And the mystery continues.
Twenty months after welcoming her son Xander, January Jones is still keeping tight-lipped on the identity of the baby's father.
"That's my son's business," she told the New York Times in a new interview. "It's not the public's business."
When the very guarded Mad Men starlet announced her pregnancy in 2011, rumors ran rampid that the father could be anyone from X-Men co-star Michael Fassbender and Jason Sudekeis to Bobby Flay and director Matthew Vaughn, both of whom are married.
Believe it or not, a legendary actor may have influenced January's decision to keep the news to herself.
"Jack Nicholson once told me: ‘You should never give your personal life away, otherwise people will pick you apart. They’ll never believe in your character,'" she also shared.
But that doesn't mean she'll never reveal what has turned into being one of the biggest kept secrets in Hollywood — we'll just have to wait for it.
"Women should have lots of secrets. It’s our right to have secrets," the blonde starlet, 35, explains. "Otherwise, what would we write in our memoirs?
What do you think of January's choice?