Magazine article Issues in Science and Technology

Hardwired

Magazine article Issues in Science and Technology

Hardwired

Article excerpt

Blueprint: How DNA Makes Us Who We Are by Robert Plomin. Cambridge, MA: MIT Press, 2018, 280 pp..

Adding to a prolific career of scientific writing, the psychologist and geneticist Robert Plomin has produced an extremely readable and interesting book about the role of genetics in our lives. Blueprint: How DNA Makes Us Who We Are is part scientific memoir, part summary of the current state of the art of behavior genetics, and part introduction of the field to the layperson. In it, Plomin uses highly accessible terminology to explain complicated concepts of inheritance and genetic influences on various human behaviors, as well as the ostensible role of environmental influences. "The main message of Blueprint" Plomin writes, "is that genes are the major systematic force in children's development." In other words, the part of behavior that is predictable is primarily a function of DNA rather than environmental influences that are shared by members of a family.

Plomin introduces this important idea in the book's prologue, which delivers an overview of the topic of inheritance and DNA. The rest of the book provides his evidence to support this strong--and controversial--statement of the primary importance of genotype for explaining most of human behavior. Plomin uses data from his own famous twin studies as well as from the newest big data sources of genome-wide association studies (GWAS), which examine the whole genome across many people to discover small genetic variations that are associated with particular behaviors or diseases, to demonstrate the predictability of behavior from compilations of genes.

There are two primary lessons to be learned from Blueprint. The first is that, according to Plomin, "genetic research has told us as much about the environment as it has about genetics." Initially, psychologists believed that most of the environmental measures they assessed, such as the home situation, parenting behaviors, and cultural differences, were causally related to behaviors. However, exploring relations between environment and behaviors in genetically informative ways, such as using twin and adoption studies, has led scientists to realize that most of these "predictions" are in fact correlations. That is, although parenting may be related to children's problem behaviors, this relationship is primarily a function of parents' and children's shared genes, not shared environment. This is a critical point that Plomin makes throughout the book.

As Plomin notes, because of our genetic differences, we each have different life experiences. Thus, parenting styles can have different effects on siblings because they may have genetically different temperaments. This is called gene-environment interaction, and it is an essential aspect of how both genes and environment lead to individual differences in behaviors.

Relatedly, correlations between our genes and our environment occur for several different reasons. One of these is that we evoke reactions from those around us based in part on our genetic makeup (this is called evocative gene-environment correlation). Another is "niche-picking," which refers to choosing to put ourselves in environments that fit us, in part as a function of our own genetic makeup (this is called active gene-environment correlation). For these reasons, we actually express our genetic potential more and more as we age, an important point that, Plomin says, makes us appear to become more like our parents as we grow older. Becoming more like our parents is primarily a function of shared genes, although it also reflects being more in environments that reflect or amplify our genetic potential over time.

The second important lesson in Blueprint is that scientists now have access to an exciting new methodology that allows much more successful prediction of behaviors from genetic information. This new tool is the creation of polygenic risk scores, which has become possible because of the increasing number of genetic studies being performed around the world. …

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