Sterling K. Brown gets emotional after discovering the truth about his ancestors

On This Is Us, star Sterling K. Brown plays a character who once struggled to discover where he came from. However, on PBS's Finding Your Roots Tuesday night, Brown actually received some huge revelations about his real-life ancestors and their ties to slavery.

Host Henry Louis Gates Jr. explained that a common dilemma African Americans face is that they are unable to trace their ancestors' history because their stories were obliterated first by slavery and then by Jim Crow. On top of that challenge, Brown, who also opened up about the day his father died when he was only 10 years old, shared that he doesn't know much about his father's side of the family because when he lost his father, he also lost the chance to learn more about his paternal roots.

That all changed when Brown was shown his grandmother's death certificate, which revealed that his father also lost his mother at a young age, and also traced her ancestry back almost a century to Brown's third great-grandparents, Henry Woodley and Sarah Nelson, who married in the year 1870.

"It's like the mystery of it all, like, that people actually existed," said Brown. "You know in theory that, like, you have to come from somewhere, but now you have real people with real names and real birthplaces. It's surreal in its realness, you know, to actually see it. And even if it doesn't go further back than that, the fact that, like, next time I go to Mississippi it's going to be, like, a different sort of thing for me."

The 1900 census was where Gates discovered Brown's third great-grandparents were living with Sarah's mother, Nancy, and that all three of them were born before the Civil War. "So you know what that means," Gates stated to Brown, who replied, "It just hit me, like, they were slaves."

Brown admitted that he had thought about his ancestors being enslaved, but he "never thought" he "would be able to trace it, to actually know it."

However, while his father's ancestry may have been a mystery prior to Finding Your Roots, Brown's mother's roots were even more surprising to the actor, when he learned where his fifth great-grandparents were born.

"Birthplace of father, Africa. Birthplace of mother, Africa," said an emotional Brown. The actor added, as a tear fell down his face, "Wow, man. Wow. That's cool."

Since transatlantic slave shipments became illegal in the United States in 1808, Brown's ancestors "likely arrived during the very last few years of the slave trade. Whereas most African Americans descend from people who arrived here earlier, too early to be recorded in the censuses following the Civil War," explained Gates.

"So you're a recent African," Gates told Brown. "Isn't that interesting? Because lots of other people would've, by 1820, would've been descended from generations of Americanized Africans. But you weren't."

"This is, like, I can say, you know, well, you know, my fifth great-grandfather and grandmother, they were from Africa or whatnot," said Brown. Gates confirmed, saying, "You can say, unlike 99 percent of our fellow African-Americans, you could say I know about when my ancestors came because they were my fifth great-grandparents." This made Brown incredibly happy as he thoughtfully repeated again, "That's cool."

Finding Your Roots airs Tuesdays at 8 p.m. on PBS.

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