Traditionally the Chinese family is a close-knit affair. Parents are expected to give a home to their children and their brides or grooms when the children marry. Later the parents, when they age, might expect to be given a home with their children. Traditionally family members show each other great respect and politeness.

But on June 20 in Shanghai something went wrong in the Chen family home. After a year living together the 25-year-old wife and her 60-year-old mother-in-law had a bitter argument which ended in them attacking each other with hammers. Both were taken to hospital with head injuries after being separated by neighbors and police. Was it just a case of in-law trouble? Some suggest mothers-in-law are problematic but Shanghai mothers-in-law are a special breed.

Mr Chen, the devoted son and husband, who was not at home when the fight broke out, is at a loss as to how to keep the peace in his home. Neighbors say the two women have been arguing with each other for the past year because of different attitudes, traditions and personalities. Mrs Chen hails from another province. Poor Mr Chen says he has run out of ideas. He has tried to make sure the women don't quarrel, but he cannot afford to buy another apartment to keep them apart and at peace.

As society changes and people move outside their hometowns and provinces, clashes between the younger and older generations and between people from different parts of China are becoming more common. Especially in Shanghai.

Shanghai women are famous for their style, elegance, aloofness and sharp tongues. But when they become mothers-in-law, are these what their sons and new daughters really need?

The outsiders

In 2009 the Shanghai authorities registered 39,734 marriages where a Shanghainese married someone who was not from the city. That constituted 32.7 percent of all the marriages for that year but by 2011, 40 percent of all the marriages here involved someone from outside the city. Three quarters of these were Shanghainese men marrying women from outside.

Statistics also show that most of these couples are among the poorest people in the city. An economic survey revealed that 41.6 percent of these couples enjoyed a monthly income below 900 yuan ($141) and that most of the outsider wives were not well-educated and did not work at good jobs. More than half of the non-Shanghainese wives lived with their Shanghainese parents-in-law or other family members because they could not afford their own apartments.

One neighborhood committee in Yangpu district told the Global Times that a third of the cases it dealt with involving domestic disputes were in families with non-Shanghainese wives.

A committee official surnamed Chen said: "We cannot state that the relationships between non-Shanghainese wives and their Shanghainese mothers-in-law is especially difficult, because no one thinks domestic disputes are caused just by people coming from different places, but I personally think that this leads to different lifestyles and attitudes, and is certainly a cause of many of the disputes in families with non-Shanghainese wives."

Always on the outer

Gan Niejuan is a 34-year-old office worker employed by a finance company. She married her husband, a Shanghai man surnamed Chao, six years ago and she now lives with an "authentic and typical" Shanghainese family, though she actually has a Shanghai hukou (residence permit). Gan came to Shanghai from Anhui Province and went to university here. Now even though she has lived here for years, has a hukou and is married to their son, her parents-in-law, Mr and Mrs Chao still think of her as a "waidiren" (a non-local).

The Shanghainese are renowned throughout China for their haughty attitude to anyone who was not born in Shanghai.

"I can feel this attitude in my parents-in-law from time to time, especially from my mother-in-law, though they try to hide it. For example, they sometimes reassure each other by saying, 'Well, she is not Shanghainese, you have to forgive her,'" said Gan. "This makes me feel as if I am a country girl who has never seen a city."

Gan said another problem was that when Mrs Gao was introducing her to relatives or friends, she would look down unconsciously and lower her voice when she explained that Gan was not from Shanghai. "This is another thing that makes me feel weird - is there anything wrong with not being from Shanghai?" Gan asked.

Mrs Chao, a 65-year-old retired high school teacher, admitted she could be difficult, but she is also open-minded and respects people.

"To be honest, if I could choose a daughter-in-law, a non-Shanghainese girl would not be my first choice because there really is a big gap, which I don't think can always be overcome, between the way Shanghainese and non-Shanghainese deal with work and life," Mrs Chao said. "But my son loves his wife and we respect and support his choice."

Mrs Chao admitted that she did feel uncomfortable when she had to explain to others that Gan came from another province. "People of my generation believe that only poor Shanghainese men marry non-Shanghainese women. And to tell the truth my daughter-in-law still has a long way to go to be a real Shanghainese daughter-in-law, especially as she is not from here and does not know the local customs."

