As a kid, she raised money to cure cystic fibrosis. Now she’s the CEO of a $2.6 billion genetic testing company

When Katherine Stueland was 11 years old, she went to a reunion for her mother's branch of the family tree and learned that multiple cousins had cystic fibrosis.

Stueland didn't know what it meant for her or her immediate family. So she hit the books.

"There was one written by sportswriter Frank DeFord"—Alex: The Life of a Child—"about his daughter having cystic fibrosis," she tells Fortune. "I devoured it and decided I was going to change the world. I ended up raising $1,500...