Since China initiated the opening-up and reform policy in the late 1970s, the country has changed beyond recognition, economically, socially and sexually. While millions of people have been lifted out of poverty as the country has grown to become the world's second-largest economy, the rise in living standards has also resulted in greater sexual freedom and a more tolerant society.
This has been great news for people such as Deng Yajun. Her working day involves dealing with one of the great secrets of the human body: the genes and the unique coding mechanism that distinguishes us from one another, but also provides links between families. Deng conducts DNA tests.
In the past 10 years, her team at the Zhongzheng Forensic Authentication Institute in Beijing has tested more than 50,000 DNA samples, more than 40,000 of them for paternity tests. The technology, which has been in use in China since the 1990s, has seen a rise in popularity during the past decade, partly because rising standards of living mean more people can afford to use it and also because the number of extramarital affairs has risen in China's rapidly developing society.
Suspicious husbands intent on finding out if their wife has been unfaithful have provided strands of hair, fingernail fragments and even discarded baby teeth. Sometimes, anonymous requests are sent to the labs via express messenger services.
"Anonymous requests account for 60 per cent of all DNA paternity tests," said Deng, 42, whose institute has seen the demand for tests rise by 15 to 20 per cent since 2000.
The introduction of high-tech equipment means conducting a paternity test has become far easier and is now more accurate than ever, according to Deng. A simple test costs from 2,400 to 3,600 yuan (S$490 to S$750) and the results are available within two weeks.
The number of tests has increased more rapidly in prosperous zones, such as South China's Guangdong Province, including the cities of Guangzhou and the manufacturing hub of Shenzhen. Local news reports indicate that the People's Hospital in Shenzhen, which neighbours Hong Kong, has seen an annual 50 per cent rise in the number of paternity tests since 2000.
The sexual revolution hasn't been the only driver of advanced DNA testing, though. In the past five years, the popularity of paternity testing has been boosted by the government's moves to strengthen the management of birth certificates. For the first time, the sixth national census, conducted in 2010, explicitly stated that children born outside the country's family planning policy, which limits most couples to one child, are eligible for hukou, a household registration certificate, but only if the parents can provide the results of a paternity test.
People in the cities are taking paternity tests because they've had a child in contravention of the family planning policy or outside marriage. However, for migrant workers whose children were delivered at home and therefore don't have a hospital birth certificate, the test is the only way of proving a blood relationship between parents and child. Without such proof, it's virtually impossible to obtain a permit that will allow the child to live in a prosperous area.
Figures from the institute show a huge rise in the number of parents taking paternity tests to obtain hukou for their children since 2009. "Nearly 70 per cent of all DNA paternity testing is undertaken to obtain a certificate of parent-child ties," Deng said. "But unfortunately, around 1 or 2 per cent of those tests have produced unexpected, or unwanted, results - that is, the child isn't the offspring of their nominal father."
According to Sun Liyang, director of the Xinjiang Forensic Authentication Institute, more than 80 per cent of all paternity tests conducted by the institute are the results of private requests. Around 50 per cent of the 300 tests conducted by the institute last year were motivated either by a desire to obtain hukou or because of suspicions about marital loyalty. Among those 300 tests, nearly 50 per cent disproved the child-parent link. The number of requests has risen by 50 per cent annually during the past three years.
While the proportion of requests from suspicious husbands has fallen, compared with the soaring number of tests conducted to determine paternity or to obtain hukou, pregnant women have gradually begun to account for a larger share of the business.
"They are looking for the baby's natural father," Deng said, adding that she recently dealt with an expectant mother who arrived at the test centre accompanied by four men, because she didn't know which was the baby's father. Deng said cases such as this account for 5 to 10 per cent of the total. Most female clients are married and have been pregnant for more than 16 weeks. "The number usually peaks during summer," she added.
The rise in the popularity of paternity testing is regarded by some as the inevitable byproduct of a more open society.
"It's understandable that people are losing confidence in loyalty in marriage because we've seen or heard about more one-night stands and cheating within marriage," an Internet user named "Little Apple" commented on her micro blog in relation to a news report about a man in the southwestern municipality of Chongqing who conducted a traditional paternity test on his son by mixing their blood in a bowl of water.
Chen said people's greater awareness of the law and self-protection, plus wider social tolerance of extramarital relationships set the stage for this rising trend. "But the crisis of trust within marriage is not due to the test, which only provides scientific proof," he said. Some experts attribute the growth of DNA paternity testing to traditional ideas that demand chastity and total loyalty from women. Given the restrictions imposed by the family planning policy, an illegitimate child might prove financially disastrous for the parents.
"The rising number of people taking DNA paternity tests indicates that the status of women and their rights in China are still confined to bearing children," said Yang Dawen, a professor of marital law at Renmin University of China who is also deputy director of the China Research Center for Marriage and the Family.
"Personally speaking, I think parents should try to love the kid, even if it's been proved that there are no blood ties, because the child already has an emotional connection with the family," he said. "But if the husband or the wife can't accept the result, or in some cases, refuses the test, their decision should also be respected."
Yang pointed out that the child might be emotionally damaged by the testing process. "We should think more about the potential harm to the child," he said.
DNA technology doesn't just prove blood links with parents, but can also give a reliable judgment on other genetic relationships, such those between brothers, sisters and cousins. However, in "genetic relationships" tests, the lower the number of comparable samples provided, the greater the cost. For example, if a woman and a man to want know whether they are brother and sister but they don't have samples from their parents, the test will cost more than 10,000 yuan.
This booming market has naturally attracted some illegal operators. In December, a man in Zhejiang province sued an illegal DNA testing centre because it gave him the wrong result, which denied the blood link between him and his son. After taking a test at an authorised centre, it was proved that original result had been inaccurate.
Generally speaking, paternity testing falls into two categories - those for civil purposes and those for criminal investigations. Testing centers are commonly authorised by local judicial departments, or are registered with the local commerce department and supervised by the health department.
During the testing process, the DNA in the samples is magnified several million times to make it big enough to reveal hereditary information. By comparing samples, the result can be determined, based on certain hereditary principles.
As a committee member of the Beijing Forensic Medicine Association, Deng has visited other testing centers to help them improve their accuracy rates. She said very few centers still use imported kits that only have 15 loci (the specific location of a gene or DNA sequence on a chromosome). "Because of the large population in China, 15 loci are not enough to recognise some of the distinctions," Deng said.
Since 2010, some Chinese companies have developed testing kits with 20 to 40 loci, which have greatly improved the accuracy rate. Many of the illegal institutes, however, still use 15-loci kits.
Interpreting the result is also of critical importance. Deng said it's inevitable that some abnormal data will emerge, which provides a challenge to the readers looking to prove or disprove a blood relationship. Sometimes, the abnormal data is the result of the concentration rate of the samples. "To make the correct decision and provide a responsible result depends on experience. That's why we urge people not to turn to the illegal institutes just because they are cheaper," she said.
Some customers will even undertake several tests if the results aren't to their liking. "Actually, if the result turns to be a non-blood tie, we will usually retest the sample twice or even three times because we realise that such a result will be difficult for most families to handle," Deng said. "But still, there's no other answer; there's only one true result in a DNA test."