please join in the conversation on facebook and twitter. thanks for watching. i'm john quinones. "20/20" starts right now. they told me i was abandoned at the hospital and i could not believe it. this story is -- this is crazy. >> tonight on an all new "20/20," a condition so rare and mysterious, it's almost unheard of. a bizarre medical disorder. denying that you are pregnant and abandoning your babies. >> how could your wife give birth and you have no idea? to miss her pregnancy five times? >> what caused a mother to abandon her newborn? >> there is a drop box. the box that you were found in. >> now we're on the hunt with both grown children. >> both sought out to find their birth mother. >> right. >> here tonight, a dna detective. >> you're back to where it all started. >> taking then on the search of

a lifetime. >> that's really all we have to go by, is your dna is the location that you were found. >> all the brand-new leads and blind alleys. >> i don't want to give you any false hope. this is a long shot. >> the setbacks and rejections. >> she hung up on me. >> i always thought maybe somebody was thinking about me and where i was. >> if surprise of something they never saw coming. >> and i saw this. i had the same reaction. >> and the biggest shock of all, who is waiting behind that door? >> it really is opening pan pandora's box. >> and a big secret. >> i'm david muir. >> i'm amy robach and this is "20/20." reporting tonight, deborah roberts. >> who am i? where am i from? >> i was left at a hospital. >> i was left out in a donation bin. >> i just wanted to know why.

>> there's this feeling of not being wanted. >> reporter: coeur d'alene, idaho, a small scenic town just outside spokane, on a lake, nestled in the mountains. its name, originating from a native american tribe who called themselves "the discovered people." but while some are discovered here, others are lost. our first mystery begins in 1987 at this hospital. a pregnant woman checks herself in alone in labor and oddly, carrying no luggage or personal items. >> she said she was from california, and that she was visiting some friends in idaho. she was 5'5", brown hair, brown eyes. they said she was attractive, but quite uptight. >> reporter: she signs in as

amy dee beach claiming she is single and unemployed. at 6:30 a.m., she's moved to the birthing room. >> she gave birth to a healthy baby girl, good size, full-term. >> reporter: after a short time with her new baby, the mom does something inexplicable. >> she disappeared 12 hours later. she just left the hospital gown on the bed and that was it. >> reporter: she just walked out. >> she was just gone. >> reporter: mystified, the nurses give the now-abandoned baby girl a nickname. >> they named the baby, um, baby girl beach which is pretty cute, actually. one of the better names for a foundling that i've heard. >> reporter: foundlings? >> foundlings, sort of the catch-all term for a child that's abandoned. >> reporter: this foundling is later adopted by a couple from idaho. >> this was, you know, such a dream that we had had for so long. when they brought her out, here came this beautiful, beautiful little girl. this little baby.

>> santa brought this for me? >> reporter: the klugs are a loving family, naming their new little girl andrea, an only child enjoying piano, swimming, gymnastics. flash forward 31 years, baby girl beach is now andrea klug-napier, who lives in colorado and works as an office manager in a medical office. she had no idea of the strange circumstances around her birth until age 16 when her adoptive parents finally told her. >> they told me that i was abandoned at the hospital. and i could not believe it. but this story is -- this is crazy. >> reporter: a crazy mystery she feels compelled to solve. you have a tattoo. >> i do. >> reporter: what does it say? >> it says, "baby girl beach." >> reporter: "baby girl beach." because that -- that was sort of your identity in the beginning. >> right. >> reporter: you're living a pretty happy life. you've got lovely parents. why do you need to go looking if you're pretty happy with where you are? >> there's always going to be a void that you don't know about. i just have always wanted to

meet whoever she was. >> reporter: that "she," the mother who walked out on her hours after her birth was now the center of andrea's quest. she turns to social media to find her. >> my name is andrea. i was born on april 30, 1987. >> reporter: posting a photo of herself on facebook holding a sign outlining her story. >> i was abandoned at a hospital in coeur d'alene, idaho, um, by a woman named amy beach. please like and share. >> reporter: the post goes viral. >> it made headlines. >> using social media to try to be reconnected with her birth mother. >> reporter: many adopted kids say they have this sense of yearning. how different is it for those who are foundlings? >> it's even more intense. because foundlings have zero information about their background. it's like their life began the moment they were found. >> reporter: 2,400 miles away in

anchorage, alaska, another foundling mystery one year before andrea. another runaway mother abandons her baby. it's a cool summer evening in 1986. at sundown, a newborn baby boy is found not in a hospital, but in a cardboard box next to a salvation army bin. >> it was september 4, 1986, two teenage boys were out riding their bikes. they heard crying from a box and were astonished to find a live baby in the box. these two teenage boys, scoop the baby up and i guess literally cycled home to their house with it in their arms. >> reporter: hours before, bystanders recall seeing a pregnant woman nearby. >> they'd seen a very pregnant young lady standing by the salvation army bin. hadn't given it much thought, but when they'd gotten home, they started watching the news, and heard that a baby had been abandoned there. >> reporter: like andrea, this

