Rebecca attended the University of California at Santa Cruz in 1990-91 where she lived in dorm 1 at Stevenson College. She studied music and participated in the dorm talent show, singing a musical comedy routine with a high school friend who joined her at UCSC. During the summer following her freshman year, Rebecca began her career modeling and did not return for her sophomore year.

She married actor John Stamos on September 19, 1998. During her marriage, she used the name Rebecca Romijn-Stamos in both her personal and professional life. The couple announced their separation on April 12, 2004, and divorced on March 1, 2005. She has since returned to using her birth name.

Romijn was asked by Elle magazine in April 2002 whether making Femme Fatale had given her any new ideas about her sexuality. She said, "You know, in my early twenties I wondered if I was interested in women and so I kind of, well ... did my homework. [Grins] And it turns out I'm pretty straight".

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