How much of personality and intelligence is genetically inherited?

[Oreka Bailoak]

I'm curious what people think.

How much of personality and intelligence do you think is genetically inherited?

(the non-genetic influence on intelligence and personality would be due to the environment; like education, nutrition, socio-economic status, peer influence, culture)

Dammit I messed up the poll, how do I allow multiple selections?

[Burgomaster]

I personally do not believe intelligence is genetically inherited (the same goes for personality).

Eg.

The average IQ of a British working class adult: 98

The average IQ of a British middle class adult: 108

In no way are the middle classes genetically superior to the lower classes. This just goes to show how important environmental influences have on intelligence.

[Neanderthal]

I think is more of an environment thing; My mother always had good notes at school, she has a Master degree and she is a teacher in one school and principal in another, but truth to be told I don't consider her to be particularly inteligent, she has this narrow minded/sheep like personality wich I dislike so much. And my father ha... well he is just a construction worker and a alcoholic. With this i'm not saying I cosidering myself far superior than them, my point is just that I think i'm more open minded and I have a bit more knowledge on certain matters than them both.

[The Ripper]

In no way are the middle classes genetically superior to the lower classes. This just goes to show how important environmental influences have on intelligence.

Why wouldn't the middle class be superior genetically, hypothetically speaking? What makes it such an impossibility?

I'm also interested in knowing where you got those stats.

[Curtis24]

I personally do not believe intelligence is genetically inherited (the same goes for personality).

Eg.

The average IQ of a British working class adult: 98

The average IQ of a British middle class adult: 108

In no way are the middle classes genetically superior to the lower classes. This just goes to show how important environmental influences have on intelligence.

Well, they probably are genetically superior, actually. That being said, malnutrition does have an effect... however, we're talking about African-like levels of malnutrition. Those conditions don't exist in the British working-class.

[Oreka Bailoak]

I figure I'll post my response after reading the 500 page book G-Factor by Arthur Jensen. Intelligence is WITHOUT A DOUBT AT LEAST over 50% genetically inherited. The evidence is overwhelming. Hundreds of studies and tens of thousands of people tested. I studied statistics in college and I'm familiar with the factor analysis used, as well as very familiar with the statistical terms used in the book (such as extrinsic correlation vs. intrinsic correlation). His work is very thorough and highly technical and he covers pretty much every topic to leave you beyond a reasonable doubt about his conclusion for the inheritance of intelligence.

There's huge amounts of evidence for a neurological basis for the difference in intelligence. Here's some notes I took from the book.

The physical correlates with g that are best understood are; stature (.1 to .3), head size and brain size (.1 to .25), myopia (.20 to .25), frequency of alpha brain waves, latency and amplitude of evoked brain potentials, rate of brain glucose metabolism and general health. It is clear that g is some product of human evolution. Of the above body size has been shown to be an extrinsic variable because of within family studies- in other words it’s simply due to the fact that more intelligent people marry taller partners rather than taller people being actually more. The rest are hypothesized as intrinsic correlates of g- in other words they probably physically influence g (for example siblings with myopia are smarter on average than their siblings without myopia). Electro chemical activity of the brain shows amazing correlations. For example, when subjects were placed in a room and told to relax those with higher levels of g showed more complex brain wave patterns and a higher natural brain alpha frequency. When a clicking is heard subjects with higher amounts of g shoed shorter latencies (faster neural action) more peaks and troughs (more zero crossings within a specified epoch), greater complexity (longer “string” measure) of AEP waves, lesser intraindividual variability (greater consistency), smaller amplitude in response to expected stimuli (more efficient expenditure of neural energy) as shown by the positron emission tomography scan studies. Correlations with these AEP variables and IQ typically range between .3 and .6. When subjects were injected with radioactive glucose and then took an IQ test (Raven Advanced Progressive Matrices), while being PET scanned, cerebral glucose metabolism found that higher scoring subjects use less brain energy than lower scoring subjects during the IQ test. So g is related to efficiency of neural activity involved in information processing and problem solving. Left handed people have been found to test more often at extremes of the IQ test than right handed people. General health or physical wellbeing has been found to correlate with IQ at .381 (while there’s only a .076 correlation between health and socioeconomic status) The heritability of IQ is estimated at .4-.5 in children, .6-.7 in young adults, and .8 by later in life.

