In some countries, taboos are enforced by laws, such as the dress codes introduced in strict Muslim countries. Breaking these taboos can lead to severe penalties, from banishment to death. But, in many cases, they merely cause a sense of shame.

Taboos often reflect the history of a culture. For example, in some cultures, it is considered acceptable for a widow to marry her brother-in-law. This would make sense in a society where women are vulnerable, men are scarce due to wars or disease, and the population is sparse. But in modern or Western societies, it causes social discomfort and seems to reflect less consideration for women's rights.

In ancient China, women's feet were broken to make them appear smaller and more attractive. These days it would be unthinkable to consider inflicting such pain on a child. But, in those days, it was the norm, and girls who had not had their feet bound would stand less chance of marrying well.

As society becomes more free, certain taboos fall, yet others remain. One such example is the disease Aids. In countries where HIV/Aids is no longer a death sentence, people are not afraid of admitting they have the disease. Yet in places where medication is scarce, and health and educational services are not readily available, Aids victims can find themselves cut off socially or even threatened.

Taboos in Chinese society today

Homosexuality

Homosexuality has been legal in Hong Kong since 1991, when the Legislative Council agreed that homosexual relations among adults would no longer be a crime. But same-sex marriages or civil unions are not currently recognised here. In June 2009, the government recognised same-sex couples living together in its Domestic Violence Ordinance. Yet, there is currently no law against discrimination on the ground of sexual orientation.

In recent years, homosexual support groups have become more active in calling for equality. But many members of the gay, lesbian, bisexual and transgender communities are seldom accepted by their friends and families, especially in Chinese society where traditional values, and roles of male and females, are deeply rooted.

Women Coalition of HKSAR (WCHK), a non-profit organisation advocating the rights of the local lesbian community, conducted a survey last year. It found that out of the 510 women surveyed, 53 per cent felt discriminated against on a daily basis. A gay student said she had been punished by a teacher, who told the class not to talk to her.

Death and Suicide

Death is one of life's absolute certainties, but it is taboo in Chinese society. It is not discussed openly, especially during weddings or birthdays. So great is its power, the number four, which sounds like the word 'death' in Cantonese and Putonghua, is avoided. This is why many buildings in Hong Kong do not have fourth floors, 14th floors, 24th floors and so on. Similarly, people will never buy a clock as a present for a friend because zhong has a similar sound to the word for 'end'.

These may seem like harmless customs, but they can result in some important issues being avoided - like teenage suicide, an issue few people are equipped to deal with.

Social worker Heung Mo-yan says: 'We think young people should be enjoying life without too many worries and they will not think about taking their lives. When it does happen, most adults don't know how to take it.' Heung is the centre-in-charge of Suicide Crisis Intervention under the Samaritan Befrienders Hong Kong.

Last year, the centre received a total of 1,398 calls for help, with 1.9 per cent from teenagers up to 19 years old. Heung says there are three main reasons young people wish to kill themselves: relationship problems with their families, or with their partners, or study pressure.

Heung says parents play a crucial role in preventing suicide, but often they are unable to discuss the issue with their children. Not only is the subject taboo, they don't know how to deal with it.It is vital, she says, that parents maintain open dialogue with their children.

'A 16-year-old girl wrote a note about her plan to take her life after two weeks,' she says. 'The mother found it and came to seek our help. Instead of talking to the daughter, she told us she was going to take her daughter on holiday, hoping the 'plan' would be forgotten after the trip.

'We strongly advised against it and urged her to discuss the death note with her daughter openly.

'The truth is, if you don't face the problem by discussing it, it will become serious. In this case, the death note could be a cry for help from the daughter who thinks: 'if my mum doesn't talk with me even after she finds it, she doesn't care about me at all'.'

It's not the kind of problem that will go away if ignored. Modern teenagers have access to other sources of information and advice that may not be in their best interests.

The internet is a gateway to a world of information - and misinformation.

'They have access to all kinds of irresponsible, wrong messages about the topic. There's no control at all,' says Heung.

Last year, the centre set up a website with information and discussions on the myths about suicide. There are inspiring video clips and live chats with volunteers and social workers.