Children who are black or poor get asthma twice as often as other children, a University of Rochester pediatrics professor has found.

"What is thought of as a genetic disease actually has a significant environmental component," says Dr. Michael Weitzman. While Weitzman does not discount the role of genetics, he does note that certain environmental "triggers" can determine who develops the disease.Chief among these "triggers" is the mother's smoking. Other conditions that increase risk of asthma include teenage pregnancy, low birth weight and crowded living conditions.