Thirty-eight years after Christie Brinkley first posed for the cover of the Sports Illustrated Swimsuit Issue, she's back for another spread--this time accompanied by her daughters. At age 63, Brinkley rocks some skimpy suits alongside 18-year-old Sailor Brinkley Cook and 31-year-old Alexa Ray Joel in a new spread for the publication. "In a country that's very ageist, people love to put you in little boxes," Brinkley tells People. "Women feel very limited by their numbers. On a personal level, I thought, if I can pull this off, I think it will help redefine those numbers and remove some of the fear of aging." The issue hits stands Wednesday.