Tatiana and Jack Schlossberg’s special sibling bond

Jack Schlossberg shared a close bond with his older sister, Tatiana Schlossberg, until her death on Dec. 30.

Tatiana passed away at the age of 35 on Tuesday after a battle with acute myeloid leukemia.

“Our beautiful Tatiana passed away this morning,” the JFK Library Foundation shared via Instagram, adding, “She will always be in our hearts.”

The message was signed, “George, Edwin and Josephine Moran … Ed, Caroline, Jack, Rose and Rory.”

Tatiana shared her devastating diagnosis in a moving essay in the New Yorker in November. At the time, she shared that her terminal condition was discovered in May 2024, and that doctors told her she had a year to live.

The diagnosis came following the arrival of her second child with husband George Moran.

Jack — who is running for Congress — supported her in a powerful Instagram Story shortly thereafter. The son of Caroline Kennedy and Edwin Schlossberg shared a photo of a gravel-paved road, and an image of a bright blue sky.

“Life is short — let it rip,” he wrote atop the photos last month. He also shared excerpts from his sister’s emotional essay, “A Battle With My Blood.”

The late author acknowledged both her older sister, Rose, and her brother in the essay, as well as her husband. “George did everything for me that he possibly could,” she wrote of her spouse. “He talked to all the doctors and insurance people that I didn’t want to talk to; he slept on the floor of the hospital.”

“My parents and my brother and sister, too, have been raising my children and sitting in my various hospital rooms almost every day for the last year and a half,” she continued.

“They have held my hand unflinchingly while I have suffered, trying not to show their pain and sadness in order to protect me from it. This has been a great gift, even though I feel their pain every day.”

Tatiana noted in the heartbreaking essay that she had “tried to be a good student and a good sister and a good daughter” throughout her life.

The siblings — raised alongside older sister Rose as the only three grandchildren of the late John F. Kennedy and Jaqueline Kennedy Onassis — had plenty in common.

Both attended Yale University, where Jack studied history with a focus on Japan, and Tatiana served as editor-in-chief of the Yale Herald.

Tatiana also shared her brother’s interest in history — she would go on to receive a master’s degree in United States history from the University of Oxford in England.

It was a passion they both shared with their late grandparents, she once shared with Vanity Fair.

“My grandparents, both of them, from what I understand, because I didn’t really know them, loved history and reading about history,” she said in 2019.

“And that’s kind of how I’ve connected with them, by studying them and their time, but also the eras and patterns that fascinated them, and imagining where we would disagree. That’s an important way for me personally to connect with my family legacy.”

Though Tatiana has passed, Jack will continue to nurture that family legacy with the two children she shared with Moran.

“I have a new nephew,” Jack said during a Today show appearance in 2022.  “It’s a boy. His name is Edwin but I like to call him Jack.”