Though there are no traditional characters in Nature via Nurture, Ridley refers to several seminal scientific thinkers throughout.

Noam Chomsky

In chapter 2, "A Plethora of Instincts"; chapter 5, "Genes in the Fourth Dimension"; and chapter 9, "The Seven Meanings of 'Gene,'" Ridley references famed linguist Noam Chomsky, one of the leading proponents of the "nature" side of the debate. Ridley asserts that "nativism" was all but eclipsed until 1958, when Chomsky argued for what would become known as the LAD: the Language Acquisition Device. Chomsky argued that children possess innate rules—such as syntax—to which language is fitted. Thus, it would be erroneous to assume that we learn language wholly from experience. These findings were revolutionary, for the notion of tabula rasa, or blank state, had been widely regarded as true at that time.

Charles Darwin

Charles Darwin is alluded to in almost all of the chapters in Nature via Nurture. In chapter 1, "The Paragon of Animals," Ridley relates Darwin's account of the hunter-gatherer tribes of Tierra del Fuego and his subsequent first encounter with a great ape in the London Zoo, as both these experiences would be instrumental in his formation of what we now know as the theory of natural selection. Darwinian similarity, which is a concept Ridley would reiterate throughout the book, is the merely qualitative degree of difference between ape and man. Darwinism is still a gigantic school of thought in modern science, and other key figures in Nature via Nurture are often contrasted with Charles Darwin and his followers.

Richard Dawkins

Chapter 5, "Genes in the Fourth Dimension," opens with a quotation from Richard Dawkins:

We cannot now break the cake into its component crumbs and say: this crumb corresponds to the first word in the recipe; this crumb corresponds to the second word in the recipe.

This is in reference to the genome and how the concept of it is often wildly misunderstood. Ridley often refers to Dawkins in the context of the gene and gene development. In chapter 9, "The Seven Meanings of 'Gene,'" Ridley applauds Dawkins' infamous concept of the so-called "selfish gene" and uses this to illustrate that genes possess the capability to evolve specifically to our immediate needs.

Ivan Pavlov

Ridley references Ivan Pavlov throughout Nature via Nurture but discusses him at length in chapter 7, "Learning Lessons." Pavlov's experiments, which involved the study of dogs' salivation reflex to food, would result in what is now known as classical conditioning. This discovery of Pavlov was vital to the "nature versus nurture" debate, for it could now be argued that instinct is merely knowledge unconsciously formed through associations or repeat experiences. Ridley, however, adds that modern scientists have revised Pavlov's theories—that surprise registers to the brain as more informative than predictability. This means, therefore, that active learning is contingent not on stimulus or reward but rather on "prediction errors."

B. F. Skinner

Ridley refers to Skinner in chapter 1, "Paragon of Animals"; chapter 5, "Genes in the Fourth Dimension"; chapter 8, "Conundrums of Culture"; and chapter 10, "A Budget of Paradoxical Morals." Ridley discusses him at length, however, in chapter 7, "Learning Lessons." There, Ridley asserts that Skinner revolutionized psychology with the formation of the Skinner box: the organism as a black box that need not be opened. This organism merely processes signals from the environment into an appropriate response, adding nothing from its innate knowledge. This means, for example, that we are conditioned even more effectively with an absolutely random system of punishment and reward. This is what we know now today as operant conditioning.