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Genetics and intelligence, is your intelligence determined from birth?

  1. Jan 28, 2014 #1
    This is a fairly taboo and controversial field. I've been hearing from many studies on intelligence, that it is highly heritable. Identical twins raised independent of each other have around a 0.75 relation in IQ tests. Siblings raised together have a .45 relation. What makes it worse is that people below a certain IQ in physics/math majors don't stand a chance. Is intelligence really set in stone, and determined from your birth? I'm inclined to think so, but I think there is still more to the picture that we still don't know.

    What about neuroplasticity? Is it not the case that the human brain evolved in order learn and to solve complex problems, which could reshape itself, which was vital for our survival? Then why is IQ so heritable? Is it because small differences in genes can cause a huge IQ gap in different people over time? I don't think anyone has thought of this, but what if our genes only determine what sort of stimulation we like, thus effecting our intelligence? For example: There are two boys, both aged 10, their names are Peter and Bob. Peter likes collecting sticks, he is infatuated by them, but Bob is interested in solving maths problems, he is also infatuated by what he does. So, since Peter's hobby isn't very intellectually taxing, he won't develop the mental skills in order to be a mathematician, thus he may end up with a low IQ. Bob on the other hand is seeking out difficult stimulus, and will probably end up with a high IQ. So what if what we seek to stimulate ourselves with, is what determines our IQ, not genetics themselves? What if genetics merely makes us more inclined to seek out one thing instead of another, which explains the correlation with IQ and genetics.

    I'll set up a causal link here:
    x = how intellectual taxing what a person seeks to stimulate themselves with.

    IQ = x
    IQ =/= genetics
    x = genetics

    So IQ does not equal genetics, but x = genetics. So what I'm saying is genetics indirectly effects intelligence, it's not a direct causal relationship between them like what I've been hearing. Like in formal logic, correlation does not = causation, it could be a whole other factor like I've said here. So, if it is the case that genetics determines what we are inclined to stimulate ourselves with (instead of genetics directly effecting intelligence), can someone which has a low IQ, change their IQ if they were to focus on doing maths or high level thinking activities?

    I really do hope that genetics doesn't determine IQ to a large degree (because IQ and academic ability are closely linked), because I'm going to university this year doing computer science, and it will be horrible to find out if there is some sort of genetic predisposition I have that will stop me from getting decent grades. I had a mixed track record in high school (went well in some subjects, bad in others), mostly because of poor study habits, which I am looking to change.
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  3. Jan 28, 2014 #2


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    Well, I will ask you something. Is an Idiot-Savant an idiot or a savant?

    Does IQ represent general intelligence, and can it be carried over to specific subjects.
  4. Jan 28, 2014 #3


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    In psychology, there's something called the 50-0-50 rule and is thought to apply to both intelligence and personality (specifically, the "big five" traits). Some people differentiate intelligence as more of a 75-0-25 split.

    Anyway, the three categories are: genetically inherited - parental social influence - peer social influence.
  5. Jan 28, 2014 #4


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    There are 600 genes known to cause intellectual disability, that's probably only the tip of an iceberg, many more are expected to emerge. While intellectual disability is defined as an IQ below 70, one can imagine that less harmful mutations could have a more moderate effect on IQ and segregate within families. However, the brain is really plastic, so with good stimulation one can boost ones performance: use it or lose it.
  6. Jan 28, 2014 #5

    Judging by their ages I would think it's likely that some part of intelligence is linked to genes. You're either born a genius or you're not... I don't think someone can become a genius. One boy Arran Fernandez, born in England sat GCSE mathematics at age 5 and got an A* and considering the test is designed for 16 year olds... At age 11 he was accepted into Cambridge University and at age 16 completed his PhD in Mathematics.

