The role of genes in governing behavior remains one of the most controversial topics in human biology. Early in this century, over-eager promotion of a genetic basis for behavior led to the excesses, and ultimately the horrors, of eugenics. Subsequent reactions to these excesses, both within the scientific community and society as a whole, led to a nearly complete dismissal of a role for genes in human behavior. Slowly we come back to a more balanced view. Detailed studies of the biological basis of behavior in animals, from the simplest single-celled creatures through the most complex mammals ... More

The role of genes in governing behavior remains one of the most controversial topics in human biology. Early in this century, over-eager promotion of a genetic basis for behavior led to the excesses, and ultimately the horrors, of eugenics. Subsequent reactions to these excesses, both within the scientific community and society as a whole, led to a nearly complete dismissal of a role for genes in human behavior. Slowly we come back to a more balanced view. Detailed studies of the biological basis of behavior in animals, from the simplest single-celled creatures through the most complex mammals, show that genes play an important role in guiding behavior. Studies in humans, especially those involving twins reared together or apart, indicate clearly that humans are no exception. The variability we see around us in the way humans respond in a given situation is strongly influenced by the variability in their genetic makeup. So are we powerless creations of our genes? Not at all. Guided by differing genetic makeups, we respond to our environment in different ways. But these responses, and the actions of our genes, are in turn modified by the environment itself. Behavior is the result of a balancing act between genes and the environment; between what we inherit and what we learn. To understand ourselves fully, we must understand both.