As a primary school child, Lina wondered why she did not look like her parents, who had darker skin than her.
The niggling doubt grew until one day four years ago when she found out she was adopted during a heated spat with her father.
After finding her real mother's name and last-known address hidden under corrective tape in a health booklet, she set out on a mission to find her biological family.
It proved fruitless until she turned to Facebook in August this year, and found her answer in just a month.
Lina, 26, did not want to use her real name as her adoptive parents are unaware that she has reconnected with her biological family.
She spoke to The Sunday Times at her birth family's flat in Toa Payoh, sitting comfortably beside her brother, Mr Nor Insaf, a 32-year-old debt collector.
It did not appear like they had spent their whole lives apart. He teased her incessantly and she retaliated by hitting him playfully with a sofa cushion.
Recounting her search, she said: "I saw some videos on YouTube and thought, 'If people in the US can do it, why not in Singapore? Singapore is so small.'"
At the end of August this year, the senior reservation executive created a poster with a photo of her face, contact details and information on her birth mother.
Armed with 20 printed copies, she went to her mother's last-known address in Yishun and distributed them to residents in the four-storey block.
Then she posted her plea on Facebook and urged her 500 friends to share her post.
In just three days, the number of shares climbed to 5,000. She was even approached by Streetdirectory.com which shared her poster on its Facebook page and tagged her mother's last-known address. It was the first time the mapping website helped such a cause.
On Sept 26, a day she will now never forget, she received a phone call from someone claiming to have information. Within an hour, she was walking to a Starbucks outlet at Bugis.
"I wasn't afraid, but I had so many emotions," she said. "I didn't want to get my hopes high."
When she arrived, a table of six waved her over. She did not know who was who, but when she was introduced to her brother, she broke down.
Lina met her mother that night at her flat. It was a reunion with tears and hugs as her family welcomed her into their lives with open arms. They chatted for two hours.
"When I was already there, my questions didn't matter anymore. I accepted whatever she said," she said.
Her brother would only say that his mother gave Lina away at birth because she wanted to make life better for his little sister.
"My search was going on for four years," Lina said. "For it to end in just three days was unimaginable."
It is healthy for adopted children to have questions or the desire to search for their birth parents, said Ms Teo Seok Bee, a senior manager at Touch Adoption Services.
She "strongly encouraged" adoptive parents to share with children their adoption story at an early age because transparency builds intimacy.
Lina now goes regularly to the Toa Payoh flat where her mother lives with her 17-year-old brother and 15-year-old sister. Her stepfather also lives there, and her older brother, whom she is closest to, visits their mother there every day.
Lina is trying to make up for lost time. Her brother, smiling fondly at her, said: "She wants me to compensate for 26 years of her life. We message each other every morning, afternoon and night."