JFK Jr. was the ‘only one’ who understood Caroline Kennedy’s loss (Exclusive)

On Monday, January 5, generations of the Kennedy family said goodbye at Tatiana Celia Kennedy Schlossberg’s funeral, but the memory of the family’s private grief and public loss was ever present.

“Every time a Kennedy dies, and certainly when they die tragically, we remember others,” says presidential historian Stephen M. Gillon. “You can’t look at this in isolation. It’s just a reminder of this terrible burden that this family has had to carry.”

In November, Tatiana, 35, the daughter of Caroline Kennedy, 68, and Ed Schlossberg, 80, revealed her rare cancer diagnosis for the first time in a beautifully written New Yorker essay.

Five weeks later she was gone. “Our beautiful Tatiana passed away this morning. She will always be in our hearts,” a family statement posted by the JFK Library on Dec. 30 read.

The grief of this famous political dynasty is unimaginable. It is not only the loss of a vibrant young woman who leaves behind her husband of nine years, George Moran, and two young children, Edwin, three, and 18 months, but also a reminder of the personal suffering of her mother, Caroline.

“The contrast between this incredibly private person and this very public tragedy is striking,” says Gillon, who studies the Kennedy family and is the author of America’s Reluctant Prince, a biography of John F. Kennedy Jr.

Friends have long said that if anyone could understand her, it was her brother John, who died aged 38 when the plane he was piloting crashed in 1999, his wife Carolyn Bessette, 33, and sister Lauren, 34.

“Caroline suffered the same loss as John, except that she lost her brother,” Gillon says.

Gillon begins with the 1963 assassination of Caroline’s father, President John F. Kennedy, and puts it into perspective.

“She was old enough to know what happened, to know he was gone. She was old enough to recognize her mother’s grief,” he says. “Robert Kennedy became a father figure to her and John, but was assassinated in 1968.”

Recording her grief, Gillon continued: “Her mother (Jacqueline Kennedy Onassis) died at the relatively young age of 64, and in 1999 she lost her brother. It was just a series of terrible personal tragedies that culminated in her daughter’s death,” adding that Tatiana’s death “might be the most painful of them all.”

“In many ways, she reminds me of her mother,” Gillon added. “However, her mother was more public than Caroline.”

Never miss a news. Sign up for PEOPLE’s free daily newsletter to stay up to date on what PEOPLE has to offer.

Still, in many ways, Caroline, the daughter of a beloved president turned stalwart American diplomat, remains an enigma.

“We can document the various tragedies in her life, but what we don’t know is how she coped with those events,” says Gillon. “She never talked about it, at least not publicly. All we can infer based on family tradition is that she faces death through determination, just as the Kennedys always face death.”