NFL legend and 2006 "Dancing with the Stars" champ Emmitt Smith uncovers his previously unknown family roots, and the trip takes him from Alabama to Virginia and beyond -- and even uncovers a family connection to the United States' former practice of slavery -- on tonight's episode of NBC's "Who Do You Think You Are?"

"I thought it would be a great way to connect back to my family heritage and take a journey that I thought would be very, very exciting and eye awakening for myself," he says.

Prior to the investigation of his family tree that he took for this show, Emmitt was only able to trace his roots back as far as his grandparents. Now, he has gone back much further and discovered that he was related to a slave woman named Mariah, whose sale was recorded in the Mecklenburg County Deed Book 22.

"When I go back and I find my great-great-great-great-grandmother Mariah in Deed Book 22, and the coincidence of me wearing [the number] 22 for about 16 or 18 years of my football career, when you connect that together, it was meant to be," he says.

It was Emmitt's journey to Burnt Corn, AL that taught him the most. He says, "Burnt Corn really told me a lot about both sides; the slavery side as well as the slave-master side."

Emmitt was also intrigued by a family rumor that his paternal grandmother, Erma Lee Watson, had white ancestry. What he ended up believing from what he learned was that a man named Samuel Perier, who was the owner of Emmitt's slave ancestors, may actually have been Mariah's father.

"I wasn't completely overwhelmed by the fact that I had a white ancestor," he says. "But the thing that really bothered me the most was just the way that my white ancestors treated my people and how they looked upon my family members. They looked upon them as cattle. Matter of fact, they looked upon them as less than horses. I'm just thankful that my heart has not been fueled with that type of conviction, or that type of evil. At the end of the day, that was then, this is now."

One of the most important things that has come out of Emmitt's journey has been the opportunity to sit down with his kids and have a conversation about parents, grandparents, and the evolution of a family.

"Kids will become parents and then their kids will end up being parents," he says. "And so they need to understand how all of that stuff works, and how they should understand who their relatives are and try to stay in contact with them."

"Who Do You Think You Are?" airs tonight at 8 p.m. on NBC.

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