Beyond Nature and Nurture. By: Robinson, Gene E., Science, 00368075,
4/16/2004, Vol. 304, Issue 5669
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The horns of a dilemma
are usually on the same bull (1).
When it comes to behavior, the nature-nurture controversy has not disappeared. The
public is leery of attributing behavioral influence to DNA rather than to the environment
and free will; worries abound over the ethical implications of biological determinism.
Many social and behavioral scientists are skeptical as well, either because the concept of
"DNA as destiny" does not jibe with their understanding of the dynamic nature of
behavior or because they consider human behavior to be much more complex than that of
animals studied from a genetic perspective. By contrast, biologists have long accepted
that genes, the environment, and interactions between them affect behavioral variation.
Traditionally, behavioral variation has been partitioned using statistical analysis into
genetic (G), environmental (E), and G x E components, an approach that began long
before the advent of molecular biology. This retains the flavor of the nature-nurture
dichotomy, which influences how research in this field is interpreted. Fortunately, we can
now study genes in enough detail to move beyond the nature-nurture debate. It is now
clear that DNA is both inherited and environmentally responsive.
Behavior is orchestrated by an interplay between inherited and environmental influences
acting on the same substrate, the genome (see the figure). For behavior, gene expression
in the brain is the initial readout of the interaction between hereditary and environmental
information. Inherited influences ("nature") include variations (polymorphisms) in DNA
sequence transmitted from generation to generation over an evolutionary time scale.
DNA polymorphisms can affect protein activity (sometimes via posttranslational
mechanisms) and gene expression in the brain: when, where, and how much of each
protein is produced. The environment ("nurture") also influences gene expression in the
brain during the lifetime of an individual (
). Environmental effects occur over
developmental and physiological time scales. Gene expression in the brain constitutes the
first measurable indicator of the interaction between the genome and the environment.
Until recently, this "first phenotype" was not easy to study. However, it is now possible