Jessica Alba refuses to go fully nude.

Even though the 33 year-old reprises her role as stripper Nancy Callahan in the hotly anticipated sequel 'Sin City: A Dame To Kill For', audiences will not see her bare all.

This is due to a no-nudity clause Alba adds to her contract when signing on to star in a movie.

The Hollywood actress explained her reasons in the June issue of Glamour magazine, in which she showed hardly any flesh when featuring on the front cover.

"I don't want my grandparents to see my boobs. That's it," Alba explained to the mag. "It would be weird at Christmas. And, I mean, really, if you look at the movies I have done, getting naked would never 'elevate' the picture."

Alba, who was raised catholic, also opened up about her current relationship with husband Cash Warren, 35, and her previous engagement to NCIS star Michael Weatherly, with whom she lost her virginity to at 19 years-old.

"Relationships can be tough," Ms Alba said. "With Michael, I didn't have a voice yet, and he was so much older," Weatherly was 12 years her senior.

Fast forward 14 years later and the 'Fantastic Four' actress has been happily married with Warren for six years, with whom she shares two daughters.

But Alba revealed due to being brought up to be "fiercely independent," she first found it difficult to rely on other people, especially men.

MORE: Jessica Alba Doesn't Care About Fantastic Four Role 

"Where I was from, you had to answer to a man if he was the breadwinner. My mom told me that didn't need to be the case for me - I didn't need to rely on a man," she said. "She taught me how to hustle. I was determined to be financially independent. So I started making my own money when I was 12 [with acting]. That was freedom."

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On top of becoming a highly successful actress, Jessica now owns her own lifestyle brand which she discusses more in the issue, as well as her views on feminism and many more topics.

Jessica Alba
Alba and Warren have been happily married for six years