Transcript for Twin Sisters Separated at Birth Reunite

This is the story of the morning. It's terrific. Two wonderful young women strangers living thousands of miles apart. Never knew one another, came across one another by absolute happenstance and found that they shared a life-changing secret. I'm going to JFK from L.A.X. So I can see my sister for the first final. Reporter: Imagine growing up adopted quite happy, perfectly content when at age 25 you get a Facebook message from a stranger 5,000 miles away on a different continent who looks just like you, exactly like you. On February 21st, 2013 I got a message on Facebook from a girl in London. It said she had seen me in a youtube video and then after looking my name up online saw we were both adopted. When I saw her profile it was crazy. She looked just like me. Reporter: Meet Samantha fudderman living in Los Angeles and Anais boardier, a French fashion designer in London. Last February Anais saw Samantha in this youtube video. You can't imagine you have a twin sister somewhere you don't know about. Reporter: Anais sent her that Facebook message, one that would change their lives forever. What was that first moment like? I put the phone down to put it away for a second and I was like, picked it back up and kept looking at it and checked everyone I knew. Reporter: They would soon discover they both have been adopted after being born on the same day in the same Korean city. Could it be? Were they identical twins separated at birth? My connection is really bad. Reporter: Decided to Skype with one another. Oh, my god. You're european. Hi. This is a weird experience. Yes, so weird. Reporter: What was the visceral reaction of seeing yourself talking to yourself? It was weird but I feel like there was a strange calm and comfort, as well and something that I can't really explain. Reporter: Life story shared in that first conversation. Everything. Yes. We talked for three hours. Reporter: Really. Yeah, like so much and then she's like, I have to pee. I got to go. I got to go too. Welcome to London's heathrow airport. Reporter: Their first meeting in London. First things you said. I touched her head. Reporter: Again in los Angeles, taking in the beach, some baseball, even the perfection that is in-n-out and reuniting once again here in new York. Oh. Reporter: So here's the deal. I'm going to ask you a question, okay? Just a couple little rapid-fires and I want you to answer the same time. Morning person or night person. Night person. Yes, night person. Coke or Pepsi. Coke. Coke. Now this will actually be individual. If I ask you for one pet peeve -- Shower curtain touches me I hate that. Oh, my god, it's the same. I hate that. Reporter: Then they would get their DNA tested just to erase any doubt. We got our DNA test results. I'm going out on a limb here. You're sisters, aren't you? Yeah. Yeah. Holy . Reporter: How has it changed you? I think it fees a lot more confidence knowing it's like, yeah, I found my second heart. Did you ever feel like there was a part of you out there that was missing? I did feel like I missed something. I had an imaginary friend -- it happens to a lot of kids, but I had an imagine Farry friend. She was called Ann. I needed that comfort, I guess. Reporter: They decided to make a documentary about their experience and say they've already heard from countless other adoptees thanking them. You seem a bit overwhelmed by the idea of that power to affect other people's lives. Why? It's an overwhelming thing to know that -- she's like tiny asian hobbits can make a difference. It's so silly but it's -- it brings back all that joy and happiness as a child. And it makes it real. What is it like to be able to touch each other. Just right, I guess. It feels Normal. It's just how it's supposed to be. Your necklaces, what does it say and the significance of them to you is what? It says best friends forever and I got them for Christmas because I never had them growing up. It sounds really crazy but I think we need those little kid moments and those cheesy mopes together. You feel like you get to go back and color in a picture you know how it will look but get to have the fun of coloring it in. That it's the exact feeling. It's not the longing or searching to figure out what it was, it's just constant support and like love filling up. And the joy of finding out. Yeah. We did bond over, you know, I'm adopted, as well and as adopted kids, you let yourself wonder for maybe a moment but to actually -- you mentioned "Parent trap." Two different accents is the first thing you think of. That struck Samantha, the Angelino, wow, that's me with a French accent. I mean you can't get over it. It's like you're constantly in that moment with you and, again, just remarkable, remarkable girls and by the way, again, we saw they are creating a film, a documentary about their jump think and to learn more about it go to goodmorningamerica.com on Yahoo! Great story. Thank you to both of them. Anais and Sam. The chances she would have seen that youtube video. I mean and then -- I said, do you guys -- you know, a special thank you to mark Zuckerberg. Thank you.

This transcript has been automatically generated and may not be 100% accurate.