When humans are brought into existence by the copulative act of their parents, they inherit a complete “set of instructions” (53) with which to build a body to inhabit. Edward O. Wilson presents this fact and poses a question: “to what extent does the wiring of the neurons, so undeniably encoded in the genes, preordain the directions that social development will follow?” (55). This is the proper arena in which to determine the precise limits of genetic determinism, the reality that an individual’s genetic makeup is constitutive of their existence from the first moment of life.

At one extreme would be the determinism that governs the life of a creature like the mosquito, “confined to a single channel, running from a given set of genes to the corresponding single predestined pattern of behavior” (55). The life of a mosquito is pure genetics, nothing else. At the other extreme would be a kind of angelic existence, finding no roots in the material whatsoever, an infinitely malleable existence determined by the power of will. Human nature, as experience and scientifically verifiable data show, falls in the middle of these extremes. It exhibits restricted characteristics—such as the predisposition to be right-handed, or the predisposition to become an alcoholic or develop breast cancer—but not behavior predetermined by genetics to such a degree so as to remove freedom or development.