Growing up in Michigan, Korean-born Kara Bos always knew she was adopted. But when she finally located her assumed half-sister, the woman closed the door in her face and called police.
Now a court will rule tomorrow in a landmark case on Ms Bos's demand to be officially registered as her father's child.
It could set a precedent offering nearly 250,000 adoptees a chance to demand legal recognition as members of their biological families - and uncover a host of long-hidden family secrets.
Ms Bos, now 38, was two when she was found alone at a Goesan market, south of Seoul, and ten months later she was adopted by an American couple.
She rarely thought about her birth family growing up, but when her daughter turned two, it hit her "deeply what it really meant to abandon a child at this age".
"I thought about the excruciating pain my mother must have gone through to have to do this, and I wondered about the circumstances she could have been in to have to choose this painful path," Ms Bos said.
Efforts to trace her parents through adoption records proved fruitless, so she submitted a DNA sample to an online genealogy platform in 2016 and found she was related to a young Korean man studying abroad.
They established a relationship and worked out their common ancestor had to be his grandfather - the only person who could tell her who her mother was.
But his family wanted nothing to with her, rejecting her request to meet her father.
"It didn't matter the countless emails I sent begging and promising secrecy and never to contact them again if I could just find out my truth," she said.
"Even when I begged on my knees out of desperation in front of his oldest daughter's door for a face to face they would not allow me, and instead called the police on me," she told AFP, calling her plight "excruciatingly painful".
She filed a paternity suit, a move that revealed the man's address.
When she appeared at his door asking in basic Korean if he knew her face, he "looked straight at me but then waved me off".
Nonetheless a court-ordered DNA test showed there was a 99.987% probability he was her father.
"I just started wailing," Ms Bos said. "The truth had just set me free."
Ms Bos is seeking to be included in the man's family registry, an official Korean document detailing all household members.
If Friday's court rules goes in her favour she will be the first South Korean adoptee so recognised, giving her a legal entitlement to an inheritance and making her eligible to apply for South Korean citizenship.
Around 250,000 South Korean children have been adopted since the 1950s, according to Seoul's welfare ministry data, most of them overseas - the country was once among the biggest sources for international adoption.
After the Korean War it was a way to remove children, born to local mothers and American GI fathers, from a country that emphasised ethnic homogeneity.
More recently, it has been unmarried pregnant women who still face stigma in a patriarchal society - and are often forced to give up their babies.
Hosu Kim, a sociology professor at the City University of New York who researches South Korean birth mothers, said up to 15% of adoptions "point to extra-marital affairs", with the resulting children never acknowledged.
The South's existing laws prioritise birth parents' privacy over adoptees' rights, and the issue is shrouded in secrecy - many adoption files contain falsified information, or simply none.
Ms Bos was only able to pursue her case because of the online DNA match.
But Ms Kim said it could serve as a "critical precedent" that opened a way for adoptees to "claim their biological connections" and force fathers - and their existing families - to face the truth.
Ms Bos believes she is the product of an extra-marital affair, "one last attempt with someone else to have a son and as I was a daughter he abandoned me".
"I just don't know," she added.
In many countries, the children of sperm and egg donors have the right to know who their biological parents are, she said, but South Korean adoptees did not.
"I think it's something that's fundamentally a part of us all, the need to know where we come from."