WASHINGTON -- That's how it goes with kids. You hardly notice how fast they're growing up, then suddenly big sis is nearly as tall as Mom and the little one is a tween, gently sassing Dad.On the inaugural platform again four years later, a more mature Malia Obama, 14, and Sasha, 11, smiled, sometimes giggled and chatted with their cousin, Avery Robinson, as they awaited their father's arrival. Sasha bounced on her feet a bit as if chilly; later at the parade, she danced in her seat to the beat of passing drummers. Malia, rivaling her mother's 5 feet 11 inches, looked poised in calf-high black boots. Like any girls their age, they whipped out their smartphones in the reviewing stand to take photos.Both daughters appeared relaxed and oblivious to their global TV audience, unaffected by their rare status, unfazed by the fuss over their father.Meanwhile, fashion-watchers were tweeting about the girls' coats in vibrant shades of purple. For the record, Malia wore a J. Crew ensemble and Sasha's was Kate Spade.Such attention to the Obamas' clothes, their Hawaiian vacations, their hair -- Michelle lit up Twitter last week by adding bangs -- will continue as they charge into a time of turbulence for so many American families: the teen years.In the second term, Sasha, who arrived in the White House as a second-grader, moves on to high school. She expressed her pre-teen spirit Sunday when Barack Obama took his official, nonpublic oath of office. After giving Dad a "Good job!" she added a reminder of his flubbed words four years ago. "You didn't mess up," Sasha teased the commander in chief.For Malia, the milestones to come are many. She'll be hitting the years when typical teens start driving, dating and applying to colleges. How normally can any of this go at 1600 Pennsylvania Ave.?Life in the White House is bound to feel different to a teen than it does to a second-grader.Seven-year-old Emanuel Coleman's grandmother positioned him on the steps of the National Gallery of Art to watch the swearing-in on a giant outdoor screen Monday. The Durham, N.C., boy thought life for a White House kid must be cool, because the president has "his own private limo, helicopter and lives in a really big house.""It would be fun to fly in the presidential helicopter," Emanuel enthused.Sixteen-year-old Colleen Casey isn't so sure."They have to live their life in their dad's shadow," said Casey, part of a group of Girl Scout volunteers who came to the inaugural from nearby Woodbridge, Va. "You can't be your own person."That's the struggle for White House youngsters, said author Doug Wead, who interviewed 19 sons and daughters of former presidents and wrote about them in "All the Presidents' Children.""When your mom's the first lady, and all your classmates are oohing and ahhing over her, it's hard to compete with that," Wead said. "At any given time, half the country hates your father and half the country loves him. It's hard to establish a separate identity."Just last week, the National Rifle Association referred to the Obama daughters in an ad berating their father for opposing a proposal to put armed guards in all schools, while his children get Secret Service protection. And the president's been criticized for sending Sasha and Malia to the private Sidwell Friends School.Even the great stuff -- traveling the globe, meeting rock stars, mingling with world leaders -- can go to a girl's head.Mrs. Obama says she strives to give the girls a normal life -- homecoming dances, playing basketball, trick-or-treating, slumber parties -- and also to keep them respectful, responsible and down-to-earth.There's been lots of speculation that Mrs. Obama, who turns 50 next year, may design her own transformation in the second term, when she'll be freed from worries about her husband's re-election. Will the first lady who dubbed herself "mom-in-chief" add to her portfolio of family-centered causes? The White House isn't yet saying.Some feminists want to see the Harvard Law School grad take on a more forceful public role. Not all her fans are so sure."I like the roles she's taken on with troops, with health, with children," said W. Faye Butts, 68, an enthusiastic Obama supporter who traveled from Macon, Ga., for the inaugural. No need to try to do more: "She has a family to raise. That's her first priority."Associated Press writers Richard Lardner, Matthew Barakat and Darlene Superville contributed to this report.