is that this tells us nothing about the importance of genetics in real life.

In the "Gene Illusion" book, the author gives an example of myopia, which is inherited to a large extent. this would have been relevant some decades ago. However, in the real world of universal eye-tests for children, spectacles and lasix, the inheritability is something that is of little real-life importance 9except for an insurance company paying for healthcare).

Edited October 29, 2009 by softwareNerd

[aequalsa]

It is a hypothesis isn't it?

What assumptions were made in order to draw this graph? Are they valid? How can you measure stimulation in the environment? How do you assign a number for health and determine the slope of it's increase? I have seen many graphs looking very convincingly in the area of global warming which were based on nothing more than rationalism. Granted I have not seen it so I can't comment specifically. But it does sound to me like when it was concluded that a rocket could never reach Mars because the acceleration of Earth's gravity is too strong. To what degree was this graph based on actual measurement?

Sorry for the delay in response. Stupid life, always getting in the way of fun...

I read a few things I found regarding the study you posted. It is interesting that our brains evolution seems to have slowed significantly, but I am not sure it is relevant to the issue in the way I had hoped. Few new mutations does not mean that there is not currently a diversity existent within the population. The currently existing differences in brains is what I think may be a factor.

About the graph, I agree. There are all manner of difficulties in anything regarding human behavior because of the variability of action and the complexity of causation. A lot of the information comes from twin studies as well as studies during gestation, if I recall correctly. It shouldn't be terribly surprising though, that if a child is severely malnourished or unstimulated, especially during the early rapid pruning period period of life, his brain will develop poorly.

Just inductively though, imagine a fictional child raised to the age of 5 in an empty room. How well do you think his brain would form with nothing else to interact with? I would guess even with great care and inspiration later, he would have difficulty forming any complex thoughts or understandings. From this, I can see that a more stimulating environment would be more likely to allow for the kind of learning necessary to develop solid thinking skills. This lack of conceptual development is seen in many tribal communities where very few members ever achieve the capacity for formal operations. (piaget)

I have to go...Ill respond more later.

[~Sophia~]

Few new mutations does not mean that there is not currently a diversity existent within the population. The currently existing differences in brains is what I think may be a factor.

I did not mean to imply that there is no diversity. My point was that the variation is much lower and there seems to be some sort of evolutionary pressure to preserve, to keep the status quo, if you will.

It shouldn't be terribly surprising though, that if a child is severely malnourished or unstimulated, especially during the early rapid pruning period period of life, his brain will develop poorly.

Just inductively though, imagine a fictional child raised to the age of 5 in an empty room. How well do you think his brain would form with nothing else to interact with? I would guess even with great care and inspiration later, he would have difficulty forming any complex thoughts or understandings.

I absolutely agree. Perhaps I was not making my position clear enough so I will try to summarize.

There is a genetic component to mental abilities which sets an upper limit on what is possible. However, to even reach a half of that genetic potential the brain needs the right conditions. Conditions in the mothers womb, nutrition, and activities like learning all affect the development of the brain. I don't believe that we are at all equal in abilities, mental or otherwise. Equal environment (EE) assumption is often being used in behavioral studies and it serves a purpose to a limited degree but truly identical environment only exist for a limited time for monozygotic twins sharing the same placenta (which not all of them do - so it is important to look for that when you read those studies). After birth the environment is similar (because they share the same household) but NOT identical. Perhaps you could make the nutritional part quiet the same but then people vary, for example, in the level of focus and level of motivation toward learning. Also, it is at the protein level that most of what matters occurs. Diversity of other genes and again variation of environment affecting the function of these other genes create variation in physiological environment in which the products of brain genes function. As a result, no two brains develop the same and no two brains function in the same body conditions.

So eventhough there is a genetic component to mental abilities, a big chunk or even most of the observed variation is probably due to environmental differences (many of which are not in person's control btw - evironmental does not mean anybody can make themselves into anything). On a populaton level - perhaps some day we hit some optimal but the average intelligence measured has been increasing continuously almost since the moment the IQ test had been invented which suggest that that is not the case yet. When we do hit that "optimal environment" (perhaps when we learn more about what builds our brain in the most efficient way) - most of the differences observed in a population (assuming most will follow the recommendations) will be due to genetic variation.

In the name of disclosure, another possible explanation for seeing the shift would be that IQ tests measure something more tied to knowledge than raw mental ability. Since the level of education is increasing on average - people would do better on those test on average.

Now there are of course exceptions of very high ability (something went very right - like Rands) and very low (some disfunction) but both of these are relatively infrequent and the first seems to be a random occurance, arising even in less developed populations. There IS some variation due to genetics but I definatly don't think most of the observed variation is due to genetics. Not yet.

