Beneath the Surface
Although people can look quite different from one another, all of us share 99.9% of the same DNA. So what makes us individuals? Our inherited differences--from our eye color to our risk for certain diseases-stem from the one tenth of one percent of human DNA that varies from person to person. Because our DNA contains more than three billion bits of information, this tiny percentage amounts to more than three million differences. Additionally, much of our individuality is not controlled by our genes, and instead develops from environmental, social and cultural influences, as well as from human behavior and thought.
Is race in our DNA?
Of all the DNA differences between any two people, the vast majority can't be predicted by racial groupings. Many African Americans are as genetically similar to white Americans as they are to natives of Africa. What about the DNA differences between "races"? Some have no effect, while others influence superficial traits like skin color and facial features. Differences of culture and society also can distinguish one group from another, but these distinctions are not rooted in biology.
Race in medicine
Medical researchers sometimes use racial categories to estimate risk for certain diseases. For example, one in 29 Americans of European descent carries a genetic mutation for cystic fibrosis, a debilitating lung disease. The mutation appears less frequently among Asian Americans (1 in 90). A child who inherits the mutation from both parents will get the disease, so researchers urge parents to consider genetic testing, especially if both parents are white. But racial categories offer only rough risk estimates for genetic diseases. The only reliable way to learn about a person's inheritance is to study his or her individual DNA.