Despite the formal settings she’s often placed in, Princess Charlotte remains true to herself. "She’s a natural and has taken to royal events like a duck to water," a palace insider tells PEOPLE in this week's exclusive cover story as Prince William and Kate Middleton's daughter turns 10. Childrenswear designer Amaia Arrieta, who has dressed Charlotte since babyhood and has met her several times, calls Charlotte "a caring and determined little girl" with a personality very much like Kate’s. "She is sweet but also has her own opinions," Arrieta says. Princess Charlotte's public appear-ances often capture a poised, polished young royal and she held her own on May 5 on the Buckingham Palace balcony to commemorate VE Day, standing with calm composure. "It’s truly her personality — it’s not forced," says Arrieta. "She looks very confident and at ease with herself and the environment she’s in. The maturity that comes with that responsibility — she seems to nail it every time." At home in Adelaide Cottage, Princess Kate has said Charlotte is known as "the one in charge." Movie nights, homemade pizzas and cake decorating are regular rituals, and the young princess isn’t afraid to assert herself. She’s also known for keeping her brothers Prince George, 11, and Prince Louis, 7 in line during official events — whispering reminders, straightening postures and nudging them at the right moments. At Queen Elizabeth's funeral, she discreetly told George when to bow. "You can definitely see traits of her great-grandmother," says royal biographer Robert Hardman, author of The Making of a King. "The practical common sense — not camera--grabbing but solid and responsible." The Princess of Wales has long been intentional about how she’s raising her three children with a balance of duty and normalcy. "Kate has the reins of power in a very subtle way. She has very strong views," says says royal author Ingrid Seward — an effort perhaps most visible in Charlotte. Like her great-aunt Princess Anne, who is often dubbed the "hardest-working royal," Charlotte already seems to grasp the rhythm of royal life. With windswept hair, a $50 camouflage jacket and sporty backpack, Princess Charlotte beamed into her mother’s iPhone camera during a family hike in Cumbria in northwest England earlier this year. Captured by Princess Kate against the rolling hills of the Lake District, the image marked Charlotte’s 10th birthday on May 2 — and signaled a turning point. Gone were the formal dresses and cardigans of birthdays past as the confident, adventurous young girl basked in her element. "She is quite a strong character," says a palace insider, "almost wise beyond her years." Can't get enough of PEOPLE's Royals coverage? Sign up for our free Royals newsletter to get the latest updates on Kate Middleton, Meghan Markle and more! Like her mother, who spent childhood holidays in those same hills, Charlotte thrives outdoors — whether scrambling up trails or hunting spiders in the garden. The Princess of Wales, 43, who recently shared how nature has become a refuge during her cancer recovery, has passed on that love to her only daughter. After a difficult year for the Wales family, the birthday photo told its own quiet story of resilience, joy and a young princess coming into ​​her own, with muddy boots and a fierce spirit. Whether playing soccer, attending Wimbledon or hitting a bull’s-eye at archery, Charlotte "is very much in Kate’s mold, competitive as well," says Nigel Gillingham, Rugby Football Union president.