The word intelligence is not universally defined by academia so the term g was created to describe certain mental performance on various tasks. G stands for general intelligence factor- it is some physical neural aspect of the mind that influences performance on numerous mental tasks. The certain mental tasks that correlate with a high amount of g are (between .94 and .73); matrix relations, generalizations, series completion, verbal analysis, likeness relation, problem arithmetic, paragraph comprehension, perceptual analogies. Mental tasks that have low (between .31 and .04) (but still positive) correlations with g are maze speed, cross out 4’s, counting dots, simple addition, tapping speed, dotting speed, paired associates memory, recognition memory. The WAIS IQ test (Wechsler Intelligence scale for adults) has a .95 correlation with g. Another interesting heritable law concerning IQ (and therefore also g) is that in a mixed racial- black, white and Asian- gifted class where a requirement of a 120 IQ test is required for admittance, 33% of white students had a sibling that scored above 120 but only 12% of black students had a sibling that scored above 120. This strange statistic is explained by the statistical concept of regression to the mean. G is also often a highly valuable predictor of job performance. The US Air Force used 14 tests to predict job performance for fighter pilots and navigation pilots and found a correlation with g of .398 and .482 respectively (the non g factors were .02 and .084).
(! It's so amazying that they've actually found the parts of the brain that make people smarter- but today I feel like nobody even knows these facts!) It's probably political correctness keeping the facts about genetic inheritance of intelligence out of our schools.

The studies on heritability are based off studying the IQ of parents of an adopted child and that adopted child raised in a high SES family. Interracial adoptions, and by studying siblings parents, grandparents, cousins, twins, testing throughout life etc. (the IQ test is not something that people with the most basic education can study to improve their score- it uses the limits of your mental ability, many people can't improve their score above 5 points and almost nobody improves over 10 points.) And they found that The heritability of IQ is estimated at .4-.5 in children, .6-.7 in young adults, and .8 by later in life.
-------------------------------------------------------------
Now for personality.


Domain Heritability
Openness to Experience 57%
Extraversion 54%
Conscientiousness 49%
Neuroticism 48%
Agreeableness 42%

^The studies on personality are also very detailed.
http://en.wikipedia.org/wiki/Big_Five_personality_traits

Anyways the statistical theory behind the discovery of G and the 5 major personality factors is this...

(footnote: If you’re interested in how g was statistically derived- factor analysis is the statistical method used to prove the existence of g. Factor analysis is not bound to produce a general factor. A general factor emerges from a hierarchical factor analysis if and only if a general factor is latent in the particular correlation matrix. A general factor derived from hierarchical analysis should be based on a matrix of positive correlations that has at least 3 latent roots (eigen values) greater than one. For proof that a g factor is not inevitable look at personality studies. The myriad of inventories that measure various personality traits have been subjected to every type of factor analysis, yet no general factor has ever emerged in the personality domain. There are however, a great many first-order group factors and several clearly identified second order group factors, or “super factors” (extroversion, introversion, neuroticism, and psychoticism) but no general factor. Similarly, the correlations among various measures of athletic ability show a substantial general factor.)

So I say above .5 for personality and above .5 for intelligence.

[Oreka Bailoak]

Originally Posted by Hellhammer:
she has this narrow minded/sheep like personality
Yes, I know exactly what you're talking about.

Intelligence is defined differently by different people. Some people like me associate intelligence with the concept g- which is a neurological ability (caused by having a more capable and efficient brain) and it reflects itself in being capable to preform higher in mental abilities than average people.

Personality to me is entirely separate from intelligence. It's possible to have people that are incredibly intelligent but heading into the entirely wrong direction in life and have absolutely bad personality traits.

[Frederick]

Question is, why does the average IQ drop?
Is our DNA out of order? Or do only stupid people have kids?

From the 1920 til 1990, average IQ of 18 year olds increased by 40 points. (on a test from the 1920s).

1990 the trend turned. (coincidence or not, 1990 was also a turn of the trend in agression and violence in teenagers)

Between 1990 and 2000, the average IQ of 18 year olds dropped by 1 Point per year. (means, a person, who reached 18 years of age in 1990 performs 10 points better than a person who reached 18 in the year 2000)

US-Phsychologists named it the "MTV-Effect" in 1997 and claimed Music TV is responsable for the stupidification of the youth.

From the year 2000 til the year 2010 the average IQ of 18 year olds dropped by 2 points per year. (means, on an IQ Test of the 1920s, a person who reached 18 by the year 2010 performes 30 points lower than a person who reached 18 in 1990 wich means, we lost almost all the IQ gain between 1920 and 1990. (also, the year 2000 marks another accerlation in the agression/violence/rebellion levels of the youth)

Wich of course sounds quiet rediculous, since 30 points above average are called "gifted" (top 2%), what would mean, a "gifted" 18 year old of 2010 is only equal to an "normal intelligent" 18 year old of 1990.

