In the original run of Katy Keene stories ending in the 1960s, Katy's younger sister "Sis" was a young child. In the 1980s revival of Katy, Sis was aged to a young teenager, bespectacled and redheaded. Their parents had died and Katy Keene acted as a surrogate parent to her sister. She was still called "Sis," though the writers entertained giving her an actual name as "Melissa."In the 2000s revival of Katy, Sis was finally christened Mackenzie Keene. Most elements of the 1980s incarnation were kept, other than dropping the glasses and changing her hair color from red to light brown.