>> reporter: a police sketch is published in the local newspaper. looking for the woman who abandoned the baby. and like andrea, this baby boy doe is also adopted into a loving home. he grows up in idaho, the state where andrea was born, playing in the hills, "doing country stuff," being raised along side two sisters. flash forward 31 years later, that baby is now benjamin tveidt. a soldier in the idaho army national guard and has deployed twice to iraq. >> how did you learn that you were adopted? >> it was my 11th birthday, my dad, he told me i was adopted. >> how did it hit you? >> i didn't believe him at first. i was devastated. they brought the newspaper clippings out that they had preserved. i was spinning. i mean i was like, "what, this is, this is all a joke, right?" this was the biggest question in my life, um, who, who am i, where am i from? i would look up at the stars

some night and wonder if my mom or dad or if my brothers or sisters or my grandparents were looking at the stars that night. >> reporter: ben is now on his biggest and most personal mission to date, trying to solve the mystery of his birth. like andrea, he's put his faith in one woman, cece moore, a world-renowned dna detective whose dna crime-solving work recently dprgrabbed nationwide attention using dna to lead to arrests in a number of languishing cold cases. >> i've worked with dozens, maybe hundreds of foundlings by now. and so i know that this is a, a really intense process for them. this is a major game changer for these cold cases. >> reporter: still ahead -- andrea's about to find out some secrets get buried for a reason. >> you may have this idea that you are going to find birth

parents who are just going to readily accept you, but that may not be the case. >> reporter: and a stunning discovery for ben. >> and i saw this. >> reporter: stay with us. ... what is your online banking password? [audience gasping] oh, dear... [clacking metal] it was 'windbreaker,' now...it's... [muttering] ...spelled...like cat names... [baby crying] [gasping] [dramatic music] [whistle blowing] [dramatic music subsiding] [triumphant music & cheering] your digestive system has billions of bacteria but life can throw them off balance. re-align yourself with align probiotic. and try new align gummies with prebiotics and probiotics to help support digestive health. who says summer gets all the fun? not us. because southwest has $69

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>> reporter: on a trip back in time, back to 1987, a year of coincidences when this u2 song about searching topped the charts. ♪ and an abandoned baby is the story line in the number one movie "three men and a baby," >> i'm not picking it up.

>> put it back where you found it. >> reporter: where roommates discover an abandoned infant left on their doorstep. it was also the year that andrea was abandoned in real life at this hospital in coeur d'alene, idaho. now she and genealogist cece moore are retracing the steps of the mom who left her, hoping to find clues that might unlock the mystery. >> you're back to where it all started. >> so a lot's changed since 1987. >> this is one of our post-partum rooms which actually is similar to what it was back in 1987. >> i wonder how much time she spent with you. >> at least she was good enough to come in and have you in a hospital. >> the feelings that she could have had, i can't even imagine. >> not that she's a hero, but it took a lot of courage to come in. >> it was a criminal offense to leave a baby somewhere. now fortunately safe haven laws have been created where women

can take a baby to a safe place like a fire department, hospital and they won't be prosecuted. >> reporter: a barren hospital room offering no answers for andrea. then suddenly, an unexpected emissary from her past. this nurse, the same nurse who 31 years ago cared for andrea as an abandoned infant, kim beckman remembers trying to fill the void left by the baby's vanished mom. >> i remember holding you a lot. i worked evenings -- and rocking you and wanting you to feel loved. >> i did thank you. >> i just remember how cute you were and how desperate that mom must have been. i hope you find your birth mom. >> reporter: sadly, clues are hard to come by in the maternity ward. with the exception of one. andrea's mother left behind an admission form. and on it? next to andrea's baby footprints -- her mother's