Edited October 30, 2009 by ~Sophia~

[~Sophia~]

Though there are many objections to the outcomes and about such studies themselves, even if one ignores those, and assume they're right, my bigger problem is that this tells us nothing about the importance of genetics in real life.

Do you mean in reference to IQ or in general?

[softwareNerd]

Do you mean in reference to IQ or in general?

No, I meant this only about IQ. I suppose it is true for other areas too, if it can lead to answering a question: one whom should be focus a certain corrective action, or on whom will a certain action work. Edited October 30, 2009 by softwareNerd

[~Sophia~]

A lot of the information comes from twin studies...

The twin method is an environmentally confounded research technique unable to disentangle possible genetic and environmental factors. For an answer of why that is I recommend the book softwarenerd mentioned "The Gene Illusion" by Jay Joseph. He made a case that this method only offers what he called "an initial hint" that a trait difference may have a genetic component and nothing more. There is more to this book and I think it is a must read for those interested in this subject and going into a relevant profession.

[aequalsa]

No, I meant this only about IQ. I suppose it is true for other areas too, if it can lead to answering a question: one whom should be focus a certain corrective action, or on whom will a certain action work.

I'm not certain that I totally understand your question, but the relevance that heritibility has for me is in pedagogy. If some individuals have innate capacities and detriments, then different approaches to education will be more or less effective. The debate, as I understand it is whether IQ is 40% or 80% heritable. If it is 80% heritable, then the most important thing a child needs to develop his or her highest capacity is a well rounded diet. 40% leaves a lot more room for environmental and scholastic failure.

Outside of that, mate selection, reasonable expectations for your children and other people in general, self-analysis(such as determining your own strengths and weakness to help determine what you ought to pursue, are a few that come to mind.

On a side note, one of the more interesting things about the twin studies is that MZ twins raised apart usually had more similarities, generally, then MZ twins raised together because they don't try to differentiate themselves. I liked that the choice to forge their own independence in this unsual circumstance over powers genetic and environmental similarities.

[softwareNerd]

I'm not certain that I totally understand your question, but the relevance that heritibility has for me is in pedagogy.

To the extent that they focus on the extent of heredity, I don't see how any of the twin studies and so on provide information that is helpful in pedagogy. If that were the objective, the money would be better spent studying the effectiveness of various environmental factors, since those are under our control. Think of people with myopia. By studying the detailed nature of their problem, one can devise ways to tackle it; consequently, extent to which myopia is hereditary is not of much real world value -- even less so in an age of soft-contacts and lasix surgery.

I see the heredity research as analogous to trying to understand if myopia is mostly heredity versus (say) the result of bad reading angles, poor lighting, late starts at reading, etc. Even this would be understandable if the focus was on the environmental factors. However, randomizing for environmental factors, to measure the impact of heredity given an equality of environmental factors seems to be of little relevance. One could find pretty high correlations, and yet there is absolutely no implication that some simple environmental technique would not fix the problem.

[aequalsa]

I did not mean to imply that there is no diversity. My point was that the variation is much lower and there seems to be some sort of evolutionary pressure to preserve, to keep the status quo, if you will.

I absolutely agree. Perhaps I was not making my position clear enough so I will try to summarize.

...

Now there are of course exceptions of very high ability (something went very right - like Rands) and very low (some disfunction) but both of these are relatively infrequent and the first seems to be a random occurance, arising even in less developed populations. There IS some variation due to genetics but I definatly don't think most of the observed variation is due to genetics. Not yet.

Thanks for the clarification.

I understand that environmental factors affect gene expression. That doesn't change the fact though, that the genes must be present to be affected.

Do I understand you correctly to be saying that all of the genes that encode for the proteins and structure of the human brain, are so conserved that there is no significant variation between individuals? If so, I would find that to be very surprising because that is completely at odds with the significant variation between male and female, and even homosexual brain structures.

So eventhough there is a genetic component to mental abilities, a big chunk or even most of the observed variation is probably due to environmental differences (many of which are not in person's control btw - evironmental does not mean anybody can make themselves into anything).

I don't understand how you come to this conclusion, that most observed variation can be reduced to environmental difference. Most studies conclude 40%-80% heritability with IQ, but the very idea of assuming a percentage bothers me.

