Scientists Seek Genetic Clues To Asthma's Toll On Black Children

Zunika Crenshaw cringes as a tire swing whips her children around in circles just a little too fast. It's a sunny afternoon in the park, in Pleasanton, Calif. As her children play, she keeps a close watch on their breathing.

She says asthma is in her genes.

"You have a family, a person who has four kids, and all of them have it, including me," she says. "And then my mom has it, and my sister's two kids."