fingerprint. >> was that significant for you? >> well, it was certainly a clue and it was the only clue we had. and, so, we did want to follow up on that. >> reporter: hopes pinned on this single fingerprint. andrea and cece enlist the nearby police department for help. >> i'm scott hogg. i'm the chief here in post falls. >> nice to meet you. >> very nice to meet you too. so, let's see what you got here as far as the fingerprints go. the name that was used was last name of beach? >> uh-huh. >> are you comfortable that she would have just walked away on her own that there was no foul play any of that type of activity that may have occurred? >> i don't know if there is any foul play. i don't know. >> i don't want to give you any false hope because this is a long shot, and i'll get in touch with you as soon as i hear something back. >> i feel like this is a puzzle that we're trying to put together. but all the pieces are face down on the table. >> reporter: like andr ben tveigt, also abandoned at birth, is determined to find his biological mom.

>> so right now we're heading to cece moore's house. >> hello. >> hi. >> come on in. >> i'm ben. >> it's very nice to meet you. >> likewise. >> reporter: cece has taken ben's dna and entered it into four national databases, hoping for a match to his biological mother. with possible hits on distant relatives, the dna detective's got her work cut out for her. but then, she catches a break -- a direct hit on someone they weren't even looking for. >> i logged into your match list a couple of days ago, and i saw this. r.b. is your father. >> reporter: ben does an actual double take. >> i had the same reaction. >> how did the planets align perfectly for that to happen? >> it's a man named richard blanshfield, who's a pretty incredible guy. he's a vietnam vet and he's not just any vietnam vet, he's a highly decorated vietnam vet.

>> reporter: what are the odds? ben, a veteran of two tours in iraq, is now learning his biological father is a war hero. >> his arm was nearly blown off at the shoulder. he was 47 years old at the time of your birth. >> is he still alive? >> he is still alive. here's the good news, your dad lives 20 minutes from here. he just happens to live down the freeway. >> did you believe this? >> i thought i got struck by lightning when she told me. to find a relative that close, it blew my mind. >> reporter: up next -- ben's visit, face to face with a father he never knew. >> i'm trying to regulate my breathing, trying to be calm. i knock on the door and there's this voice -- >> someone knocking on my door? >> reporter: and cece hits pay-dirt with andrea. >> and when i opened it, i had quite a surprise. >> i thought "wow, this actually worked." i just couldn't even get on a plane fast enough to go meet her.

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>> reporter: as a sergeant in the idaho national guard, ben tveigt has tested his mettle and grit

u.s.-led invasion in iraq. he's an experienced gunner on one of the most powerful tanks on the planet. >> we're driving to my dad's house. >> reporter: but now, ben has to muster all the courage he has for a deeply personal mission. >> i am terrified and excited all at the same time. the longest 800 feet of my life. >> reporter: genealogist cece moore joins him at a house in southern california where ben's birth father lives. >> you ready? >> i'm ready. >> give me a hug. i know your father is very excited to meet you. >> i'm trying to regulate my breathing, trying to be calm and not look like an idiot. i knock on the door and there is this voice. >> somebody knocking at my door? >> hello. >> hello, you must be ben. >> i'm ben. >> i'm doc. wow. how you doing? >> this is eerie. >> you bet it's eerie. come on in, son.

come on in. welcome. welcome. >> and i was just overwhelmed. i didn't even know what to say. >> did you feel a connection? >> yeah, right away. right away. >> reporter: his biological dad richard or doc -- blanchfield recipient of the purple heart, shares keepsakes from a rich life lived. >> see the pictures on the wall? >> mm-hmm. >> vietnam vet, 82nd airborne. >> reporter: the two are startled by the similarities in their lives. >> you went in the army, you were 18? >> i was 18 years old. >> so same as i did. i went to the marine corps at 18. >> reporter: what if anything does he remember about ben's birth mom? doc recalls a night 32 years ago in anchorage, alaska, as a single dad had a chance encounter at a bar called the cabin tavern. >> there was a young lady sitting at the bar. i sent up and sat down. hello, and had my beer and we started a conversation.