If you take some minor genetic variation in a little girl; say she has several genes that make for a symmetrical, even toned, face with pleasant, averaged features. This, in the real world, is called "pretty" and leads to very different reactions from everyone she comes across with a great deal of positive feedback for looks compared to a less attractive girl. So a feedback loop is instigated by the gene which results in her pursuing her attractiveness through the use of makeup, exercise, and dress, ultimately landing her a job in the modeling industry. It's obvious to me that genetics, environment, and decisions she made all had a part in that ultimate destination since, if any one was removed, it would have had a drastically different outcome. What I don't see is a way to ascribe, with any certainty, a percentage of affect. They are three parts that interact with each other to create great variation but claiming one is more or less important doesn't seem substantially to me currently.

The only way for a brain to be exempt from this is if there was no significant genetic variability. I would guess that the very small differences in genes could significantly affect mylenization or cell density, for example.

I take your point about conservation though. It makes sense that there would be a good deal of it in regard to an essential protein like hemoglobin, for example. I would just be surprised to find that of the 100s(or 1000s?) of genes that encode for the proteins and structure of the brain, that there is no significant variation.

I also had a question about the article you sent earlier. (thanks for your patience with a not-geneticist) In the version I found, it stated in regard to humans

(i) faster evolution in gene expression, and (ii) a likely slowdown in the evolution of protein sequences.

If there is a fast evolution in expression-say for example, an increase in the level of dendrite mylenization- this could have an enormous impact on intelligence even if protein sequences were identical and completely static. Is this a correct characterization?

[softwareNerd]

Most studies conclude 40%-80% heritability with IQ, but the very idea of assuming a percentage bothers me.

From what I understand, saying that a trait is 70% heritable does not mean that 70% of it is attributable to inheritance. Rather, it means that 70% of it is attributable to inheritance, other factors remaining equal. So, this is not about 70% heredity vs. 30% others. Instead, what it means is that if you kept other factors the same, then heredity itself could predict 70% of the observed variation. Therefore, a trait can be 70% heritable and yet inheritance can be one of the least important aspects.

[~Sophia~]

I will split my answer again.

I understand that environmental factors affect gene expression. That doesn't change the fact though, that the genes must be present to be affected.

I am not sure if I understand what you mean here. We all have a complete set.

Do I understand you correctly to be saying that all of the genes that encode for the proteins and structure of the human brain, are so conserved that there is no significant variation between individuals?

I will quote a conclusion of a PhD theses from 2007 which looked at dopamine and serotonin genes across human worldwide populations : "In general we found less genetic differentiation based on allele frequencies and measured by the FST value in this set of ‘Brain genes’ than in other large gene sets for distinct gene classes, indicating that this set of dopamine and serotonin genes is more conserved across worldwide populations than expected."

We don't know enough to assign significance to the degree to which you have indicated above. But it has been increasingly suggested that advanced brains are driven primarily by the increasing complexity in the network of gene interactions and not complexity of genes themselves.

If there is a fast evolution in expression-say for example, an increase in the level of dendrite mylenization- this could have an enormous impact on intelligence even if protein sequences were identical and completely static. Is this a correct characterization?

Yes.

If you ask what affects expression levels of genes: genetic, epigenetic, and environmental factors. This is a very hot area of study right now.

Edited October 31, 2009 by ~Sophia~

[aequalsa]

From what I understand, saying that a trait is 70% heritable does not mean that 70% of it is attributable to inheritance. Rather, it means that 70% of it is attributable to inheritance, other factors remaining equal. So, this is not about 70% heredity vs. 30% others. Instead, what it means is that if you kept other factors the same, then heredity itself could predict 70% of the observed variation. Therefore, a trait can be 70% heritable and yet inheritance can be one of the least important aspects.

I think I understand what you are saying, but I am disagreeing with the whole idea. All things being equal, we could have one child that maxes out at an IQ of 80 and another that maxes out at 165. If we remove 40% of the genius' frontal lobe, maybe it drops to 45. This doesn't imply to me that the environment is in any way "more important." I don't think that either of them are rightly considered more important.

I see it as some strange valuation like deciding what part of a car is more important. The wheels? The motor? Fuel line? I see it as sort of pointless to ask, since the car won't get anywhere without any of those parts. I suppose that one could argue that genes are like the ashtray or trunk and not critical to the brains development at all. I would disagree but it could be argued.

[~Sophia~]

So a feedback loop is instigated by the gene which results in her pursuing her attractiveness through the use of makeup, exercise, and dress, ultimately landing her a job in the modeling industry. It's obvious to me that genetics, environment, and decisions she made all had a part in that ultimate destination

Here is a very good article relating to feedback loop hypothesis in relation to IQ. This however does not imply that this is a necessary path/sequence of events for anyone to reach the same destination. It is one of the possible mechanisms.

since, if any one was removed, it would have had a drastically different outcome.

