UPDATE: The secret has been reveal! Click here to find out who was reunited with Oprah!

On monday, Oprah Winfrey will reveal a family secret on The Oprah Winfrey Show.

The hit show has reunited many families in the past 25 years. On Monday, however, the family reunion/secret involves Oprah's own family.

I was given some news that literally shook me to my core, she said. Only a handful of people in my life know about this.

It's the miracle of miracles, she added.

To watch the official promotional video for the show, click here.

So what will her secret be?

The twittersphere and blogosphere buzzed over the weekend with speculations. Of the serious ones, the real identity of her father, a long-lost half sister, and a long-long child are some of the popular guesses.

Kitty Kelley -- who penned a revealing unauthorized biography of Oprah by interviewing her relatives -- claims the secret will be a half-sister who was given up for adoption when she was a baby, reported the Chicago Sun Times.

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