Carteris was born in Scottsdale, Arizona, the daughter of Marlene, a realtor, and Ernest Carteris, a restaurant owner of Jewish ancestry. She has a twin brother, James. Her parents separated six months after her birth. Carteris's mother moved with her children to San Francisco, California, where she set up a children's clothing store. While attending high school in Marin County, California, Carteris took an interest in the arts, studying ballet and performing as a mime on a European tour at sixteen years old. She graduated from Sarah Lawrence College in 1983 with a bachelor's degree in Liberal Arts.
She married Charles Isaacs, a stock broker, in 1992, and has two daughters with him named Kelsey and Mollie.
In the March 17, 2008 issue of People magazine, Carteris described an injury suffered while filming a TV movie in Vancouver, Canada, in 2006 that partially paralyzed her face and affected her speech for over six months.