The first time Sheng Jie heard of her older brother was at his graveyard. It was Tomb Sweeping Day, 2010.

"We went to honor my grandpa," Sheng said. "I was 16 that year, in my second year of high school. In the past, when my parents went to sweep my grandpa's tomb every year, they never allowed me to go. That year was the first time my father took me to the graveyard."

At the cemetery, Sheng saw a photo of her older brother on a tombstone. Her father then asked her to sit down by the tombstone, where he proceeded to slowly tell her about the boy's story.

Sheng was born in 1994. Her older brother had drowned at the age of 6 in 1992.

"When I was very little, there were blurry talks about me and my brother," Sheng said. "They said that I do not resemble my mother much. But my older brother did. That moment at the tombstone, seeing my father's back and my brother's photo on the gravestone smiling, I suddenly felt like a grown-up, mature enough to shoulder my parent's past and feelings."

Sheng's family is one of more than a million shidu (which means losing the only child) families in China. They belong to a unique group in which the parents were forced to have only one child because of the country's family planning policy but lost the child later in life. If there are more than a million shidu families, at least 2 million adults have suffered the loss of their only child.

And the number is increasing. Statistics from the Ministry of Health in 2010 showed that each year there are 76,000 new shidu families in China.

According to Jiangxi Provincial Commission of Population and Family Planning, there are currently 11,000 shidu families in Jiangxi province. Most of them were at the frontline of the country's family planning policy in the 1980s. Unlike Sheng's parents, most of these parents did not have a second child, mostly because the mothers were incapable of bearing a second child.

"This even led to divorce for some parents," said Jiang Xiaoling, a 20-year-old student from Jiangxi Normal University who has been volunteering to help shidu families in the province for the past two years. She is also Sheng's classmate.

"The father wants to have a second child, but the mother's physical condition won't allow her to have a second child."

Jiang first contacted many of the families through an online chat room that has brought together shidu families in Jiangxi province.

"For the first month, I did not dare say anything," she said. "I was very much intimidated because anything I say or ask could hurt their feelings."

It took Jiang a year to meet her first shidu parent face to face, Yang Weiguo.

Yang and his wife, in their late 40s, lost their daughter and only child in March 2011 in a car accident when the girl was in her 20s.

The couple sued the driver of the car in court, and on their request for compensation, they demanded 1 yuan (16 cents) for their so-called "single child compensation". It was the first time that such a demand was requested in a Chinese court.

Jiang met the couple in March, more than a year after their child's death. Jiang asked to visit the couple at their home for their first meeting, but Yang politely denied the request. The 50-year-old biked for about an hour to Jiang's university to meet her.

"Trust is a common problem for the parents," Jiang says. "Life in the past was a sweet circle for the family. Child and parents placed full trust in each other."

Traditional Chinese holidays that represent joy and reunion for families, such as Spring Festival and the Mid-Autumn Day Festival, are usually memorial days for shidu parents.

On the website www.tiantang6.com, an online mourning hall, shidu families buy virtual gifts for their dead children. Some parents who have known other shidu parents for many years even buy gifts for each others' children.

"This is the way they spend the traditional Chinese holiday," Jiang said.

The two years of voluntary work helped Jiang to understand about the "single child" from the parents' perspective. But for Sheng, listening to shidu parents time and time again has changed her attitude toward her parents.

"What these parents recall the most during our talks is what they used to do to take care of their only child. How to make delicious breakfasts for them, how to prepare them for school," Sheng said.

"My heart pounded upon hearing this. I suddenly realized that all of these sweet little acts of care, what these parents keep recalling, is what my parents are doing to me. For the first time, I feel so grateful for the family I have at the moment."

After a year of volunteer work for a shidu family, Sheng underwent a dramatic change. She no longer travels during the holidays. Instead, she spends her time off at home with her parents.

"I spent all the holidays traveling around China during my freshman year," she said. "I do love traveling. One of my roommates spends all of her holidays at home. I could not understand that at all. I saw no point in spending leisure time at home. But now, sometimes I even visit my family during the weekends.

She said her parents are happy to see her on the weekends and she knows that she mustn't let them feel pain a second time.

"They've felt pain once. It's vital that we love and care for each other, as a nuclear family," she said.