Genetic research "Smart parents are more likely to have kids who are a little less smart"
Interview: Vivian Pasquet
GEO: I’ve always been untalented with my hands, but quite good at school. I am empathic and helpful, but not very brave and much too hot-tempered. If I believe your research, my parents’ upbringing contributed nothing to all this. Instead, my genes are mainly to blame. How do you come to this assertion?
Robert Plomin: The influence of genes has been massively underestimated for decades. Thereby we could already show in the 1970s and 1980s that adopted children do not resemble their adoptive parents. Instead, they resemble their biological parents – not only in appearance, but also in intelligence and character traits, although they never met them in life. In addition there are several studies with identical twins, genetic clones. There are cases where 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 now know that at least 50 percent of every trait is in our genes at birth.
But I also perceive myself as a result of my parents’ education and care.
I am sorry to disappoint you. Your parents may have given you options as a child. Whether you took advantage of these opportunities and who you are today is determined above all by your genes. Education does not, at its core, make you the person you are.
Role understanding job, family, double burden: where is the way out for mothers?
But it also depends on my environment, on who I meet in life and what opportunities I get.
Stop, now you are mixing things up. In principle, environment is everything that cannot be explained by genes. Strokes of fate, encounters or opportunities you get in life. The most important thing about these factors is that chance alone decides whether they take place and what the consequences are for your life. Parents are of course also environment, but the word "education" means that you can specifically control this part of the environment. Parenting guides fool parents: If you behave this way and that way, it will have this and that consequence for the child. Many parents believe that. Until they have the second child and realize: Despite the same upbringing, a completely different person comes out.
But the fact that I am not a hooligan, even though I have a quick-tempered character, has something to do with my upbringing, doesn’t it??
Of course you were taught behaviors. But that did not change your core – because you are a genetic hothead. You have been since birth. Your parents did not teach you any character traits.
Why is this insight so important?
Because it can destroy parents if they believe they are responsible for their child’s character or even mental illnesses. In the past, schizophrenia was thought to be caused by a mother neglecting her child. No one asked why one sibling became schizophrenic and the other did not, given the same upbringing. It was horrible what this meant for the mothers affected. Today we know that schizophrenia is hereditary. Thousands and thousands of mothers have been accused completely wrongly.
Or today many people believe that parents are responsible if their child is too fat. Yet 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 only because of their metabolism, but also because of their behavior: they eat more.
What about common traits? Inquisitiveness, ambition, wit?
Think of children who like to read very much. One often hears: The parents read a lot, live it out to the child, and that’s why the child reads. 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. That lacks any evidence, which is demanded everywhere else in science.
I myself come from an educationally weak family. We didn’t have books, nobody went to university. Nevertheless, I ran to the library, studied hard and later made it to university. My sister is completely different. She struggled with learning, my parents had to help her with her homework.
You deny with it your parents to have contributed something to your success. What did your mother say?
My parents were proud of me, of course. They had all my books on the shelf. But honestly, I don’t think they read them. And I must correct you. My parents did a lot for me: by passing on their genes to me.
For statistical reasons, children’s intelligence approaches the average values in a population over generations. That is, parents who are smarter than average are more likely to have children who are slightly less smart than they are, and vice versa. And sometimes the pendulum even swings in the opposite direction. You can observe this in prodigies: They often have only averagely intelligent parents. This is an important message: there are no genetic castes.
They argue a lot with behavioral studies, but so far no gene has been found for intelligence, courage or empathy.
Who says it can only be a single gene that is responsible for a trait? Scientists have long been looking at entire gene complexes to find out what makes us who we are. Since the early noughties, millions of people have had their DNA decoded. Scientists are now evaluating their data. For example, they check in which parts the DNA of particularly smart, anxious, alcoholic or depressive people resembles each other. Several patterns have already been discovered, which are shared by people with certain abilities.
Does that work for every trait?
It will eventually be possible for every trait imaginable. The more people have their genome sequenced and the cheaper such studies 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 to prove it molecularly as well.
