Jack Nicholson grew up believing his grandmother was his mother and that his biological mother was his older sister. Born in 1937, Nicholson’s family chose to hide the truth to avoid scandal — his mother June was only 18 when she became pregnant, and the father was a married man. In the conservative 1930s, his grandmother Ethel raised him as her own, while June moved away to pursue a career as a showgirl.

For nearly 40 years, Nicholson lived unaware of the secret. He followed June to Los Angeles as a teenager, thinking she was simply his only sibling, and started building his career in Hollywood. But in 1974, while reporters researched a feature about him ahead of the release of Chinatown, they uncovered the truth about his family history, revealing that June was his biological mother and Ethel was actually his grandmother.

The discovery stunned Nicholson, who later described the revelation as “the most messed-up thing” he’d ever heard. By the time he learned the truth, both June and Ethel had already passed away, leaving him unable to confront either of them. His aunt Lorraine — whom he had believed was his other sister — eventually confirmed everything.

Despite the shock, Nicholson held no bitterness toward his family. He admired their commitment to protecting him and keeping the secret, even joking publicly about his “sister-mother” later in life. It remains one of Hollywood’s most surprising real-life twists — a revelation as dramatic as any role Nicholson ever played.