Meanwhile some come up with terms like "Digital Dementia". Stupidification by letting computers, iphones etc do what older generations had to do with their brains.

But maybe its truth.
Companies in Germany often claim, modern young people are so ridicilousy stupid, they are of no use. Even if they come with university entrance diplomas.

And if I now imagine that Germany is the leading white country, if it comes to average IQ.... I dont want to know whats up with the rest of the white world. ;)

So whats up?
Digital dementia or do only stupid people have kids, these days?

[Oreka Bailoak]

So whats up?
Digital dementia or do only stupid people have kids, these days?

That's really a great question.

Charles A. Murray from AEI is coming out with a new book about this very topic.

You can watch his video about it here...
http://www.aei.org/video/101414

Basically what has happened is Flynn effect coupled with a Dysgenic trend. Let me explain.

The Flynn effect is when IQ raises by increasing nutrition, increasing education, breast feeding (which has been proved to increase IQ by about 7 points- and damnit I'm allergic to milk)

What you are seeing today is that the Flynn effect has already ran its course. There is currently no longer in a country like America any more room to increase IQ by better nutrition, education and etc.

All the while this was happening there has been evidence of a Dysgenic trend and since the Flynn effect has reached its asymptote the Dysgeneic trend is what is seen. (Dysgenic means that we are increasing more of an unfavorable trait- in this case the unfavorable trait is low IQ (and probably also bad personalities))

It's crystal clear why this is happening... look at this chart.


Blacks IQ : Birth Rate : % population
<71 : 2.6 : 16
71-85: 2.12 :34
86-100 : 1.79 : 34
101-115 : 1.63 : 13
116-130 : 1.2 : 4
130+ : 0 : .01


Whites IQ : Birth Rate : %population
<71 : 1.59 : 2
71-85 : 1.68 : 13
86-100 : 1.74 :34
101-115 : 1.44 :34
116-130 : 1.15 :13
130+ : .92 : 2
(keep in mind IQ is mainly genetically inherited)

The current generation is going to decrease IQ by about 2 points from this generation into next generation. (for whites it's actually just under a 2 point drop and for blacks it's just over a 2 point drop). And after that the trend should continue for the next generation and the next etc.

[Frederick]

The Flynn effect is when IQ raises by increasing nutrition, increasing education, breast feeding (which has been proved to increase IQ by about 7 points- and damnit I'm allergic to milk)
Hmm. Interesting.
I was breastfeeded + I became 18 in 1990, when Germanies IQ was at its top.
And I am born in a region of Germany wich is "above German average" in IQ. However not in a "Far above German average" region. Such regions only exist in southern Germany.

My IQ is at 135 (best trait is Spatial/visual thinking, wich is at 160).
It was measured in my teenager time in a psychatric clinic, in wich I spend some time for therapy because of "selfdestructive tendencies". :eusa_shifty:

[Oreka Bailoak]

My IQ is at 135 (best trait is Spatial/visual thinking, wich is at 160).

Dadgum, I have a chart that links IQ to jobs and you should either be a CEO of a company, a doctor, a scientist, or a college professor.


Such regions only exist in southern Germany.
Haha, my German ancestors are directly from the middle of that high IQ region.

[Quasimodem]

No one can give an absolute answer to this poll, since heritability depends on how environments differ in the population you're looking at, of course.

[_______]

I personally do not believe intelligence is genetically inherited (the same goes for personality).

Eg.

The average IQ of a British working class adult: 98

The average IQ of a British middle class adult: 108

In no way are the middle classes genetically superior to the lower classes. This just goes to show how important environmental influences have on intelligence.

wrong :P

[Oreka Bailoak]

No one can give an absolute answer to this poll, since heritability depends on how environments differ in the population you're looking at, of course.
What an overgeneralized comment. Nobody is saying- nor have they ever said something like- "Genetics accounts for EXACTLY 67.389% for EVERY individual on the planet for intelligence and 32.611% of the difference in intelligence is due to the environment- and no other percentage is acceptable".

Through the hundreds of statistical studies, analyzed every which way, there's profound information that can be deduced- Both personality and g are influenced greatly by genetics- this was my point in making this thread.

Evidence shows that it's AT LEAST over 50% due to genetics for intelligence (g) in every human population! (though I think it's closer to 70%) and about 50% for personality.

Often those who say that we don't know enough to come to any conclusions- or that strange exceptions exist that force us to throw away all the hundreds of logical experiments- have never in their life, once read a book detailing the numerous statistical studies which all come to similar conclusions. This is not a coincidence.

You can read any accredited Scientific Journal today because the scientific community overwhelmingly accepts these conclusions because the data is extremely sound and thorough.

