Last week, Oprah Winfrey revealed that a revealing revelation would be revealed...Monday!

She told viewers a family secret "shook her to her core" when she first learned of it months ago. She also teased brief footage of a reunion, with someone seen (only from behind) stepping from the shadows onto the stage for an embrace.

But who is it? Someone Oprah never expected to see again? Someone Oprah never knew existed? A child? A sibling? A doppelganger twin sister?!? Oprah called the news a "miracle."

Last year, the TV star did her best to ignore the release of Kitty Kelley's unauthorized biography, which contained allegations unearthed during interviews with relatives. One cousin said Oprah's biological father wasn't Vernon Winfrey, and claimed to know who was -- Kelley left the name unpublished, but did she privately share the info so Oprah could investigate the claim?

The big 'Oprah Winfrey Show' episode airs within hours, but all weekend, fans have been obsessed with The Oprah Family Secret, especially on Twitter ("I say it's that she was secretly placed here on earth by space aliens," said one tweet; "Oh, Sweet Baby Jesus, please don't let it be like in 'The Crying Game.' Please!" wrote TV reporter Bobby Rivers; "She's probably preggies," said one Twitter guesser). Read on for more intriguing, and absurd, possibilities!