Grace Wilsey couldn’t cry. As a baby, she would lie limp in her parents’ arms, staring blankly into the distance. Her seizures wouldn’t stop and medical tests showed signs of liver damage. This was all before her second birthday. Grace’s parents were beside themselves, as any parent would be. They traveled the country visiting specialists. They ran numerous tests, but no one could diagnose Grace’s condition. “We’ve probably seen over 100 doctors,” Grace’s father said in 2014 when Grace’s symptoms were discovered. None of them could provide an explanation. Then, when their daughter turned two years old, the Wilseys tried...