Michael Douglas's 'birthday sister' remark for Catherine Zeta-Jones draws mixed reactions

Michael Douglas sparked a social-media moment on Thursday after referring to his wife, Catherine Zeta-Jones, as his “birthday sister” in a birthday tribute on Instagram. The 81-year-old actor and the 56-year-old actress both celebrate Sept. 25, a fact they highlighted as they posted messages to one another on the occasion of their shared birthday and of Douglas’s 81st year.

In the post, Douglas wrote alongside a golf selfie: “To my birthday sister—what a joy celebrating another year with you!,” followed by, “Congratulations on your spectacular game at the Celebrity Ryder Cup,” and a final line, “Happy Birthday to the love of my life @catherinezetajones ❤️ .” The caption quickly drew attention because fans noted the apparent mix-up between a spouse and a sister, prompting questions about the terminology in the comments.

Catherine Zeta-Jones responded with her own Instagram tribute, sharing throwback photos of the couple and writing, “Happy Birthday Michael! Sharing this special day with you is once in a lifetime!😘.” Their daughter, 22-year-old Carys, followed with a message of celebration for her parents: “September 25th 🤍Happy Birthday Mom and Dadda!!” alongside a photo of Douglas holding both her and her mother’s hands. The family’s public posts come as the couple, who married in November 2000, mark a milestone of a long-running partnership that has produced two biological children, Dylan (25) and Carys (22).

Douglas has a son, Cameron, 46, from his previous marriage to Diandra Luker. The broader family dynamic has been checked with additional context in recent interviews; last month Zeta-Jones spoke with the Sunday Times about sharing a birthday with Douglas and about their personalities alike. “We respect our space, we’re independent spirits,” she said. “We are very similar; we were born on the same day, 25 years apart.” She added, “We’re not afraid to be verbal, to express ourselves. I wear everything on my sleeve and so does he, which is good.”

The birthday exchange underscores a public, affectionate facet of a high-profile couple whose careers and family life regularly attract media attention. The reactions to Douglas’s nickname — including questions from fans who noted the wife-vs.-sister distinction — illustrate the quirks of social media commentary in celebrity culture. Yet the couple’s coordinated posts and the visible affection from their children also reflect a long-standing, publicly shared family narrative that remains central to their public image. As the family navigates a joint birthday and ongoing professional commitments, observers will likely continue to parse the subtleties of their social-media messages and the warmth that underpins their public persona.