    I think everyone has potential to learn, but you're either born a genius or you're not in my opinion.
  7. Jan 28, 2014 #6
    Have you considered that those children were exposed to high level mathematics at a young age? I'm pretty sure mathematics isn't something you're born with. You have to learn the relationships between x/y and the gradient line in calculus, no one is just born with the ability to do it. Einstein too was exposed to differential calculus at a young age, because he was the one to seek it out, he became very good at it. There is no reason why any child that seeks out high level maths at such a young age shouldn't be completing their PhD in maths at 16. It's pretty much a given. Especially if they like it, they'd be hugely more likely to retain what they are learning.

    If I liked maths more than I did video games (and spent the same time on maths as playing games), I would at least be incredibly good at high level maths, at most be completing a PhD at 16. But this can be said about almost anyone. The thing is, most people don't like maths (including me), so it's not too surprising you don't see very many prodigies at math. I think it's because math is a very dry theoretical subject, which seems to have very little impact on our everyday lives (unless you are an engineer or physicist, it matters quite alot). So yes, they probably are born with it... Well, not the ability to do math, but the love of it. I'm decent at math, definitely not a prodigy, but I do get by better than a decent portion of the population. I never learnt to properly re-arrange an equation until physics in grade 12, because I liked physics. Before that I never paid attention in math classes, since it was such a bore to me. Personally, nothing excites me about math. Now think of all the people that have the capability of being what would be called a 'prodigy', but do not use it because they find the subject a bore? The only people that I don't think would have the capabilities are people with actual mental handicaps. Other than that, I see no reason why someone couldn't excel at something like maths if they were exposed to it at a young age, had parents that supported their activities, and liked doing it.

    Also, why are we talking about opinion? What about fact? Is there a basis in neuroscience to say such a thing?
    Last edited: Jan 28, 2014
  8. Jan 29, 2014 #7


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    Do you have anything to back that statement up?

    What you have stated is merely supposition.
    Are you using the word "like" in a colloquial sense, or definitive.
    If someone has difficulty with a subject, they might not "like" that they have a difficulty, but that does not automatically transfer to them not "liking" the subject.
  9. Jan 29, 2014 #8
    I wasn't making an overarching universal truth claim that most people do not enjoy math. But from my experience of being a student, no one really enjoyed math. It does not follow from someone having difficulty with a subject, that they don't like it, so I agree with you. There are many reasons why people may not like math, and that is a purely subjective basis, really. Just as how some people really like math. I personally do not enjoy doing maths because much of it was extremely dry in high school, and the exercises we did seem to have no practical relevance. And it's not that I find it overly difficult, crunching numbers just isn't enjoyable to me. I could do it, but I never enjoyed it. I think I also dislike the fact it restricts how you think, to a step by step process. The only thing that really interested me in math was fractals, because they can be so wild, yet ordered. I guess more imaginative people don't enjoy math as much.
  10. Jan 29, 2014 #9
    I have tutored many people, including my own kids, in math and related topics. There is a huge variation in peoples ability to absorb math. I remember when I was a kid in the 6th grade. The teacher would hint at the next Algebra topic an I had it - while the rest of the class struggled for two weeks before the next topic was introduced. My son is the same way. My daughter is good, but not that good. In both cases, I tried to introduce these topics to them when they were in the fourth grade - to no effect. They just weren't ready.
    To a large degree, math is something you're born with. It's symbol processing, a variation of language processing. When I present a logical deduction, some people immediately recognize what I am doing and can "fill in the blanks" even before I provided full details. Others recognize it in a different way - as some sort of alien exercise. They can follow it at a semantic level, but if you revisit it the next day, they're back to square one.

    The brain clearly is "plastic", but there are limits. With training and practice, you can learn to recognize wetland plants in a winter scene - or, as a radiologist, learn to interpret the fine points of xray and MRI images. But if you're congenitally blind, you can't learn to see.

    Also, the brain does not fill out its genotype until a person is in their late twenties. So it's hard to judge when a person should give up on specific subject matter.
  11. Jan 29, 2014 #10
    Obviously I'm not stating that some kids are born with the knowledge of algebra but they're born in such a way that once they learn it, it comes to them naturally. The same applies for art, music ect. You can learn to compose music or paint a fantastic painting but what about the natural born artists or composers like Mozart and picasso?