she was in a difficult relationship. i took a liking to her, she didn't want to go back wherever she came from. i don't remember the lady's name, honest to god i don't. >> reporter: he recalls making dinner for the woman. and the two sharing a tender, romantic night. >> before she left, i remember this distinctly, i had three statues, i still have two of them, they're from china and it was a chinese goddess statue and i gave it to her and i said, "this will bring you good luck." i never heard from her again. i wonder if she still has it. >> and here's sean my other boy. >> these are my brothers? >> yep. >> reporter: then a revelation of relief, doc says he would've kept his son if he'd known he existed. >> there was that feeling of rejection that i had for so many years being abandoned, and it, counter-balanced that feeling 'cause i wa -- i was accepted and i was wanted it lifted a weight off my shoulders, off my chest.

i couldn't go to bed angry anymore. >> reporter: as a parting gift, doc offers his newly found son a note. it says "we are family" and the marine coda "semper fi" always loyal. meanwhile, andrea's identity search has hit a snag. she was hopeful after offering that fingerprint from her birth mom to police. >> and did they find anything? >> fortunately no. i mean it would have been great to get the identity, but had her fingerprints been in the system, that probably wouldn't have been a very positive indicator. >> usually it's associated with crime. >> if they've been arrested, we didn't want to believe that she went on to live a life of crime either. >> place three swabs. >> reporter: but where old fashion forensics have failed, some high-tech dna sleuthing by geneticist cece moore has come up with a startling match, with with someone also in the dna database. >> this is your match list. and when i opened it, i had quite a surprise. >> if you share both parents, you would have big blocks of green. so how much green do you see? >> there's a lot of green.

>> there's a lotta green. do you know what that means? >> that we could be siblings? >> you're not just siblings, you are full siblings. >> whoa, that is so crazy. >> you share the same mom, and the same dad. >> suddenly you realize you've got a sister. for somebody who's not even really expecting much and you're seeing this now. >> i thought wow, this actually worked. i found something. i just couldn't even get on a plane fast enough to go meet her. >> reporter: wasting no time, andrea leaves colorado for wisconsin. >> i'm nervous to meet a stranger that just happens to be my sister. i was so nervous for her to open the door. i just didn't know what to expect. hi. >> hello. >> how are you? >> good. how are you? >> reporter: at first, andrea and her sister heather are reeling from a combination of awkwardness and a deep bond. >> i just knew immediately that we were both really shy and kind of awkward and she just immediately told me that she had

a bunch of information about our biological family. >> that's my adoptive mom. >> reporter: heather was adopted in washington, a state that allows access to adoption records. so, she already knows the names of their birth mom and dad. >> our birth mom's name is deirdre she went by cindy. this is our mom. >> oh my god. wow. >> reporter: after years of searching the moment has come, andrea is about to learn about her origins, but the truth will be difficult. >> she had a baby boy two years after you. >> oh my god. >> and the baby and her passed away. >> oh my god that is so sad. i am really glad to find all this out --

when i heard that news i just. it took over. i just couldn't even. i just came to a stop. i -- i will never be able to meet her. >> and to hear this from your sister who you just met. >> yeah, it was sad. all this time i thought maybe somebody was thinking about me and where -- where i was. but she hadn't. it feels like i just lost somebody and -- that i didn't even know. >> reporter: and there's an astonishing twist in her family saga. while andrea and heather were given up, their mother and father kept and raised two sons. >> we knew that the boys were raised by our mother and father. >> why were they raised by your biological parents and you weren't? >> yeah. so, we had a lot of questions. this dimple, yeah. totally. >> reporter: next -- andrea starting her journey alone, now paired with her sister, together they will travel to meet their two

brothers and their father. >> oh, boy. >> reporter: and confront a deep family secret. a mysterious notation on their mom's death certificate. >> it was no normal death certificate, not what you would expect. >> reporter: stay with us. is this at&t innovations? yeah, wow..this must be for one of our new unlimited wireless plans. it comes with a ton of entertainment options. great, can you sign for this? yeah. hey, uh.. what's in that one? that's a shark. new and only with at&t, you can get unlimited data, 30+ channels of live tv, and your choice of things like hbo or pandora premium. more for your thing. that's our thing. visit att dot com. your mornings were made for better things than psoriatic arthritis. as you and your rheumatologist consider treatments, ask if xeljanz xr is right for you. xeljanz xr is a once-daily pill

