Katelyn Maura Salmont was born on September 7, 1986 in Southern California. She was born with a genetic lung condition called cystic fibrosis. By 2005, the CF had done so much damage to her lungs that she had to undergo a double lung transplant.
She is the stepsister of Mackenzie Rosman, and has been ever since Mackenzie, her mother, and her brother moved to L.A. in the mid-1990's and then Katelyn's father married Mackenzie's mother.
Katelyn has starred in two episodes of "7th Heaven". The first episode aired in January 2003, and was called "Back in the Saddle
… More Again," where Katelyn played a friend of Ruthie's and Ruthie, along with the viewers of "7th Heaven," learned about CF. The second episode aired around Christmas 2005, and Katelyn returned to talk about the new lungs she had gotten for Christmas, and her double-lung transplant.