Question 1

Does parenting make a difference?

Robert Plomin · Accepted Answer

In Blueprint, I have a section called ‘Parents matter, but they don’t make a difference’ (pp. 82-86). Parents obviously matter tremendously in their children’s lives. But differences in parenting – the affection, discipline, control they provide – do not make a difference in how their children turn out in the long run.  Environmental differences explain the other half of the differences between children not explained by genetics, but these environmental influences are not the systematic effect of differences in parenting. (I am currently writing a follow-up to Blueprint which will focus on genetics and parenting – it’s working title is Parenting after the DNA Revolution.)

Question 2

I always score high in Neuroticism on personality tests. I know that I probably inherited this. I keep reading about how bad it is for mental and physical health. Is there anything that I can do to change it?

Robert Plomin · Accepted Answer

One of my mantras is that heritability does not imply immutability. Heritability means that on average in the populations studied in genetic research, inherited DNA differences account for differences in neuroticism. That is, genetic research describes ‘what is’ – it doesn’t limit ‘what can be’. (This is described at length in my book, Blueprint: How DNA Makes Us Who We Are.)

Question 3

Is nicotine addiction hereditary?

Robert Plomin · Accepted Answer

You can’t find a single psychological trait that can be measured reliably that does NOT show genetic influence. So, no surprise, individual differences in smoking and nicotine show moderate genetic influence. There are several interesting issues here, which are discussed on pages 284-288 of the 7th edition of our textbook, Behavioral Genetics.

Question 4

Could modern genetic testing lend itself to a resurgence of eugenics, such as the prohibition of racial mixing?

Robert Plomin · Accepted Answer

I think the more we know about ancestry, the more we realise what a hodge-podge of ancestral DNA we all are. At the end of the paperback edition of my book Blueprint, in a section called ‘Afterword’ (pp. 193-194), I talk about this issue of eugenics as a question I am frequently asked. Here’s one aspect of the conversation that I find interesting. Totalitarian regimes like Nazi Germany do evil things, but they don’t need a rationale to do it.  The Nazis misappropriated genetics as a rationale to justify their atrocities. However, most totalitarian regimes assume an environmental rationale: that people can be moulded as the state wishes. For example, Stalin’s USSR, the 1948 model for George Orwell’s 1984, actively denied genetics and purged scientists who believed in it.  During Stalin’s Great Purge, millions of citizens deemed ‘enemies of the working class’ were imprisoned or killed. Other examples of totalitarian regimes with an environmental rationale include Mao’s China and the Kim dynasty in North Korea.

Question 5

I am in the process of choosing a sperm donor. Can I predict the IQ, height, eye color, and personality of my unborn child by choosing a specific type of donor?

Robert Plomin · Accepted Answer

Height and eye color are very highly heritable, IQ is moderately heritable, and personality is modestly heritable. So, yes, your choice of a donor will affect these traits in your child.

Question 6

Research shows that obesity is one of the strongest genetically influenced traits we have. Could genetic testing lend itself to the marginalization of individuals more likely to suffer obesity?

Robert Plomin · Accepted Answer

I wish more people recognized the strong genetic contribution to weight to step back from the blaming and shaming that we see today. I don’t see why DNA testing would lead to the marginalization of individuals with obesity. My polygenic score for body mass index is my highest DNA risk score – my polygenic score is at the 94th percentile. It has been helpful for me to know that.  (This is described at length in my book, Blueprint: How DNA Makes Us Who We Are.)

Question 7

Parental and teacher perceptions and expectations of a student can be preconceived. Is it likely that knowledge from genetic testing could have an impact on a child's academic achievements and behavior?

Robert Plomin · Accepted Answer

My view is that the power of labelling is greatly overrated. It would be terrific if all we had to do is tell children they’re great and can be anything they want to be if they just try hard enough. This labelling is not harmless – it implies that if you fail it’s your fault in that you didn’t try hard enough. Parents and teachers’ perceptions of a student may be preconceived as you say but I think these perceptions are based on children’s performance. So, I don’t think that DNA testing will have major effects due to labelling.

Question 8

Does changing your behavior change your DNA?

Robert Plomin · Accepted Answer

The neat thing about inherited DNA sequence is nothing changes it from the moment you began life as a single cell. All the other trillions of cells in your body have the same DNA, which means that a baby’s DNA at birth can predict their traits as an adult.

You might be thinking about gene expression, which doesn’t change inherited DNA sequence. (This is distinction is described at length in my book, Blueprint: How DNA Makes Us Who We Are.)

Question 9

What can DNA tell you about a person?

Robert Plomin · Accepted Answer

If you are referring to DNA genotyping as in 23andMe, DNA testing can tell you with certainty about the thousands of single-gene disorders. For common disorders like heart attacks and psychological dimensions, thousands of inherited DNA differences contribute to differences between people when we aggregate these DNA differences into what is called a polygenic score. You can make a pretty good prediction of a newborn’s height from their DNA polygenic score. The strongest prediction in the behavioural sciences is a polygenic score for school performance – it accounts for about 15 percent of the differences between children in the UK at age 16 on nationwide tests of school performance.  (This is described at length in my book, Blueprint: How DNA Makes Us Who We Are.)

Robert Plomin · Answer

After my 50 years of research on this topic, I have concluded that inherited DNA differences are the major systematic force making us who we are as individuals – our personality, our mental health and illness and our mental abilities and disabilities. (This is what my book is about: Blueprint: How DNA Makes Us Who We Are. If you meant, what are the biological mechanisms by which genes influence behaviour, that’s also described in Blueprint.)

Question 10

How do our genes affect or influence our behavior?

Robert Plomin · Accepted Answer

After my 50 years of research on this topic, I have concluded that inherited DNA differences are the major systematic force making us who we are as individuals – our personality, our mental health and illness and our mental abilities and disabilities. (This is what my book is about: Blueprint: How DNA Makes Us Who We Are. If you meant, what are the biological mechanisms by which genes influence behaviour, that’s also described in Blueprint.)

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