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>> reporter: andrea klug-napier has discovered a sister, and together they are going to meet two brothers they never even knew they had. >> super nervous, i kind of have

a stomachache. >> reporter: and someone else, their biological dad. >> oh, boy. >> reporter: with their mother gone, they hope their father holds the key to their looming question. why would a mom and dad forsake their two daughters, but not their sons? >> hi. how's it going? >> good. >> hi. >> i'm aaron. >> i'm andrea. >> hi. nice to meet you. >> nice to meet you. >> nice to meet you. >> reporter: older brother aaron answers the door and then the sisters come face to face with their father dwight. >> have some flowers. >> thank you. >> reporter: the family finding their footing as dennis, another brother joins them. >> so you were meeting your biological father and your two brothers that you never had any idea existed? >> i can't even describe the feeling. it was crazy. the article they had in the newspaper, the nurses described her as uptight and attractive.

that's what it says. dwight just immediately started talking to us and telling us everything that he knew about our mother. we just wanted to see every picture that was ever taken of her. >> in this picture of her, minds me so much of heather. >> you guys look like mom big time. >> yeah, yeah. >> reporter: dierdre, who went by the name of cindy, was only 16. and dwight, just 17, when they married. she later worked as a computer programmer. >> then he told you about the day she died. >> yeah. >> it was 20 below here, weather was bad. the city was shut down. and she told me she had the flu. >> she told us that she had been ill. and that he left for work and that when he got home she was unconscious. >> i called 911. >> reporter: and what happened? >> well, they come and took her to the hospital and went to the hospital and they pronounced her dead.

all the doctor said was that she was really torn up inside. it wasn't till i went home and it was couple of days later -- i went to the bedroom doors were locked. you know, i went in there and there was a -- there was a baby sitting on the bed. full-term baby. >> reporter: a unimaginable discovery. the death of a baby boy he hadn't known he fathered. >> i thought i knew her, i thought everything was great. >> reporter: but what about andrea and heather? incredibly, dwight says he had no idea his wife gave birth to them either. >> and that's the story. >> yeah. >> it was pretty brutal. >> i thought at first i'm for sure gonna see something in dwight that maybe he did know and he's hiding it from us. but, immediately when we sat down, he started talking. i knew that there was absolutely

no way that he knew about us. >> she hid everything from him. you know, all those pregnancies he had no idea about. >> most people would look at this and say how could this be? how could your wife give birth and you have no idea? >> i still question it myself today, wondering how did i miss it? >> reporter: he says when cindy was pregnant with their sons aaron and dennis, she barely showed. >> her stomach wasn't big at all. it was just seemed like she gained a little weight around the face. >> reporter: you are living together in the same house, you're -- sleeping together in the same bed. you must have seen her disrobe. >> i thought it was weight gape or something. >> reporter: you never recall her looking pregnant? >> no, not ever. >> reporter: how is it possible that his wife could give birth and he knew nothing about it? >> i've worked with families, people always question how could no one know? how could you hide a nine-month pregnant belly? but women do it all the time. >> reporter: the sisters still

reeling from it all visit their mom's grave to say goodbye. still confounded by why she hid those pregnancies. the answer may lie in a strange notation on cindy's death certificate. "unattended birth associated with psychotic denial." >> reporter: had you heard of that before? >> i have seen it in other cases. that's not terribly unusual in foundling cases, where somebody denies they're pregnant until it's too late and they haven't made any sort of arrangements. it's probably one of the reason that some people get abandoned rather than legally adopted. >> denial of pregnancy is a, is a recognized psychiatric or psychological condition. >> reporter: psychiatrist susan hatters-friedman has studied the disorder and says it's surprisingly common. 1 in 400 women may suffer from some form. >> the woman may have no idea that she's pregnant or she may have some idea that she's pregnant intellectually but she pushes it from her mind. until she can no longer do so, um, because she's suddenly

giving birth. and certainly a young woman's own experiences of abandonment, could contribute to denial of pregnancy. >> reporter: possibly explaining cindy's odd behavior is a simple back story as a child. as a small child, cindy and her sister were both given up for adoption. they were on a bus, en route to an orphanage. >> and at the last minute, their brother pulled her sister off the bus and left her. >> reporter: left cindy. >> cindy. alone. >> reporter: by herself. >> she's just a little girl, almost 3 years old, on this bus alone, who's sent off to some orphanage. >> reporter: must have been traumatic for this child. >> it's abandonment again. we only can speculate what sort of emotional damage that may have done to cindy very early on in her life. >> reporter: still ahead, andrea d heaer about tr moth eveore secrets to her grave. and ben's search for his mother has been narrowed down to two

