Maryland neighbors and best friends discover they're actually sisters through DNA test

Two Maryland neighbors and best friends never understood why they felt so close to one another, closer than they did to their own families. Turns out, they were sisters.

Ana Zellers made the discovery through a DNA test where it was revealed that she and her childhood neighbor and best friend Joanne Smart shared the same father.

"I put all the pieces together," Zellers says, recounting the moment she broke the news to Smart. "I said, 'You realize that my son is the only living grandson of our biological father. And my son is your nephew...and my grandchildren are related to you."

The discovery is detailed on a new podcast from CNN called "Suddenly Family," hosted by journalist Samuel Burke.

"Eleven percent of people who take a DNA test will discover that one of their parents isn't their biological parent," Burke told FOX 5.

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He says the podcast episode about the Maryland women, titled "Girl Next Door," is one of the most moving of the series.

"She feels more at home with [the Smarts] than she does her own family," Burke says. "Well, it turned out that her mother had an affair with the neighbor's husband."

Other episodes of the podcast include stories about a gay man who finds out he has a child and even a personal anecdote from Burke himself about how he found out he wasn't related to his very own family.

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To listen to the "Suddenly Family" podcast, click here.