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May 11, 2021 - Radio Renaissance - Jared Taylor
10:28
Heritability: Where Nature Meets Nurture
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Hello. My name is Jared Taylor.
I'm the editor of American Renaissance.
Today, I'd like to talk about heritability.
That is to say, about how genes influence human characteristics.
Scientists have long debated the question of how much we are influenced by our genes and how much by our environment.
But that debate is now approaching a consensus.
Virtually all scientists now agree that genes Play an important role in the development, not just of physical traits, but even human personality.
Most people have never doubted that physical traits, like hair and eye color or height, are largely inherited.
But to understand heritability, consider these two people.
One is 72 inches tall, the other is 67 inches tall.
Heritability doesn't explain how they grew to their respective heights, but how that five-inch difference came about.
By studying enough people, some related to each other, others not, researchers can determine what percentage of height variation is caused by genes and what percentage by the environment.
It turns out that the heritability of height is 80%.
Meaning that environment accounts for only 20% of the height difference.
Thus, genes accounted for 4 out of the 5 inch difference.
And environment accounted for just 1 inch.
Most people are surprised to learn how much genes affect psychological traits.
That's everything from intelligence to personality to mental illness.
But the scientific evidence for this, too, is now overwhelming.
Some of the most persuasive data in this area is from studies of identical twins who were separated at birth and given up for adoption to different families.
They make perfect research subjects because they're genetically identical, but they grew up in completely separate environments.
Often they didn't even know of the existence of the other twin.
By measuring just how similar these twins are, despite growing up in different families, Scientists can calculate how much of their various traits was contributed by genes and how much by environment.
That is the very question of heritability I was just talking about.
Thomas Bouchard of the University of Minnesota did the most famous research of this kind, the award-winning Minnesota Twin Study that tracked down and investigated hundreds of pairs of twins.
Imagine what it must have been like for grown-up people suddenly to meet an identical twin they had never even known about.
What startled both the twins and the scientists was just how incredibly similar the pairs of twins were.
They looked an awful lot alike, of course, but they were also very similar in their mannerisms and personalities.
Many had chosen the same profession, the same hobbies.
In one case, both twins had gone through very similar psychotic episodes during adolescence that had lasted for almost exactly the same amount of time.
The study really makes fascinating reading.
Professor Bouchard writes that his research showed that, quote, individual differences in most, if not all, reliably measured psychological traits, normal and abnormal, are substantively governed, substantively influenced,
When it comes to intelligence, Professor Bouchard concluded from his own and from other studies that the IQs of children can be strongly influenced by environment, but as people mature, their IQ scores increasingly reflect their genes.
He reports that the heritability of IQ among five-year-olds is only about 22%.
But for 26-year-olds, it's 88%.
This makes sense.
Children are malleable, and they can be influenced by environments that their parents choose for them.
By the time they're adults, though, they're less influenced by environment.
And in any case, they have chosen their own environments that suit their own inclinations.
That means parents and environment can have a temporary effect on children, but by the time we are adults, the differences in our intellectual abilities are almost entirely the result of genes.
happens.
Other scientists have calculated a heritability figure for IQ that may be a little bit lower than Professor Bouchard's 88%.
For example, David Kerp reported in a 2006 New York Times Magazine article that a survey of a century's worth of research This is not to say environment doesn't matter at all.
People who are severely malnourished, for example, they don't develop to their genetic potential.
But normal environments seem to have only a slight effect on adult IQ differences.
As a matter of fact, if parents want to give their children the best possible environment for IQ development, most of the time there's only one thing they can do that has a lasting effect, and that's breastfeeding.
If a mother keeps it up for at least six months, it usually raises IQ by five or even seven points.
For me as a father, it's pretty humbling.
To learn that probably nothing I've done for my children has any real long-term effect on their intelligence.
Even our personalities are largely affected by genes.
Psychologists talk about the Big Five, the best studied personality traits.
What we call, or what they call, extroversion, agreeableness, conscientiousness, neuroticism, and openness.
Again, Twin researchers found these traits are generally 40 to 60 percent heritable.
The table on your screen indicates more precise figures for them.
Believe it or not, even political attitudes are heritable.
Professor Bouchard cites a study of no fewer than 30,000 adults that concluded that political conservatism is 65 percent heritable in men and 45 percent in women.
Women, in other words, may be slightly more open to persuasion than men.
Professor Bouchard notes, however, that until about age 19, a young person's conservatism comes from his environment, from his family and surroundings.
But after that, after that age, his genes begin to influence his politics.
Alcoholism has a heritability of 50 to 60%.
Schizophrenia has a heritability of 80%, as much as height.
And by the way, adoption studies of all kinds confirm heritability.
By the time they're adults, adopted children resemble their adopted parents in only random ways, but they do resemble their biological parents, with whom they share 50% of their genes.
And this is true, not just for IQ and personality, but for such things as musical ability, And the likelihood of becoming a criminal.
The more closely related people are, the more similar they are.
But that's only circumstantial evidence for genes.
We have not yet found the actual genes that make people smart or extroverted or musical.
But we are getting close.
In 2011, a team led by Dr. Ian Deary of the University of Edinburgh Found the first incontrovertible evidence that certain combinations of DNA do mean higher or lower IQ.
A team of 32 researchers from around the world did massive calculations on the genotypes of more than 3,500 subjects and proved"biologically and unequivocally that purely genetic information can be used to predict intelligence." So far they've found only patterns of DNA that relate to intelligence,
not the actual genes.
But that day is not far off.
Within a few years, whether we like it or not, a scientist will be able to take a DNA sample from a newborn child and predict with remarkable accuracy how smart that child will be and even what that child's personality is likely to be.
We are not born We may think we establish our own personalities and choose the fields in which we are going to excel, but our genes set broad limits on what we can be.
Just as parents must realize the limits of their influence on their children, society must realize there are limits on what social programs can achieve.
No Child Left Behind is a good example of a government policy that completely ignores genetics.
It assumes that the school performance of all children can be raised to the average level or even higher.
By all means, let us do our best to help all children.
But the science of heredity tells us that some people will always be above average, some people will be below.
Much as we might want social programs to work miracles.
They just can't.
Policies must be based on scientific facts, not on fantasy.
I'll have more to say about this in a future video.
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