Mrs Chao said she had once invited some friends home, but after saying hello to everyone, Gan slipped back into her bedroom and stayed there the entire day while Mrs Chao was busy preparing snacks and food for her guests. She was embarrassed by this because she felt Gan did not behave the way she should have.

"On occasions like this when older people are present, a daughter-in-law is expected to come out and help a mother-in-law prepare food and chat with the guests. That's what Shanghainese mothers would teach their daughters. You are now also the hostess of this family so you have to shoulder some responsibility, even if you are shy or not good at cooking, at least you can sit there and smile," Mrs Chao said.

"I just think she has not been aware that there are problems. Some of these problems occur because she is not from Shanghai, if you want to put it that way," Mrs Chao said. She added that she had told her son to discuss these things with his wife as she thinks he would be the best person to do this. But so far the son has not expressed any interest in being involved in these family matters.

There's nothing new about these disagreements. Wang Yuru, the chairwoman of the Shanghai Psychological Counseling Association, told the Global Times: "Conflicts between wives and mothers have been common throughout China's history, for these two women both want to win more love from the son and husband. Shanghai women have an elegant refined lifestyle and they want their daughters-in-law to match this as well. The girls who are not from Shanghai are at a disadvantage because they do not know the local customs, culture and social rules."

Nasty characters

In Shanghai's theater and literature, the nasty mother-in-law and the poor daughter-in-law are traditional characters. One old saying goes: "In time a daughter-in-law will be promoted to be a mother-in-law." Books and plays suggest daughters-in-law have to expect a great many hardships because of their position. In the Shanghai dialect a married son is nicknamed "plywood" - a term that paints a vivid verbal picture of someone under extreme pressure from both sides. But it is the sons who are the keys to preventing or managing disagreements between mothers and daughters-in-law.

It is not always the case that there are rows. Wang Tian is a 27-year-old Shanghai man who has been married for two years. He told the Global Times that though his wife is not from Shanghai, there have not been many major disagreements between her and his mother.

"I talk to each of them constantly to see if they have any concerns or problems, even for trivial matters like how they drink water or squeeze a toothpaste tube. I try to persuade them to accept the way the other does things," he said.

Wang said the things that could cause the biggest disputes for mothers and daughters-in-law were home decorating, weddings and babies. "Chinese parents usually want to take care of everything for you, even when you have grown up. They just want the best for you always, and you and your wife have to bear this in mind."

He believes communicating is vital to avoid misunderstandings in families, especially communicating with his wife. "It is not difficult to talk to your mother and get her to understand, but your wife is a comparatively new person in your life and you need to spend more time and make a bigger effort to win her understanding," Wang said.

When they were decorating their new apartment, Wang and his wife had planned to knock down a wall to make a cloakroom but Wang's mother insisted they keep the wall so that air could circulate better. Wang was caught between the two approaches but after thinking about it and talking to friends and colleagues he decided not to knock the wall down.

Then he talked with his wife: "Darling, mom is working hard decorating the apartment for us. Why don't we agree to her plan to cheer her up and make up for some of the work she has been doing? I know you want a room that you have designed, but I am planning to buy another apartment and I promise you will design the décor for that by yourself." His wife agreed.

A good opportunity

And Wang took the opportunity to make his mother promise not to get involved in their wedding plans, thus avoiding another potential conflict. "Sometimes I feel like a card dealer, exchanging wins between the two sides to keep them both happy."

Wang said it would be better for the two women not to live together. "We have tried to live together before, but it is too hard. Every mother thinks she is the woman best qualified to take care of her son. She therefore sets herself as the benchmark and then values the son's wife according to this. It is impossible to find a wife the same as your mother."

If, as there inevitably will be, there is a disagreement between a wife and a mother, Wang suggested that a husband should support whichever side is logical, not to water things down or always support one person. Otherwise the other woman will feel she is being treated unfairly and will become angry at this.

Psychologist Wang Yuru suggested another approach to avoiding family disputes. "Modern people are so anxious to achieve success in life and work that they cannot balance themselves sometimes and too easily become impatient and angry and quarrel with family members. If they can control their anxiety and stress, I think there will be fewer disagreements between mothers and daughters-in-law."