[Quasimodem]

What an overgeneralized comment. Nobody is saying- nor have they ever said something like- "Genetics accounts for EXACTLY 67.389% for EVERY individual on the planet for intelligence and 32.611% of the difference in intelligence is due to the environment- and no other percentage is acceptable".

Through the hundreds of statistical studies, analyzed every which way, there's profound information that can be deduced- Both personality and g are influenced greatly by genetics- this was my point in making this thread.

This is probably true.


Evidence shows that it's AT LEAST over 50% due to genetics for intelligence (g) in every human population! (though I think it's closer to 70%) and about 50% for personality.

Often those who say that we don't know enough to come to any conclusions- or that strange exceptions exist that force us to throw away all the hundreds of logical experiments- have never in their life, once read a book detailing the numerous statistical studies which all come to similar conclusions. This is not a coincidence.

You can read any accredited Scientific Journal today because the scientific community overwhelmingly accepts these conclusions because the data is extremely sound and thorough.

Heritability doesn't mean the percentage that's caused by genetics. No, heritability is the percentage of variation in a population that's due to differences in genetics, as opposed to differences in environment. For example, height is partially acquired by genetic factors and partially acquired by environmental factors. If you have a very unequal society, where the rich have access to all the goods they like and the poor are malnourished the heritability will be low because your height will be determined largely due to whether you're born into the rich class or the poor class. On the other hand, if everyone has quite similar opportunities/environment, the heritability in that population will be higher, even though their genetics may as well be the same.

[Phil75231]

I voted genetics between 25 and 75 percent, but I think it's very much closer to 25%.

Furthermore, intellgence is a very nuanced concept. There's IQ type intelligence (biased in favor of formal education), then there's artistic intelligence (Picasso, Dali, etc), then there's social intelligence, and so on and so forth. That means we have to identify a specific type of intelligence before this poll has even a fighting chance to be meaningful (I personally had in mind "intelligence" of any and/or all sorts).

AFAIK, the only way intelligence can be close to 100% heritable is when considering entirely different species. However, I assumed the OP meant intelligence ONLY among humans, and so voted the way I did on that basis.

[Damião de Góis]

I don't know how much it is inherited but intelligence is much more a product of education and growing up environment than genetics.

[Oreka Bailoak]

Heritability doesn't mean the percentage that's caused by genetics. No, heritability is the percentage of variation in a population that's due to differences in genetics, as opposed to differences in environment. For example, height is partially acquired by genetic factors and partially acquired by environmental factors. If you have a very unequal society, where the rich have access to all the goods they like and the poor are malnourished the heritability will be low because your height will be determined largely due to whether you're born into the rich class or the poor class. On the other hand, if everyone has quite similar opportunities/environment, the heritability in that population will be higher, even though their genetics may as well be the same.

The statistical analysis has taken this into account already. It doesn't change the conclusion.


I don't know how much it is inherited but intelligence is much more a product of education and growing up environment than genetics.

Actually thousands of cases of twins raised apart, adoption studies of twins, testing siblings, siblings raised apart, cousins, parents and their children and countless other studies show that intelligence in the long run is mostly due to genetics (over 50%).

[safinator]

Dadgum, I have a chart that links IQ to jobs and you should either be a CEO of a company, a doctor, a scientist, or a college professor.

When it comes to success in life Hard Working is far more Important than IQ i've noted this in every place.

[Quasimodem]

The statistical analysis has taken this into account already. It doesn't change the conclusion.

What do you mean "it's been taken into account"? I said that heritability differs depending on how equal the environmental factors are, so you can't put a percentage on it that applies to all cases.

[Oreka Bailoak]

When it comes to success in life Hard Working is far more Important than IQ i've noted this in every place.


It depends upon what defines success. If success means becoming a PhD physicist then IQ is incredibly important- if it means becoming a ground breaking PhD physicist then high IQ along with a hard working personality is vital. In that book 'G-Factor' I took some notes about Uric acid influence on personality....

"Uric acid acts as brain stimulant, and studies show that people with higher uric acid levels will have more achievements than others even with similar IQ (even after adjusting for a similar social, cultural, background, and lifestyle). Uric acid is only slightly correlated with IQ but very correlated to achievement and ambition."

"Another interesting personality factor is typical intellectual engagement (TIE)- which shows how often an individual does g related tasks- TIE correlates with the two of the ‘Big 5 Personality Factors’- both ‘openness’ and ‘conscientiousness’ at +.60. Abilities, interests and personality develop in tandem such that ability level and personality disposition determine probability of success in a particular task domain and interests determine the motivation for attempting the task. "