Watch: Jack Schlossberg Supports Sister Tatiana Schlossberg After Terminal Cancer DiagnosisJack Schlossberg is standing by his family. After his sister Tatiana Schlossberg shared her terminal cancer diagnosis, the son of Caroline Kennedy and Edwin Schlossberg offered his support on social media. In a series of posts on his Instagram Stories Nov. 22, Jack, 32, reposted excerpts from Tatiana's New Yorker essay, in which she detailed being diagnosed with acute myeloid leukemia after giving birth to her second baby with husband George Moran in May 2024.