    Some people have the ability to pick up a brush and paint, the look at an equation and answer it. I don't know but I really think that you're born with an certain level of natural ability.
  12. Jan 30, 2014 #11
    Mozart was being taught piano and composition from a young age (him parents also taught him), and same with Picasso, his first word was 'pencil' (but in a different language of coarse). Time and time again, I see artistic and musical talent gained through years of experience. I don't think painting or musical ability is something you are born with.

    So it's not too surprising to see children brought up doing art and music, and becoming good at it.
  13. Jan 30, 2014 #12
    I'm still not totally convinced that is the case that the differences in their ability to pick up things like math is largely genetic, and their in built intelligence. Could it be the case that some people find it hard to pick up math simply because they dislike it? If you like something, dopamine
    is being released (dopamine is vital for learning) and the person is able to pick it up much easier. It's going to be harder to teach someone who hates math more than anything in the world, than someone who loves it, I think that's the same with any subject though.

    And you said that people can follow it at a semantic level, but the next day they are back to square one, but isn't that what maths is about? Following a few semantic steps in order to find the answer to something? For example, to find x in y - 1 = x, you just add y to both sides to cancel it out. Then you just have to remember how that works. If someone cannot remember it, it may be a problem with their memory, more than their ability.
  14. Jan 30, 2014 #13
    The influence of shared environment was small for both aptitude and talent. Additive and non-additive genetic effects explained the major part of the substantial familial clustering in the aptitude measures with heritability estimates ranging between .32 and .71. Heritability estimates for talents were higher and ranged between .50 and .92. In general, the genetic architecture for aptitude and talent was similar in men and women. Genetic factors contribute to a large extent to variation in aptitude and talent across different domains of intellectual, creative, and sports abilities.

    Much less is known about the genetics of the high end of the distribution. Finding heritability in the normal range of cognitive ability does not imply that high ability is also genetic in origin. However, the first twin study of high IQ children, which uses a new technique that analyses the average difference between extreme groups and the rest of the population, suggests that high IQ is as heritable as individual differences in the normal range. We are currently engaged in a molecular genetic study that attempts to identify specific genes that contribute to high ability.

    Evidence suggests that children's self-perceptions of their abilities predict their school achievement even after one accounts for their tested cognitive ability (IQ). However, the roles of nature and nurture in the association between school achievement and self-perceived abilities (SPAs), independent of IQ, is unknown. Here we reveal that there are substantial genetic influences on SPAs and that there is genetic covariance between SPAs and achievement independent of IQ. Although it has been assumed that the origins of SPAs are environmental, this first genetic analysis of SPAs yielded a heritability of 51% in a sample of 3,785 pairs of twins, whereas shared environment accounted for only 2% of the variance in SPAs. Moreover, multivariate genetic analyses indicated that SPAs predict school achievement independently of IQ for genetic rather than environmental reasons. It should therefore be possible to identify "SPA genes" that predict school achievement independently of "IQ genes."

    The heritability of g is substantial. It increases from a low value in early childhood of about 30%, to well over 50% in adulthood, which continues into old age. Despite this, there is still almost no replicated evidence concerning the individual genes, which have variants that contribute to intelligence differences
    Strong genetic influences (on the order of 70–90% of variance) have been reported for many brain structures, components, and regions in adults, including gray and/or white matter volumes and/or densities in corpus callosum, superior frontal and temporal cortex, medial frontal cortex, amygdala, hippocampus, Broca’s area, anterior cingulate, Heschl’s gyrus, postcentral gyrus, and overall brain volume (Hulshoff Pol et al. 2006; Pennington et al. 2000; Peper et al. 2007; Posthuma et al. 2002; Thompson et al. 2001). Many of these genetic influences have also been linked to g and/or intelligence (Hulshoff Pol et al. 2006; Peper et al. 2007; Posthuma et al. 2002). Similar data have been reported for aspects of brain function that may be related to intelligence, such as the dynamic complexity of measuring brain oscillations assessing executive function output (Anokhin et al. 2006), suggesting that these physiological brain measures may be endophenotypes (Gottesman and Gould 2003), or physiological markers of intelligence. Similar data have also been reported for performance on tasks considered by many to reflect more elementary information processing capacity, than performance on intelligence tests (Roberts and Stankov 1999), such as inspection time (Edmonds et al. 2008) and executive control (Friedman et al. 2008). Moreover, even in 10-year-old, genetic correlations among different aspects of intelligence such as reading and mathematics abilities have shown substantial genetic correlations (Davis et al. 2008).

