Nancy Davis' mother, Edie, was a retired actress married for the second time to Loyal Davis, a well known Chicago doctor. Nancy was the daughter of Edie and her first husband.
Edie hosted actors/actresses who visited Chicago, especially Spencer Tracy and even Mary Martin and eventually Yul Brynner.
Somehow, Nancy Davis was signed by MGM studios in California. legendary director filmed her screen test and declared she had no talent, But, she did have MGM star Spencer Tracy on her side (Nancy had small roles on Broadway thanks to Martin.)
Years later Nancy Reagan laughed when she leaned MGM signed her rather than Marilyn Monroe.
From a new bio of Mrs. Reagan by Karen Tumulty