By Ha Mi
BBC Vietnamese service
Despite rapid development, Vietnam is a conservative society
Vinh, a 24-year-old man, says his parents never talked to him about sex.
"But they would make jokes about it so that I know what they expect from me," he says.
Vinh is from Hue, one of the most traditional cities in Vietnam, but this attitude is found throughout the country, according to the authors of the first survey into sex and sexual attitudes carried out in the communist state for 50 years.
By turning it into a joke, some parents and children find it is easier to talk about sex without being judged or getting embarrassed.
This attitude seems to apply to all - young and old - in Vietnam.
But for some, the subject really is no laughing matter. The communist state is deeply conservative and sex is a highly sensitive subject.
Economic liberalisation and development have made Vietnam a more open society and there has been a noticeable change in sexual behaviour.
Medical experts say increasing numbers of people are having sex below the age of consent, leading to rising numbers of unmarried women having abortions.
There is also the problem posed by unprotected sex and more people contracting HIV.
Faced with these dilemmas, there have been discussions about putting sex education on the school curriculum at an early age.
Based on the findings of the sex survey, some people think that may not be such a bad idea.
Researchers spoke to 245 people in both rural and urban areas over six years.
They discovered that teenagers or young adults "never" or "hardly ever" talked to their parents about sex.
The parents too admit that they do not speak to their children about it.
For those who do feel they should discuss the subject with their children, just how to broach it is difficult.
Diep Hoa, a mother of two, is typical in this regard. She says she used a letter to talk to her 17-year-old daughter about sex.
"I wrote to her and gave the letter to her on the day she left home to go to study abroad. I told her that I would like her to read it while on the plane," explains Mrs Hoa.
"I mentioned a lot of things in the letter, including sex and relationships. I would like her to understand what love is, what sexual relationships are and the consequences when one loses control of their sexual desires."
The survey also found that what is okay for a man is not okay for a woman.
Hong Hanh is a 22-year-old presenter of a live radio programme on HIV and Aids prevention targeted at young people.
"All male callers said that sex before marriage for men is normal and okay, but they would not want to get married to someone who has lost her virginity through sex," Hanh says.
According to Dr Khuat Thu Hong, one of the three authors of the research, "Vietnamese people have a very poor, misperceived and somehow one-sided view about sex, because there is no open or serious discussion of the matter."
She says this is very dangerous because "it leads to a lot of wrongly imposed sexual perceptions toward men and women, and it limits both sexes from enjoying a sexual relationship."
Some experts say that sex education, which is only taught in some schools, should be made compulsory because young people would benefit from the knowledge provided to them in a serious manner rather than through jokes.
However, there has been opposition to this suggestion from those who uphold what they call "traditional values".
The funny side
Teachers too find the subject highly embarrassing, and some parents and children see nothing wrong with discussing a highly taboo subject in a humorous way.
Back in his very traditional hometown, Vinh smiles and gives some examples of what his parents tell him.
Report author Dr Khuat Thu Hong says sex should be taken seriously
"They say: 'If you get her pregnant before marriage, you both won't be allowed to go in the house by the front door', or 'you won't be allowed to go near our ancestors' altar'.
"Another favourite is: 'We will have to make a small shed near the pigsty for you to live in!'"
This indirect and light-hearted way that some parents use to talk to their children about sex as a means of educating them is also a warning to children of the consequences of sex before marriage.
But faced with rising underage sex and HIV, Dr Hong says it is about time that Vietnamese learned to talk openly about the subject.
And she hopes that the findings of the first sex survey in half a century will help change social perceptions and understanding of what remains an extremely delicate matter.