From PEOPLE Magazine Click to enlarge
Anyone who knows DeOndra Dixon knows never to challenge her to a dance battle-unless you're prepared to lose. At the sprawling L.A. home she shares with big brother Jamie Foxx and other close relatives, even famous friends like Denzel Washington and Chris Brown cede the spotlight to DeOndra when the music starts pumping. "They just watch her," says Foxx. "It's such a light." And Foxx-no slacker when it comes to wowing a crowd-admits he was handily outmatched by his sister, 27, when the two took the stage at a recent fund-raiser for the Global Down Syndrome Foundation in Denver. After Foxx performed his song "Love Brings Change" in honor of DeOndra and others with Down syndrome, the battle was on: Tossing her hair and grinning broadly, DeOndra bent back her 4'11" body nearly parallel to the floor. "I always lose the dance battle," Foxx said after the show, "because she's got the good moves."

She also has the kind of confidence that comes from the support of a loving family, including her proud, Oscar-winning big brother. "I haven't cried so much in a long time," Foxx, 43, said onstage with his sister. "These kids are so beautiful. This event allows them to shine."

DeOndra has done just that, appearing in Foxx's "Blame It" music video, dancing at the 52nd Annual Grammy Awards in front of 26 million viewers and now taking a leading role as the 2011 Ambassador for the GDS Foundation. "She is a huge part of Jamie's life," says longtime family friend Hanna Abounader. "He will be running around crazy with all these things to do, and DeOndra will walk up, grab him and hug him, and he'll stand there for 10 minutes hugging her. It brings tears to your eyes." For Foxx, it is a sibling bond that brings both rewards and challenges. "One thing people may not understand is that the person with special needs, the love that they give you is unfiltered," he says. "There is nothing in the way of them loving you and there is nothing in the way of them being upset with you either. You really get the true individual. It's challenging, but it is moments like this that make it all work. She's a superstar now."

"He works on me every day about my eating habits," breaks in DeOndra, giving her brother a sideways glance. He nods his head. "That's the challenge, because we want to extend her life. It's tough because she is grown, and she says, 'I'm eatin' it!' It's not always glory, it's not always glamorous. Sometimes it just is what it is and you have to deal with it."

For Foxx, it was love at first sight when he first held baby DeOndra-whose parents are Foxx's mother, Annette, and his stepfather George Dixon-at age 16. "We weren't trippin' on the fact that she had Down syndrome," recalls Foxx of DeOndra's chromosomal abnormality (see box). "We were trippin' on the fact that she was cute. She was this little chocolate ball." Growing up in Dallas and Foxx's hometown of Terrell, Texas, DeOndra was treated like any other member of the family. "My mom was like, 'You get on the bus with the regular kids, go to the regular school, do your thing,'" recalls the actor. "In the neighborhood, that's how it is. We just got along."

By the time DeOndra graduated from high school in 2002, Foxx had made it big in L.A. "I said, 'She's going to live with me,'" remembers Foxx, who already had his sister Deidra, 34, a hairstylist on his movies, living with him. Then the stepfather he calls Pops and his mother moved in as well. "Moving my family in with me is nothing but nonstop laughter and kickin' it," says Foxx. "And a little work."

The work comes, in part, from DeOndra, who recently left the Tierra Del Sol Foundation School, where she was employed in the school cafeteria and collected a regular paycheck. The brother and sister enjoy outings together that include birthday bashes at the Conga Room and regular movie nights. DeOndra also shares Foxx's wicked sense of humor. "I call it Ghetto Down," he explains, recalling how he questioned her about something she took from the refrigerator and she said, "'J, you know I got Down syndrome ... it just happens.'" Foxx admires her confidence and hopes it leads to more dancing on videos and maybe even a movie role. "I hope she lives the most regular, carefree and fun life," says Foxx. As for DeOndra, "I'm happy to have a big brother to count on," she says simply, "who I love every day."