January Jones was born on January 5, 1978 in Sioux Falls, South Dakota. She is named after January Wayne, a character in Jacqueline Susann's potboiler novel turned film, Once Is Not Enough. She is the daughter of Karen Cox, a store manager; and Marvin Jones, a gym teacher and fitness director. She is of Czech, Danish, English, Welsh, and German descent. She has two sisters, Jacey and Jina.