Erika Olzheim-Smit and her adopted daughter Callista at Huainan Railway Station in Anhui province before they left for the Netherlands in 2004. Provided to China Daily

Erika Olzheim-Smit and Andrea de Baar-Smit are twin sisters from the Netherlands. They have much in common, including both having adopted Chinese children.

This has brought them to China several times in recent years, including their most recent trip in May, in an attempt to find the biological parents of their adopted children.

Olzheim-Smit, 50, and a mother of four, has an adopted daughter named Callista, who is believed to have been born on Dec 26, 2002.

The baby was found by a local man in Huainan, Anhui province, at the local railway station the following day, the man said, and taken to a welfare home by the local police.

In April 2004, Olzheim-Smit adopted the girl and took her to the Netherlands.

"She is a happy girl who is talkative and has many hobbies, including dancing and singing," Olzheim-Smit told China Daily. "She is very kindhearted as she always likes to help people whenever they need her."

When Callista was in first grade, she became curious about her biological parents. To satisfy her daughter's curiosity, Olzheim-Smit brought Callista to China in 2008, hoping to find clues as to who her biological parents are. Although no evidence was found, Callista gained a better knowledge of the country she came from.

"We don't think Callista was lost unexpectedly but believe she was abandoned. We told her about the one-child policy. She would also like to know if she looks like her biological parents, brothers or sisters," Olzheim-Smit said.

Similar reasons drive Olzheim-Smit's twin sister, de Baar-Smit, who has five children, the youngest two of whom are boys adopted in China.

Stefan, now 12, was adopted in Harbin, Heilongjiang province, in 2004, and Vincent, 10, was adopted two years later in Yixing, Jiangsu province. De Baar-Smit has previously brought Stefan to China to look for his biological parents. The entire family also visited China in 2012.

Olzheim-Smit said Stefan believes he was abandoned as a baby and resents his biological parents, although he doesn't know who or where they are.

Olzheim-Smit and de Baar-Smit returned to Huainan two weeks ago. However, the women appeared to be having a little more luck in their search this time.

With the help of Lyu Shunfang, a 63-year-old retired woman in Yixing who established a website to help people find lost family members, Olzheim-Smit and de Baar-Smit were featured on some local news portals.

After an article was published on June 4, a man claiming to be the girl's biological father phoned Lyu, but he withdrew his claim shortly after for unknown reasons.

A woman surnamed Kong also claimed she was probably Callista's mother. She said she gave birth to a girl in September 2001, but asked a relative to take her to the welfare home in Huainan. She did not want to raise the child because she wanted a boy, and China's family-planning policy was very strict then.

The relative claimed the girl was left accidentally at the railway station.

But the different birthdays raised questions about the woman's story. Kong said the welfare home may have made a mistake in their record-keeping, but the welfare home has denied this.

De Baar-Smit has not received any feedback concerning her two adopted sons.

On the advice of Lyu, the mothers went to a genomics institute in Beijing on Thursday to learn how to send biological samples from their children for DNA testing. They departed China for their home country on Friday.

"There will be much emotion in finding the children's biological parents. There will be good things and bad things, and we are all prepared to face either," Olzheim-Smit said.

zhulixin@chinadaily.com.cn