Jean Kasem was one of five children, with siblings Jeanette, Shirley, Joan and Tommy Thompson, of Irene Celia Thompson (1919-2008) and Herbert Owens Thompson Sr. (deceased). She lived in Portsmouth, New Hampshire, before her civil-servant father moved the family to Guam in 1963 to help stop her recurring pneumonia. She attended the University of Guam at age 16, but after marrying a U.S. Navy lieutenant when she was 17, she left to work as a waitress and saleswoman on U.S. military bases throughout the Pacific Ocean to which her husband was posted. The marriage lasted six years. Kasem then moved to California and unsuccessfully attempted to find work in broadcast journalism. Frustrated, she joined an acting workshop and soon found roles on such TV series as Matt Houston, Fantasy Island and Alice.
She has been married to radio personality Casey Kasem since 1980 and they have one child together, Liberty Jean Kasem.
In 1989, Casey Kasem purchased a house built in 1954 and located at 138 North Mapleton Drive, previously owned by developer Abraham M. Lurie, as a birthday present for her. In 2013, he listed it for US$43 million.
In October 2013, Kerri Kasem, one of Casey Kasem's three children from his first marriage, said her father was suffering from Parkinson's disease. On October 1, Kerri Kasem, her siblings and Casey Kasem's brother protested outside Casey and Jean Kasem's home, saying Jean Kasem had been preventing contact with Casey Kasem for three months. On October 7, Julie Kasem and her husband, Dr. Jamil Aboulhosn, filed a conservatorship petition to place Casey Kasem under their care.
^Fitzpatrick, Laura (July 07, 2009). "Radio Host Casey Kasem". Time. Retrieved October 1, 2013. "Married his current wife, Jean ... in 1980. ... In 1990, after suffering eight miscarriages, the couple had a daughter, Liberty Jean Kasem."