But families are changing shape in China, as cultural norms confront new challenges.

These days, a household may consist of one person, several generations under the same roof, or a double-income-no-kids (DINK) family.

A national survey by Horizon Research Group released over the weekend shows that families in China's cities are becoming more and more diverse.

The most common family type in Chinese cities was once the nuclear family. But while it accounted for 48 percent of families in urban areas in 1997, that figure has shrunk to 37 percent today, the survey shows.

Covering more than 1,000 households in Beijing, Shanghai, Guangzhou and Wuhan, the survey found that the number of DINKs, one-person and linear or generational families are on the rise from six years ago.

The research group carried out a similar survey of family types in 1997, covering more than 5,100 households in 10 major cities across China.

This time round, more than 7.2 per cent of respondents classified themselves as DINKs, 1 percentage point higher than six years ago.

One-person households account for 6.8 per cent of respondents, 3.9 percentage points higher than the previous survey.

Linear families -- a married couple living with their parents or three generations living together -- surged in number by 6.4 percentage points, reaching 49 per cent.

According to social science experts, it seems certain more distinct lifestyles will emerge, for example, cohabitation and celibacy are both on the rise.

In any event, today's pluralistic society, with its diverse values, should be welcomed, said Li Yinhe, a sociologist on family and marriage. Everyone's choice, whether traditional or unconventional, should be respected, Li said.

Since the DINK lifestyle emerged in the 1980s, it has sprung up in all of China's big cities. Beijing now has 10,000 DINK families. When combined with those in Shanghai and Guangzhou, the figures rise to about 600,000, according to Youth League Committee of Beijing statistics.

Childbearing was in ancient China a family's top priority, but now it is regarded as a personal choice by many young couples.

Zheng Jian, a 38-year-old businessman, and his wife Xiao Yan, a graphic designer, think their two-person family is one of the happiest in the world.

They have been married for more than 10 years and have no children.

"We always have so many plans to do things together," Zheng said. "It seems like we are two kids who like playing together."

They insist: "We are satisfied with our present lives, so why bother with children?"

However, doctors warn that if they change their mind, they may have missed their most fertile childbearing years.

The best age for women to give birth is around 24 to 30 and, for men, it is 26 to 35. Exposure to a polluted environment also leads older couples to produce less active eggs and semen, increasing the risk of giving birth to babies with genetic defects, they said.

(China Daily July 16, 2003)