Another book I picked up from the public library is Identically Different by Tim Spector.
I read the introduction and skimmed the rest of the book. It is about genetic and environmental influences, about the interaction between them, and about heritability and epigenetics. I already have a bunch of books about all of this, and so it is mostly data and ideas I’ve come across before. Still, it is always interesting to read about this subject.
What makes this book somewhat unique is the author himself. He is a research scientist who has been heavily involved in the popularizing of this field. According to the book, he has changed his views in recent years. A revolutionary paradigm shift is happening right now, largely because of new research that is challenging old theories. It’s nice to see that established scientists can and do change their minds, rather than merely old scientists dying and younger scientists replacing them with new perspectives.
Here is from the introduction to this book:
“Until three years ago I was one of the many scientists who took the gene-centric view of the universe for granted. I had spent the last 17 years producing hundreds of twin studies trying to convince a sceptical public and scientific world that virtually every trait and disease had a major genetic influence. My colleagues and I around the world were largely successful in this, and the prospect of finding the genes underlying most diseases looked increasingly certain. But I had a nagging doubt that we were missing something. [ . . . ]
“However, despite the extensive list of successes, a few signs were emerging that the paradigm was wrong. Most of the gene discoveries for common diseases turned out to be interesting in terms of biology, but the more we discovered the less useful each new gene became in accounting for the disease, since each gene is of tiny individual effect. For example, the 30 or so genes discovered for obesity, even when combined, account for only 2 per cent of the disease.
“This was frustrating to all of us working in the field, as it meant that each common disease was contolled not by one gene but by hundreds or even thousands of genes. This would require teams from many countries to combine forces and perform studies of tens, and sometimes hundreds of thousands, of subjects in order to find these tiny effects. Another consequence was that for common diseases (unlike rare monogenic diseases) these gene tests were pretty useless for prediction [ . . . ]
“While hundreds of recent gene discoveries have given us great insights into new disease mechanisms and possible drug targets, the common genes found to date usually account only for less than 5 per cent of the genetic influence. Exactly where the missing 95 per cent comes from is a mystery that is perplexing the field. Most scientists agree that we simply aren’t smart enough to realize what we don’t know. [ . . . ]
“There are few if any examples of environmental factors without a genetic component, and conversely genes don’t work alone and are usually dependent on the cells they live in and their environments. So in a world where hundreds of genes are working together to influence a trait or disease, the old distinction between nature and nurture is simply no longer relevant.”
The introduction is worthy of being read on its own. It could easily be read as a stand-alone essay.
The rest of the book deals with specific issues about traits and diseases. It is all standard analysis for this type of book, but it is useful as a fairly recent review of the research as it was published in 2012. The research is constantly changing which means books quickly become less relevant. As the author points out, “Most scientists agree that we simply aren’t smart enough to realize what we don’t know.” There are more questions than answers at this point. So, any theory is largely speculation, to varying degrees of probability not easily calculated.
I did have one problem with the book. The author seems to still be trapped within the terminological constraints of the old paradigm of nature versus nurture. He constantly refers to percentages of influences being genetic or environmental. Such claims are meaningless. The author speaks of the problem, but doesn’t get to the core issue.
He argues that the research shows that only a tiny percentage of influence is genetics alone and that only a tiny percentage is environment alone. I suspect, to be most accurate, absolutely zero percent of genetics and environment ever acts alone. They are inseparable. Genetics never exists or acts outside of an environment. And an environment that exists without genetics would be an environment that is irrelevant to human biology and behavior.
As David Shenk explains, in The Genius in All of Us, “heritability estimates are statistical phantoms; they detect something in populations that simply does not exist in actual biology.” The larger context of that quote can be found in a previous post of mine, along with quoted material from a bunch of other books. Also, scientific commentary can be found in another of my posts as well.
The paradigm that needs to change isn’t just about data and theory, but also about the terminological and conceptual framework we use to discuss data and theory.