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plus, ask about flexible channel packs. click, call or visit a store today. >> reporter: anchorage, alaska, known as "the last frontier." and for ben tveight, it is the final step in finding the missing link to his past. desperate to connect the stot . >> hi. >> dave cook. >> nice to meet up. >> reporter: believe it or not, he locates the detective who was one of the first on the scene three decades earlier. >> you didn't have any physical trauma, anything like that.

the umbilical cord was tied up with a sandwich tie. >> reporter: the most promising lead, that police sketch of a possible suspect, never got an i.d. >> there were several possible prints, but they were poor and not very useful. >> if fingerprints were lifted, would they have been preserved? >> we're talking 30 years now. >> right. >> and basically all the photos have been destroyed, the prints have been destroyed. >> reporter: and yet again, old-school crime-solving is futle, leaving it for cutting edge dna technology to save the day. but genealogist cece moore's got her work cut out for her. so far, she's been able to identify two of ben's second cousins. one on his mother's side, the other on his father's side. she traces their family trees, all the way to their great grandparents. she then builds the family trees forward with their decedents. poring over obituaries, gravesite locators, and census records, she painstakingly begins a process of elimination.

she had it down to two sisters. one who would be ben's aunt, and the other, would be his mother. >> how certain did you feel that you had the right two women that probably would wind up being his mother? >> oh, i -- i felt completely certain that i had the right two women. because of the way the family trees came together, there was just no other explanation. >> reporter: for ben, it's the meteoric moment. >> i'm going to see if she's willing to talk to me. i've been less nervous doing operations in baghdad than i am right now. >> reporter: unannounced, he's rolling the dice, pulling into the office building where one of the sisters works, certain she's either his aunt or his biological mother. >> tell me what your feeling is. you're dialing that number and you're waiting. >> the keys on the phone felt pretty heavy as i was pushing 'em. here we go. >> hi. [ bleep ] my name is ben. i have been put in touch with you by some people of a mutual acquaintance.

i'm looking for some long lost family members. >> so, she answers. >> i hear the voice. a middle-aged woman's voice, and it was a little standoffish as first, trying to figure out who i was. >> reporter: the startled woman on the other end of the line immediately denies that she or her sister could possibly be ben's mother. >> the only reason i'm so adamant about it is that the dna brings us to a path that leads here. i'm not trying to be accusatorial. there's no malice or negativity on my end. i just -- i'm holding onto just a thread of hope. right now, that's all i have. >> reporter: it's devastatingly apparent that the woman, either his mother or his aunt, wants nothing to do with ben. >> i'm sorry for inconveniencing you this afternoon. bye.

she's extremely adamant that her and her sister are a dead end, but people can lie. dna doesn't. i just don't know. crawling back inside of myself, starting to feel nothing again. this is okay. that will pass. >> reporter: minutes later though, a heart-stopping, paralyzing moment. ben's cell phone rings. is it a ray of hope? could the woman have had a change of heart? >> hello? >> reporter: instead, it's a final blow. the woman's sister calling back, to tell ben to never contact them again. >> just out of curiosity -- she hung up on me. she said that i need to go back to where i'm from, and love my

family, and love the people that raised me. >> so, there was no warmth or no acceptance at all on this phone call? >> no. the meat and potatoes of the conversation were, i was messed up for coming and interfering with other people's lives and digging things up that shouldn't be dug up. >> did that lead you to believe that she probably was your biological mom, or maybe not? the fact that she was so defensive. >> her reaction led me to the conclusion that she's probably the mother. >> do you feel rejected? >> yeah. it shouldn't have to go -- have that feeling twice. rejection, abandonment, not being wanted. a special kind of loneliness. well, i felt that loneliness again in the car. that wound is probably still open. >> for the adoptee, they want answers. but for the mothers, this is probably one of the most difficult things that they've ever had to deal with.

>> when they get contact from their child, it really is opening pandora's box. they have to face a lot of deeply buried emotions. they've carried a -- a lot of shame, a lot of guilt, and fear. >> and a big secret. >> a big secret, and it could disrupt the lives that they've built since. >> reporter: ben reaches out to his adoptive father back in idaho. >> i told him if -- if i had to go and do it over again, i wouldn't change anything in my life. i don't want to be a different person. everything that i am is because of you guys. >> i don't know if we created or just helped you along. you are a great person. you have a bigger family now. >> yeah. because the world has given me so much, and i was blind to that for 30 years now. it has never been clear until now that i have never been

alone. >> all right, son. i love you. >> i love you too. >> reporter: next, for andrea, the dark story of her mother's past is only beginning to unfold. you begin to suspect there are other children. >> i did. >> we knew there were five children already, but there was a 13-year gap between heather and andrea. >> reporter: could there be more siblings born during that gap? >>

thanks for the ride-along, captain! i've never been in one of these before, even though geico has been- ohhh. ooh ohh here we go, here we go. you got cut off there, what were you saying?

