Smart people often underestimate their intelligence

"Smart parents are more likely to have children who are a little less smart"

Character and talent are already predetermined at birth, says behavioral scientist Robert Plomin. Hard to believe? A conversation about unsuccessful upbringing and the opportunities of modern genetic research

Interview: Vivian Pasquet

GEO: I've always had no handicraft skills, but I did quite well at school. I am empathetic and helpful, but not particularly brave and far too quick-tempered. If I believe your research, my parents' upbringing didn't add anything to any of this. Instead, my genes are primarily to blame. How did you come to this assertion?

Robert Plomin: The influence of genes has been massively underestimated for decades. As early as the 1970s and 1980s, we were able to show that adoptive children do not resemble their adoptive parents. Instead, they resemble their birth parents - not only outwardly, but also in terms of intelligence and character traits, although they have never met them in life. There are also a number of studies with identical twins, genetic clones. There are cases in which these twins grew up in separate families, but still have the same character traits. Whether we are brave or not, musical or funny, empathetic, introverted: we know today that at least 50 percent of every quality is in our genes at birth.

But I also see myself as a result of the upbringing and care of my parents.

I have to disappoint you there. Your parents may have given you opportunities as a child. Your genes, however, determine whether you have seized these opportunities and who you are today. At its core, parenting does not make you who you are.

But it also depends on my environment, who I meet in life and what opportunities I get.

Stop, now mix something up. In principle, the environment is everything that cannot be explained by genes. Strokes of fate, encounters or opportunities that you get in life. The most important thing about these factors is that chance alone decides whether they will take place and what consequences this will have for your life. Parents are of course also the environment, but the word "upbringing" means that this part of the environment can be controlled in a targeted manner. Parents' guidebooks lead parents to believe that if you behave like this, it has these and that consequences for the child. Many parents believe that. Until they have the second child and find out: Despite the same upbringing, the result is a completely different person.

But the fact that I'm not a hooligan, even though I have a quick temper, has something to do with my upbringing, doesn't it?

Of course, you have been taught behaviors. But that didn't change your core - because you're a genetic hothead. You have been since you were born. Your parents did not teach you any character traits.

Why is this realization so important?

Because believing they are responsible for their child's character or even mental illness can destroy parents. It used to be thought that schizophrenia was caused by the mother neglecting her child. Why, given the same upbringing, one sibling became schizophrenic and the other did not, no one asked. Terrible what that meant for the affected mothers. Today we know that schizophrenia is hereditary. Thousands upon thousands of mothers have been totally unjustly accused.

Or many people today believe that parents are responsible if their child is too fat. The body mass index is about 70 percent hereditary. You can see that in adopted children. Although they grow up in the same environment as their adoptive siblings, they usually approach the weight of their birth parents; not just because of their metabolism, but also because of their behavior: they eat more.

What about common character traits? Curiosity, ambition, wit?

Think of children who are very fond of reading. One often hears: the parents read a lot, live it to the child, and that's why it reads too. The fact that there are also children who do not read even though the house is full of books is simply ignored in this claim. This lacks any evidence that is required everywhere else in science.
I myself come from a poorly educated family. We didn't have any books, nobody went to college. Even so, I went to the library, studied hard, and later made it to university. My sister is completely different. She had a hard time studying and my parents had to help her with her homework.

In doing so, you are denying your parents that you have contributed to your success. What did your mother say about that?

My parents were proud of me, of course. They had all of my books on the shelf. But honestly, I don't think you read it. And I have to correct you. My parents did a lot for me: by passing their genes on to me.

For statistical reasons, the intelligence of children approaches the average values ​​in a population over generations. This means that parents who are above-average smart are more likely to have children who are a little less smart than they are, and vice versa. And sometimes the pendulum even swings in the opposite direction. You can see this in child prodigies: They often have only average intelligent parents. This is an important message: there are no genetic castes.

You argue a lot with behavioral studies, but so far the right gene has not been found for intelligence, courage or empathy.

Who says that there can only be a single gene that is responsible for a property? Scientists have long been looking at entire gene complexes to find out what makes us who we are. Millions of people have had their DNA decoded since the early noughties. Scientists are now evaluating their data. For example, they check in which parts the DNA of particularly smart, anxious, alcohol-dependent or depressed people is similar. A number of patterns have already been discovered that are shared by people with certain skills.

Does this work for every property?

It will eventually be possible for every property imaginable. The more people have their genome sequenced and the cheaper such tests become, the more information we will have. We already know a lot from behavioral studies with twins and adopted children, but now we have finally found a statistical means that can also be used to prove this in molecular biology.

