A leading Beijing paternity testing center says up to 30 percent of tested men were not the biological fathers of their children.

The Forensic Science Center of Beijing Genomics Institute, which has 19 offices across China, said there had been a 20 percent annual increase of paternity tests since it was founded in 2002.

A clinic worker surnamed Wu said 30 percent of tested men at the clinic had not fathered their children, and that the real proportion could be higher.

"Actually, some couples coming here for the tests are not married in real life. The 'husband' that confirmed a biological father of the child is indeed the woman's lover."

Beijing Chaoyang Hospital's paternity test center also reported a sharp increase in paternity tests.

When it was founded in 2000, the clinic conducted a dozen tests. Last year, more than 600 paternity tests were carried out, said Xiao Bai, who is in charge of the center.

Wu said paternity tests were on the rise as more suspicious Beijing husbands are checking on their wives' fidelity.

He said the center conducted more than 3,000 paternity tests last year, 20 percent higher than last year.

"It always happens after the husband finds out their wives are having an extramarital affair," Wu said.

And it is not just husbands who are insisting on the test.

The number of women opting for prenatal paternity testing has also shot up in recent years. "They want to know whose baby they are carrying," Wu said.

"If the husband discovers he is not the biological father, it is divorce or abortion."

Over the past decade paternity testing technology has advanced and Beijing now has nearly 20 testing centers.

The test costs between 1,000 to 1,200 yuan (US$146 - 176) per person, and the results are ready within a week.

"There would be more people coming here if the cost of the tests become lower," said one unnamed worker from a Beijing biotech company.

The worker said typical clients are aged in their 30s, well-educated and with a good job.

"Usually, couples begin to drift apart as a result of different work locations or frequent business, then husbands begin to doubt their wives' fidelity," she said.

Sociology specialist Wang Xing attributed the increase of paternity tests to the loss of the loyalty within marriage.

"With the society more open and diverse, social attitudes and behavior towards sex and family seems to become relaxed and casual. Nowadays, casual sex or one-night stands are no novelty, marriage and family become vulnerable and people lose confidence in a loyal marriage," he said.

"In China, most families have only one child, if it turns out that the child is another man's baby, that may be a disaster for the family.

"Suspicious husbands check on their wives' fidelity through paternity tests also suggests that Chinese husbands require chastity and complete loyalty from their wives.

"But under the open-minded situation, the expectation of total loyalty from a wife might just be too high," Wang said.

(China Daily September 23, 2009)