“Finding Your Roots” host Henry Louis Gates Jr. swapped out his hosting chair for the first time to become the guest during the Season 11 finale.

Hosting in his place, genetic genealogist CeCe Moore helped Henry Louis Gates Jr. uncover a long-held family secret. “I feel naked over here,” he said while sitting across from Moore.

Gates, at the start of the episode, recalled a formative moment in his life: Looking at a photo of his great-great grandmother, Jane Gates, the oldest known family member in his ancestry. From the age of 9 on, he was obsessed with family histories.

“The woman who sparked this fascination also harbored my family’s biggest secret,” he said.

Growing up, he was told Jane Gates had five children and they all had the same father. But who?

The Gates family had a theory the father of Jane Gates’ children was a man named Samuel Brady — which Moore proved wrong in the episode. Though Gates and his relatives did have one element correct: The father of at least one of Jane’s children was a wealthy white landowner.

Moore uncovered genetic evidence that Jane Gates’ youngest child was fathered by Charles Wesley Kelley, a farmer. Kelley was killed at 35 years old by lightning while closing a window, according to a local paper.

“I pictured my long-lost ancestor quite differently,” Gates confessed. “Death by lightning. Are you sure this is my ancestor?”

Gates continued to laugh and marvel.

“I’m thinking this guy is going to be descended from one of the signers of the Declaration of Independence or something,” Gates laughed. “Even as we’re talking, I’m embracing Charles W. Kelley. And, I’m sorry he was killed by laughing, it’s just not what I expected.”

Moore believed Kelley did not father all of Jane Gates’ children and possibly never met Edward Gates, moving to Illinois before his son was born.

Moore also found more details about Gates’ ancestry that he said shocked him even more. She was able to zoom back into Kelley’s family tree to find Gates’ third great-grandmother, a woman named Hannah Kelley (maiden name Stotler).

Through the Stotler name, Moore learned more about Jane Gates’ life in slavery. She was listed as a “piece of property” in an estate record of Christian Stotler, Hannah Kelley’s brother.

“This is so stunning. I am just floored,” Gates said. Wiping away tears, he said, “This is the most amazing discovery that I could have.”

“I just can’t believe it. After all this looking. This is just going to floor everybody,” he continued.

It appeared Jane Gates met Charles Kelley through his uncle, Christian Stotler. Stotler freed Jane Gates after three years, but indicated that her sons should be sold, though not out of state.

“Boy, that’s cold. He was freeing the mother but keeping her sons in bondage,” Gates said. “That’s cold and cruel. I would have been devastated.”

When Stotler died, Jane Gates and her two sons were sold to none other than Samuel Dunlap Brady, whom the Gates family initially believed to be the father of Jane Gates’ children. Her sons remained in slavery while she was eventually freed.

“They were close, they just didn’t get it right,” said Gates. “This is astonishing.”

Gates, in an interview with TODAY.com, reflected on the experience of telling his family.

“It was amazing. People cried and cheered,” he said.

Gates described the effect this lingering question had on his family.

“I have a great family tree but the box next to Jane Gates was empty. All we knew was that he was white. If something like this is in the atmosphere of your family, you become obsessed with it,” he continued.

“Every time there was a family gathering, people would argue. They always picked the richest or smartest white people in Cumberland, Maryland as the candidate,” he continued.

Gates was able to tell his family about Charles Kelley in person. “When we finally put the last piece in, like a jigsaw puzzle, the whole place erupted and went crazy,” he said.