Most people thought that Marilyn was playing herself in roles like she had in Show Business, Monkey Business, or Gentlemen Prefer Blondes. Viewers based this opinion upon the seeming lack of skill that her roles required and upon the similarity between these characters and the public image she projected during the first half of her career.
However, most of the roles that were given to Marilyn were the opposite of her personality. Marilyn was not a dumb blond. She was thoughtful and determined and a workaholic. She insisted on perfection from herself in her scenes. On the set, Marilyn was her own slave driver. Off the set, over her lifetime, she allowed herself very few vacations. She appeared where she had to appear at the request of the studio, but she was not a social butterfly and stayed too busy to do much dating. Although she left high school after the eleventh grade, and although there were gaps in her general knowledge, she had a good academic record and throughout her life was a voracious reader. Marilyn’s constant reading only seemed to earn her criticism and ridicule. The real Marilyn thought to be the phony one.
-My Sister Marilyn by Berniece Baker Miracle.