In your book “Blueprint - How DNA makes us who we are”, you write that only about eleven percent of school success can be explained with the help of this new technology. That is far from 50 percent genetic influence.

Don't be so impatient! So far, researchers have only found a fraction of gene combinations that are responsible for character traits. But the successes are progressing at an impressive pace.

So you could examine the DNA of infants as soon as they are born and see what to expect?

Exactly. In some cases, we've been doing this for years - for example, by scanning for the most common genetic diseases shortly after birth in order to treat them at an early stage.

About Robert Plomin

The psychologist Robert Plomin, 71, is researching at King's College in London how genes shape our behavior. He became known worldwide through twin studies. In his book "Blueprint - How DNA makes us who we are" (Allen Lane, so far only in English) he takes stock of more than 40 years of research. His theses on the role of upbringing or the inheritance of intelligence are controversial in specialist circles.

That makes sense in the case of serious illnesses. But pre-determining mental illnesses or traits can also be dangerous.

Everywhere in medicine people talk about the importance of prevention. Today, however, depression is only treated when symptoms appear. Or you can only support a child with poor reading spelling when they are already having problems at school. With the help of modern genetic engineering, you will be able to do this in a much more targeted, individual and above all in good time in the future.

But you said earlier that you can't specifically influence the environment?

At least not for the masses. You can hardly provide every child with a private coach for all conceivable weaknesses and strengths - regardless of whether they have them or not.
However, if you already know at birth that a child could have problems with reading, then you can give them specific reading support. The genes are not your destiny, which you can not do anything about.

However, these tests are still quite imprecise. Instead, it could end in a self-fulfilling prophecy: the child thinks they have an innate reading disorder and then actually develops one.

This is your hypothesis. There are other hypotheses that are much closer to the truth. Let's take the subject of obesity. I've had my genes checked and I know I have a tendency to be fat. But I didn't give up because I'm a genetic fat paunch. On the contrary: Since I have known that I tend to be fat, I feel motivated to pay even more attention to my diet.

What about mental health problems that are much more obscure? If I knew that I am prone to depression, I would often think during sad moments: "Now the disease is breaking out."

I do not believe that. Knowing your predisposition to psychological weaknesses and strengths can be very beneficial. Also because they become more and more pronounced in the course of life.

What does that mean?

The reasons for this are not known, but over the years you become more and more of the person you genetically are. This also explains why we become more and more similar to our parents in old age. Not only externally, but also in character.

Oh my God.

Don't be so negative! For many people it is very liberating to know what makes them who they are.

Since “Blueprint” came out, you have to deal with serious allegations. The message of your book, say critics, is strongly reminiscent of racist inheritance teachings, for example from the “Third Reich”.

Oh come on! Those are the classic accusations made by journalists or academics, where criticism is part of the good form. A bad person doesn't need my knowledge to build a totalitarian system. Just think of North Korea: They believe in the influences of the environment, namely that they can educate their citizens in the interests of the state. Nobody there justifies the oppression of the people with genetic teachings.

But what if less intelligent children get poorer chances in life due to genetic tests or are already aborted in the womb?

You seem genuinely prone to pessimism. The idea that my research could be misused in this way did not have an impartial reader. But for them I wrote the book: Parents or people who wonder what makes them who they are. These readers are tirelessly thanking me for understanding their children or themselves better after reading the book.

Also think of all the people who went to psychotherapy for years and looked for the causes of their depression in the past. I know people who haven't spoken to their parents for years because they believed that their upbringing was to blame for their condition. Fortunately, the zeitgeist is changing. Even psychotherapists today know what is far more important than digging in the past: looking ahead and dealing with what is.

Patients who have experienced severe trauma will not see it that way.

You argue with extremes. If you lock your child in a closet and not talk to them, it will of course have an impact on their life. I am talking about averages, however. From a certain population at a certain point in time. And most of them are not mistreated.

Are you really not afraid of the consequences of genetic research?

No I did not. I am looking forward to witnessing this at the end of my professional career. I believe that we can also see some people's weaknesses with more respect, because we know that they may not be responsible for it. Genetic research makes the world better, not worse.

If your theories are correct, can a murderer still be severely punished? After all, he can't help his character.

But of course he can do something about it. After all, he is still in control of his actions. If you are alcohol addicted, driving while drunk is still a criminal offense. Nowadays, courts do not readily accept it as an excuse if someone argues with the environment instead of genes - that is, wants to assert their bad childhood. Instead, I believe that we can even use genetic research to prevent crime. Not by weeding out these people, but by offering them help in good time.

That sounds too good to be true.

I am an optimist. I guess it's in my genes.