Older sister of Christian rocker Phil Keaggy (and Glass Harp front man) Phil Keaggy.
Daughter Molly (known as Moll Anderson) was born during Kay's first marriage to a New York cosmetics executive. She is a Lifestyle Expert/Celebrity Interior Designer in Nashville, TN, with one child, a son, Michael.
As of 2002 she was living in Phoenix, AZ.
In an interview from August 14, 2018, with the Cultivated Podcast, Kay's brother, Phil Keaggy, said that Mary Ellen had died recently, at the age of 88.
Son Bill was born during Kay's second marriage to Tim Ruffalo. Bill has three daughters -- Cortney, Tiffany and Molly.