For this girl maybe. Another much less attractive girl may happen to be very motivated and driven toward similar goal despite the lack of positive environmental feedback. She is the independent type with a positive self esteem. She does the diet and exercise part plus she carefully and with a great attention to detail examines the requirements of the job and becomes more skilled at posing and facial expressions in front of the camera. She looks "interesting". People proclaim: camera loves her.

What I don't see is a way to ascribe, with any certainty, a percentage of affect. They are three parts that interact with each other to create great variation but claiming one is more or less important doesn't seem substantially to me currently.

You moved a bit closer to the middle. I also don't deny the significance of both. In fact, I was defending the biological side some months ago. As I mentioned I don't think anyone can make themselves into anything. It depends on the individual context - context which is not only set by genetics but still often not within one's conscious choice. I don't have a rule - it has to be judged on individual bases.

[~Sophia~]

As a side note...

Purely on a genetic side, a biological child may not be as intelligent as his parents.

In the production of a sperm or an egg half of what made you exactly the way you are genetically is discarded and then those two random halves from each person fuse. It is more about what is in the family gene pool than the specific genetic makeup of the parents (which makes their abilities unique - perhaps quiet different from their known ancestors). Also, what happens to each parent's genes and bodies during their life has no genetic influence on their child because that part of germ-plasm which makes up a gamete remains unchanged during our lifespan (germ-plasm is being kept separate from the body).

We are genetic descendents not from our mother but from her ovaries. It is more about what is in the two families gene pool. Same way a child maybe much more intelligent than his parents.

[aequalsa]

To the extent that they focus on the extent of heredity, I don't see how any of the twin studies and so on provide information that is helpful in pedagogy. If that were the objective, the money would be better spent studying the effectiveness of various environmental factors, since those are under our control. Think of people with myopia. By studying the detailed nature of their problem, one can devise ways to tackle it; consequently, extent to which myopia is hereditary is not of much real world value -- even less so in an age of soft-contacts and lasix surgery.

I see the heredity research as analogous to trying to understand if myopia is mostly heredity versus (say) the result of bad reading angles, poor lighting, late starts at reading, etc. Even this would be understandable if the focus was on the environmental factors. However, randomizing for environmental factors, to measure the impact of heredity given an equality of environmental factors seems to be of little relevance. One could find pretty high correlations, and yet there is absolutely no implication that some simple environmental technique would not fix the problem.

I see. In terms of pedagogy, if different genetically based temperaments like those I referred to above, exist, then different educational techniques would be necessary. A truly gifted child might be held back by too much stimulation since they are (probably) forming more principles out of fewer examples. A slower child might be benefited by a more traditional approach with a great deal of oversight and nearly continual prodding. This bears out somewhat in education where some children do not do well in a self-directed Montessori system but will thrive in a Prussian, discipline based system. If the child's temperament and proclivities can be identified early, educational decisions could be made more appropriately.

If we are to assume that all brains are essentially identical from the beginning, and they are not, then we would run the risk of trying to squeeze square children into round holes.

[aequalsa]

Here is a very good article relating to feedback loop hypothesis in relation to IQ. This however does not imply that this is a necessary path/sequence of events for anyone to reach the same destination. It is one of the possible mechanisms.

I browsed through it. Is there some point in particular that you wanted me to take note of?

For this girl maybe. Another much less attractive girl may happen to be very motivated and driven toward similar goal despite the lack of positive environmental feedback. She is the independent type with a positive self esteem. She does the diet and exercise part plus she carefully and with a great attention to detail examines the requirements of the job and becomes more skilled at posing and facial expressions in front of the camera. She looks "interesting". People proclaim: camera loves her.

Sure, that could happen, but my point is that this modeling career would be much less likely, since she's ugly. To suggest that people tend toward the sorts of activities which they are worst at contradicts most of my experiences.

You moved a bit closer to the middle. I also don't deny the significance of both. In fact, I was defending the biological side some months ago. As I mentioned I don't think anyone can make themselves into anything. It depends on the individual context - context which is not only set by genetics but still often not within one's conscious choice. I don't have a rule - it has to be judged on individual bases.

I really don't think that I did. I have been accused in this thread, several times, of saying that genes were more or most important in the IQ of an individual. I have never meant to say that, I don't remember saying that, and if anything I wrote is construed as that, then I apologize. My point from the beginning was that the nature/nurture dichotomy is a moot argument. The epigenetic theory of development that I keep mentioning, is what I am advocating as the most probable answer to this relationship. basically, it's the idea that genes and the influence of the environment over time on the expression of those genes and the environment in general, shape the actual capacities of the child and eventually the adult.