oooo. oh no no. maybe that geico has been proudly serving the military for over 75 years? is that what you wanted to say? mhmmm. i have to say, you seemed a lot chattier on tv. geico. proudly serving the military for over 75 years. you ok back there, buddy? stop fearing your alarm clock... with new*! zzzquil pure zzzs. a drug-free blend of botanicals with melatonin ...that supports your natural sleep cycle... ...so you can seize the morning. new! zzzquil pure zzzs. super emma just about sleeps in her cape. i'm super emma. but when we realized she was battling sensitive skin,

we switched to tide pods free & gentle. it's gentle on her skin and takes care of stains better than the other free and clear detergent. so she can focus on saving the world, with a little help from dad. dermatologist recommended. it's got to be tide. >> reporter: andrea klug-napier's journey to find her biological family has taken emotional twists and turns she never could have imagined. her family tree keeps rapidly growing. >> i grew up an only child, and now i have so many siblings. >> reporter: she has three n newfound siblings, heather, aaron and dennis, and now incredibly, she's about to meet a fourth, a 32-year-old sister. >> i had heather just out of the blue sent me a message on facebook and said, "are you sitting down?" and then i found out i have another sister. >> reporter: andrea has traveled

to washington state and once again, she is knocking on a stranger's door. >> hi. >> hi. >> oh, my gosh. >> it's so nice to meet you. >> we actually look a lot alike. >> can you believe all of this? >> no. >> i never thought i would find anything out ever. >> reporter: her sister's name is marysia, and just like andrea, her course of life may very well have been changed by her mother's strange medical mystery. birth mother cindy arrives at this hospital in spokane under an alias, gives birth and then hours later, vanishes. >> the name was fake. >> did you ever search that name? >> it is such a common name. >> same with amy beach. >> yeah. exactly. she said she is from california. >> reporter: the two sisters marvel at their mirroring stories and reflections. >> like, looking at her was so surreal to see these features that i see in myself everyday. >> i think andrea and i did have a connection when we first saw each other.

we're both hesitant and a little bit shy, and i think that actually, you know, helps us kind of understand each other a little bit more. >> reporter: and believe it or not, another stunning find. a fifth sibling. a 35-year-old brother that cindy gave birth to and abandoned at another hospital. another child that dwight never knew he fathered. >> it's one thing that you missed it one time. >> yeah. >> maybe two times. >> but to miss her pregnancy five times? >> yeah. right. >> reporter: that's really pretty stunning. >> uh, i just couldn't, didn't know she was pregnant. couldn't tell -- >> do you see them as your children? >> oh yeah. they're my kids. >> reporter: andrea's search has led to an unforeseen family reunion, and for her adoptive mom, beverly, a chance to thank the man who brought her daughter into the world. >> thank you. >> you did a great job of raising her. >> it takes nature and nurture,

together, we've produced a very beautiful young woman. we are part of her story. it's just a miracle that we have all found each over. >> reporter: as for ben veidt, though the search for his birth mom ended with a harsh rejection. he rejoices in the discovery the special man who gave him life, a second father who embraces him fully. >> reporter: are you happy you set out on this journey? >> oh yeah. yeah. i could go to my grave happy knowing all that i know now, some foundlings don't ever get that closure. i really, i really feel that connection to another human being in this world. i'm thinking law school after. >> now we're talking. there is a future for you, ben. >> i value myself that much more after meeting him. >> reporter: in the case of andrea and ben, both sought out to find their birth mothers.

>> right. >> reporter: both found birth fathers. >> yes, with open arms, yeah. >> i always hope that there can be at least one connection to the biological family. somebody that welcomes them to the family, it gives such peace. i've seen such closure and peace of mind come to these people that are searching when they get that. >> peace and closure, but there is definitely more to come on this, amy. >> andrea has yet to meet that fifth sibling that lives overseas. that's it for us tonight. >> i'm david muir. from all of us here at "20/20" and abc news, thanks for watching. have a good evening and great week.

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