    . Although it is reasonable to suppose that genetic effects on specific learning abilities, such as reading and mathematics, as well as general cognitive ability (g), will overlap very little, the counterintuitive finding emerging from multivariate genetic studies is that the same genes affect these diverse learning abilities: a Generalist Genes hypothesis. To conclusively test this hypothesis, we exploited the widespread access to inexpensive and fast Internet connections in the UK to assess 2541 pairs of 10-year-old twins for reading, mathematics and g, using a web-based test battery. Heritabilities were 0.38 for reading, 0.49 for mathematics and 0.44 for g. Multivariate genetic analysis showed substantial genetic correlations between learning abilities: 0.57 between reading and mathematics, 0.61 between reading and g, and 0.75 between mathematics and g, providing strong support for the Generalist Genes hypothesis. If genetic effects on cognition are so general, the effects of these genes on the brain are also likely to be general.
  15. Jan 30, 2014 #14
    Then we get to the question of why don't they like it. Is that genetic?
    To address computer programming specifically, a person who doesn't find it interesting nearly to the point of addiction is severely handicapped. There is a huge amount on knowledge to absorb and many concepts that build on each other. What you should generally expect is that "happy engineering" (what use to be called "hacking", but now that term means malicious programming) should be easy, but when you tackle real projects, you have to push yourself.
    (edit: I just read Enigman's post. This is related to SPA's, that are believed to have a strong genetic component)

    The rules are semantic. And everyone I've tutored have roughly the same initial response to a new semantic rule - a rather plain reaction, as though they were rereading a news item to make sure they would remember it. When they start practicing with it, some seem to get it and others seem to be mechanical and hesitating. Some start to get happy about it. It's hard to be concise about what happens next, because different people learn math differently - but its' not just memory. My rote memory abilities are horrible, but my math skills are exceptional (as most among us are on this forum). Many of the students I've tutored can readily memorized a paragraph of text verbatim and are very slow at picking up math.
    Last edited: Jan 30, 2014
  16. Jan 30, 2014 #15
    It may very well be genetic. But to what extent, I'm not sure. What is in the child's upbringing would obviously be a factor. For example, if you surround a child with space ship toys, it wouldn't be surprising they'd become more interested in space. I don't think it's much of a big deal if SPA's are genetic, it's more of a big deal if success in a certain field is determined by your in built intelligence.

    Wait, when you say "a person who doesn't find it interesting nearly to the point of addiction is severely handicapped", it sounds like you are trying to say when someone finds something interesting to the point of addiction, they are severely handicapped, rather than the other way around. Since someone cannot become addicted to not liking something, that doesn't really make sense. Not to mention obsession is a handicap.

    Whenever I was learning new math concepts, I had a little trouble wrapping my head around them. But once I understood it, it became intuitive to me. I guess in this area your personal strengths can help you out. If you're not so good on memory, you can still excel in reasoning abilities, and vice versa. But if you're not at least decent in one or the other, you're pretty much screwed (as far as I know). I personally have no clue what my personal strengths are in this, I never studied high level maths in detail so I wouldn't really know. I'm probably going to have to learn it, since I'll be doing a computer science degree this year (which without a doubt will contain at least a decent amount of math).
  17. Jan 30, 2014 #16


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    Staff: Mentor

    Good place to close this.
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