Biogenetic Overreach

Blueprint How DNA Makes Us What We Are is the latest book by genetics researcher and author, Robert Plomin. It begins with discussions about twin and adoption studies, an area where Dr. Plomin has extensive experience as a researcher. This serves as a springboard for Plomin to discuss DNA research, particularly “polygenic scores,” for which he possesses an almost evangelical zeal. Mixing this with his own research anecdotes and theories about a self-described “DNA Revolution,” Plomin's meandering narrative is, at times, difficult to follow and has a utopian feel.

As Plomin acknowledges, much of the early DNA research related to psychological traits (and most traits in general) failed to find specific genes related to the trait in question. When such genes were found, the experiments were never replicated, creating a “replication crisis” in the field. In Dr. Plomin's view, this crisis was solved by the larger datasets now available and the polygenic score, which “predicts” the likelihood of particular traits by tallying up the number of genetic variants a person has that have been shown to correspond in some way to particular traits. I would suggest that this is a significant lowering of the bar for replication and does not eliminate the crisis.

Throughout, Plomin presents theories about genetics and psychological traits, some being current paradigms in the field, such as “polygenic inheritance,” and some being his own ideas, adding some of his own terms (“generalist genes,” “non-shared environment”). He makes little distinction between these theories and generally presents all of it as proven fact, providing limited evidence other than the above-noted twin and adoption studies. This style finds him occasionally wrestling with contradictions. The first involves an issue of the nature versus nurture argument. He notes that 50% of particular behavioral traits should be attributable to genetics based on twin studies, but largely negates specific environmental factors as c