“Blueprint: How DNA Makes Us Who We Are” by Robert Plomin

I first read this when it came out in 2018, but did so again this week in a version which included a more recent appendix in which the author answers some of the criticisms that reviewers made in respect of the original edition.

Robert Plomin is a pioneering geneticist who works at Kings College in London, so he really knows what he is talking about. And while a general reader such as myself will inevitably find some of the more scientifically sophisticated passages tough-going, this is for the most part a wonderfully accessible account of current developments in this fascinating scientific field.

The book is divided into two main parts. The first explains how behavioural geneticists over recent decades have gone about their work investigating how much of personality and how many of our personal characteristics, personal preferences and dispositions are inherited from our parents. The answer is a huge amount. It varies depending on the construct, but around half seems to be explained by our DNA and the remaining half by environmental factors and upbringing etc. The major studies that consistently demonstrate that this is the case include studying children who are adopted out of their original families and comparing them both with their adopted and birth parents. They tend to have just as much, if not more, in common with the latter as they do with the former. The other major types of studies involve pairs of twins, and particularly comparisons between the attributes of identical twins (with the same shared DNA) and non-identical twins who share an identical upbringing, but only 50% of their DNA. Sometimes studies have been conducted using twins who have been separated at birth and brought up in different adoptive families. It is all extraordinarily interesting.

Some of the points Plomin makes seem to me to amount mostly to science proving what we all know from our own personal experiences to be true, namely that we inherit a lot of personal attributes from our parents and that this extends way beyond how we look physically. This accords with the observations we make all the time within families, but Robert Plomin is right to point out that for many academics, saying such things has for much of the past hundred years been anathema and that he has been heavily criticised for questioning their assumptions.

This is all particularly interesting for me because much of my professional life has been spent dwelling alongside sociologists, for whom the mantra ‘everything is socially constructed’ is the starting point for all research. My doctorate focused on aspects of the work of the great French sociologist Pierre Bourdieu whose work I consider to be outstanding and of enormous help when looking to explain why some people are more successful than others in professional life. I was though determined to critique his thinking and not simply to replicate aspects of it, and to that end read Plomin’s work as well as other books and papers on genetics. I then wrote passages arguing that Bourdieu’s world view was incomplete because of his determination not to acknowledge or include in his analysis considerations of biology and inherited characteristics. My supervisor warned me that one of the sociologists who would be conducting my viva might not take too kindly to this aspect of my argument. So I spent two weeks preparing answers to any challenge to my view that nurture and nature both play a part in determining who does well in their careers. In the event it was not an issue. She just said that she was sure I was right about that, and went on to discuss other issues.

The second part of the book is more focused on DNA sequencing and the way that this can be used to make predictions about how people will be disposed to behave. This was more future-focused, and while really interesting in its conclusions, for me not quite as engaging as the first part.

Overall though the book is really well-worth reading, particularly the sections on what Plomin calls ‘the nature of nurture’ by which he means our tendency to react to social situations, including those we encounter during our upbringing, according to inherited preferences and dispositions. Some of us, for example, are naturally more shy, or robust, or generous than others. And this determines in part how we respond to situations. Different people act differently when confronted with similar challenges. It is thus inaccurate always to think in terms of nature and nurture as being entirely separate from one another. It is all mixed up. Robert Plomin makes it all very clear and understandable.