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! Researchers have found only a fraction of gene combinations that are responsible for character traits. But the successes are progressing at an impressive pace.
So you could study the DNA of babies right after they are born and see what’s in store for them?
Exactly. In some cases, this has been done 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
Psychologist Robert Plomin, 71, conducts research at King’s College in London on 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 about the role of upbringing or heredity of intelligence are controversial among experts.
This makes sense in the case of severe diseases. But predetermining mental illnesses or characteristics can also be dangerous.
Everywhere in medicine, people talk about the importance of prevention. Today, however, depression is not treated until symptoms appear. Or a child with a dyslexia is not supported until he or she is already having problems at school. With the help of modern genetic engineering, you will be able to do this in the future in a much more targeted, individualized and, above all, timely manner.
But you said earlier that you cannot influence the environment in a targeted way?
At least not for the masses. You cannot preventively provide every child with a private coach for all conceivable weaknesses and strengths – regardless of whether they have them or not.
But if you know at birth that a child might have problems with reading, then you can specifically help him or her with reading. The genes are not your fate, against which you can do nothing.
But these tests are still quite inaccurate. It could instead end in a self-fulfilling prophecy: The child thinks he has a congenital reading disability, and then really develops one.
This is your hypothesis. There are other hypotheses that are much closer to the truth. Let’s take the topic of obesity. I have had my genes tested and know that I tend to be fat. But I didn’t give up because I’m a genetic fatty. On the contrary, since I know that I tend to be fat, I feel motivated to pay even more attention to my diet.
What about psychological problems, which are much more elusive? If I knew that I was prone to depression, I would often think during sad moments: "Now the disease breaks out."
I do not think so. It can be very healing to know about his predisposition to psychological weaknesses and strengths. Also because, after all, they become more and more pronounced in the course of life.
What does that mean?
While you don’t know the reasons for this, as the years go by you become more and more the person you genetically are. This also explains why we look more and more like our parents as we grow older. 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 the person they are.
Since the publication of "Blueprint," you have nevertheless had to deal with fierce accusations. The message of your book, critics say, is strongly reminiscent of racist heredity teachings, such as from the "Third Reich".
Oh, come on! These are the classic accusations of journalists or academics, for whom criticism is part of good manners. A bad person doesn’t need my insights to build a totalitarian system. Think about North Korea: there they believe in the influence of the environment, namely that you can educate the citizens in the sense of the state. No one there justifies the oppression of the people with genetic teachings.
But what if less intelligent children get worse chances in life because of genetic tests or are already aborted in the womb??
You seem to be really inclined to pessimism. The idea that my research could be abused in this way was not one that an unbiased reader would have had. But it is for them that I have written this book: Parents or people who wonder what makes them the person they are. These readers thank me by the dozen for helping them understand their children or themselves better after reading the book.
Think of all the people who have gone to psychotherapy for years and have looked for causes for their depression in their past. I know people who didn’t talk to their parents for years because they believed their upbringing was to blame for their condition. Fortunately, the zeitgeist changes. Even psychotherapists today know what is much more important than digging into the past: looking forward and dealing with what is.
But patients who have experienced severe trauma will not see it that way.
They argue with extremes. If you lock your child in a closet and don’t talk to him, of course it will have an impact on his life. But I am talking about averages. From a certain population at a certain time. And most of them will not be mistreated.
Are you really not afraid of the consequences of genetic research?
No, I have not. I am glad to be able to witness 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 able to help it. The world is getting better from genetic research, not worse.
If your theories are correct, one may still punish a murderer hard? After all, he can’t help his character.
But of course it’s his fault. After all, he is still the master of his deeds. If you are prone to alcoholism, it is still a crime to drive drunk. Today, courts do not easily accept as an excuse someone who argues with environment instead of genes – i.e. wants to claim his bad childhood. Instead, I believe that we can even prevent crimes with the help of genetic research. Not by weeding these people out, but by offering them help in a timely manner.