(CNN) Paula Madison grew up knowing she was different.

Born in the predominantly African-American neighborhood of Harlem, New York, she was raised by a single mother who looked Chinese.

"When my mother opened the door and told me that dinner is ready, other kids would be very surprised," Paula says. "Sometimes, they'd start using racial slurs."

Madison's father was African-Jamaican and left her mother when she was three.

"My mother always looked sad because she was away from her family," she says. "I've known for my whole life that my grandfather is Chinese. I thought helping my mother find her family would make her happy."

Paula knew that her grandfather had gone to Jamaica from China in 1905 to work on a sugar plantation and after his contract was fulfilled, he stayed in Jamaica to open a store.

She was determined to find out which village he came from and if he had any living relatives in China, but the only clue she had was her grandfather's name: Samuel Lowe.

Paula Madison's mother, Nell Vera Lowe.

'Hole in my heart'

Madison said she traveled to Jamaica "maybe 20 times" without much progress. Her luck changed when she went to Toronto in 2012 for a conference on the Hakka, an Chinese ethnic group that emigrated widely, and met scholar Keith Lowe.

"I said, 'Oh my god, you're the only Chinese Jamaican I've met with the same last name as my grandfather'," Madison recalls.

Madison begged Lowe to investigate, and Lowe promised Paula that he would contact one of his nephews in Hong Kong, despite having never heard of a Samuel Lowe.

The next day, Lowe emailed Madison telling her his nephew had another uncle living in the southern Chinese town of Shenzhen; the son of Samuel Lowe and his Chinese wife.

Madison said the discovery of her mother's half-brother took her breath away.

A month after the discovery, she traveled to China to meet her uncle and her extended family although her mother, who died in 2006, never had a chance to meet them.

She learned that her tiny family in Harlem has 400 living members in China and she had a family tree going back 3,000 years.

"It felt like a hole in my heart and my soul has finally been filled," she says.

Large numbers of Hakka migrated to the Caribbean in search of work in the 19th and early 20th century, and inter-marriage rates were high. By 1920, at least 4,000 Chinese immigrants lived in Jamaica, Madison found through the course of her research.

Paula says the discovery that she had a huge extended family in China, compared to her small family in the United States, brought her much happiness.

Which box?

Since she found out about her family in Shenzhen, Madison has been back to China 13 times. This year alone, she's traveled to China four times.

Because she wanted other people in her position to have the same experience, on her most recent trip in November of this year she invited two more African-Americans with Chinese heritage along -- including her cousin, John Eckel.

Eckel's grandfather was from the same village in Shenzhen as Madison's grandfather and also traveled to Jamaica, where he wed Eckel's grandmother in an arranged marriage.

"I'm very close to my extended family in Jamaica," he says.

Eckel's mother was born in Jamaica and went on to pursue a degree at Boston College when she was 16. After she graduated, she moved to New York City, where she met her husband, who is Trinidadian.

Until this trip, Eckel had never been to China before. He had no idea what to expect.

"When I need to fill out my ethnicity form, I sometimes tick the 'other' box and write down multicultural," he laughs.

"Sometimes I'd check Caucasian, African-American and Asian at the same time."

Chelsea Hayes says she felt much safer in China than she did on trips to visit extended family in Jamaica.

'What are you?'

Chelsea Hayes was born and raised in San Jose, California.

Hayes' great-grandfather immigrated to Jamaica from Kowloon, Hong Kong, and her grandfather and father were both born in Kingston, Jamaica.

"Growing up with my African-American mother, I always identified myself as a black woman," says the 26-year-old.

But she says her almond-shaped eyes and Asian facial features always had people asking: "What are you?"

"I'd tell them I'm part black, part Chinese, and they would ask me, 'Which side of you is Chinese and which side of you is black?'" Hayes says.

John (L), Paula and Chelsea (R) at the Hakka Folk Culture Museum in Shenzhen.

'Surreal and eye-opening'

The three Americans traveled to Hong Kong, Shenzhen and Shanghai on their trip. In Shenzhen, in south China, Madison's Chinese family took the new arrivals on a tour of the Hakka Folk Culture Museum.

The expansive museum explores the customs, culture and traditions of the Hakka people. All three Americans can trace their roots back to southern China, where the majority of the Hakka people were from.

"I learned that most of the Hakka women are shopkeepers. My whole life, I have loved to grocery shop and peruse goods, now I know why!" says Chelsea.

Both Chelsea and John say the trip has overturned many of their expectations about their ancestral homeland.

"Coming to China has been surreal and eye-opening," says Eckel, adding he's been amazed at the size and sophistication of places like Shenzhen and Shanghai. "Media portrays China as a poor country, I expected poverty."

He also expected Chinese people to be less friendly -- large numbers of Africans live in China , particularly in southern Guangdong province, and many have complained of facing discrimination and prejudice from locals due in part to a widespread stigma against dark skin.

"Everybody has been kind to me," he says. "Some people have just come up to me speaking Chinese. I wonder if they wonder what I am?"

Chelsea Hayes with Paula Madison's aunt, Anita Maria Lowe.

'A lot to learn'

Madison's aunt, Anita Maria Lowe, gave Chelsea a bracelet for health and fortune -- something Hayes hopes will bring her good luck in finding out more about her Chinese relatives.

"One of the most beautiful parts is that this trip solidified my desire to find my own family," the Californian says. "I think that Americans have a lot to learn about other cultures. I think we're missing the mark on a lot of things."

She says a few of her preconceptions were misplaced. "The narrative of China that I've heard in the past was that it was packed, dirty, loud," she says. "I mean, yes, I've had people touching me while I was on a train, but it's just like in Chicago."

She says she felt very comfortable and safe in China. "(When I'm there) I'm very happy. I don't feel like a foreigner. I'm feeling very at home."

Both Eckel and Hayes say they can't wait to go back to China, but it's not all been plain sailing for the Americans. Hayes says she still needs a little bit of convincing over Chinese cuisine.

"I keep thinking to myself, why is everything so wet and slimy?"

Hayes, a picky eater who doesn't eat beef, pork or duck, staples of Chinese cuisine, says, "I've been eating a lot of granola bars."

This article was updated on December 27, 2016 to correctly identify the heritage of Paula Madison's father, and to correct a quote at Madison's request.