Translation 2006 Spring

This article was a translation of a Chinese article.

Heredity or environment: which is stronger? In a way, the potentials which a person is born with determine in some way what he will do in life. Therefore heredity is fate, a kind of predestination. However, genes do not work in a vacuum; as soon as we begin considering the role that they play in the development of the individual, we see that there can be no development without the interacting environment. No characteristic is caused exclusively by either environment or genes.

The relative effects of heredity and environment are most clearly observable in identical twins. Most identical twins are raised together and are remarkably alike in both appearance and behavior. These cases demonstrate that individuals with the same genes, when raised in the same environment, will respond to it in much the same way. They do not indicate what would happen if these identical individuals were raised separately.

A number of studies have been made of identical twins raised apart. The twins who were the subjects of these studies lived in America, were raised in much the same physical environments, and experienced much the same nutritional histories. Therefore, as one might expect, they maintained the closest resemblance to each other in physical appearance, height, and weight. Exceptions occurred when one twin had developed a rather severe illness and the other had not; but on the whole everyone is impressed by the great psychological and physical likenesses that exist between identical twins, even those who have been separated from infancy.