Princesses Beatrice and Eugenie Have Had a 'Stability That William and Harry Have Found Painfully Lacking in Their Lives'

Like their cousins Prince William and Prince Harry, Princess Beatrice and Princess Eugenie experienced the pain and childhood upheaval of their parents’ very public divorce.

But their family healed, and the young women and their parents — Prince Andrew and Sarah Ferguson — have developed a close family unit that has helped Queen Elizabeth’s granddaughters thrive.

Although Fergie and Andrew divorced in 1996, she still has rooms at the family home, Royal Lodge, and she has regularly said she and Andrew are the “happiest divorced couple” in the world.

“Beatrice and Eugenie have had a stability that William and Harry have found painfully lacking in their lives,” says Ingrid Seward in this week’s issue of PEOPLE. “Although their early childhood was not good, those girls have had a very secure upbringing.”

Seward, who wrote a biography of Ferguson, adds, “The girls love that their parents get on so well.”

RELATED: Sister Act! Princess Eugenie and Princess Beatrice’s Royal Relationship Through the Years

Of course, for William, who turns 37 on Friday, and Harry, 34, their sadness over their own parents’ divorce was compounded by the fact that their mother, Princess Diana, died in a 1997 car crash just as she was starting to create a new contentment in her post-divorce life.

• Can’t get enough of PEOPLE’s Royals coverage? Sign up for our newsletter to get the latest updates on Kate Middleton, Meghan Markle and more!

Unlike William and Harry, Beatrice, 30, and Eugenie, 29 — who joined the Queen at Royal Ascot on Tuesday — have made careers in the real world of business, while continuing to contribute to causes close to their heart and pitching in to support the Queen and their father’s royal duties.

“They are independent, working women but are also aware of their position and where they can help,” says a family friend.