When she was six years old, she was chosen as the poster child for the non-profit organization March of Dimes, due to a congenital birth defect that resulted in the amputation of her left leg.

[1] She has written two memoirs, one that presents her life as an amputee and the other that tells the story of the birth of her son Ronan Christopher Louis and his diagnosis of Tay–Sachs disease.

Rapp was raised in Laramie, Wyoming; Kearney, Nebraska; and Denver, Colorado; by her father, a Lutheran pastor, and her mother, a school nurse.

[3] She and her third husband, Kent Black, lived in Madrid, New Mexico,[4] before moving to Redlands, California, where they reside with their daughter, Charlotte (Charlie).

Before entering divinity school, Rapp worked in Geneva, Switzerland; Namibia; Hong Kong and Bangkok, Thailand for the Women's Desk of the Lutheran World Federation, an international relief organization.