Just over 2,000 Australian teenagers between 16 and 18 years old were asked about their sexual habits. While more than 90 per cent said they used social media, only 43 per cent said they had sent a sexually explicit text and 54 per cent had received one.

But when refining the search to look only at teens who were already sexually active, the stats jumped: more than 70 per cent had sent a sexual text and 84 per cent admitted receiving one - and more than half of these included naked or semi-naked images.

That's all very interesting but how do the Australian findings relate to Hong Kong and how widespread is sexting among teenagers here?

Stephanie, a Year 11 student in Hong Kong, says the practice is common among her friends as teen relationships are depending more and more on social media.

"Teenagers here are growing up in a busy city and I think they want to explore sexuality younger; it's inevitable here. That and there is so much peer pressure to be sexual, to be out there, to be fun; but teens are nervous too," she says.

"The thing with social media and sexting is there are no barriers, they aren't face to face so they feel more secure and do send texts and images, it makes them feel cool. Often they don't think about the potential consequences."

Stephanie says she flirts via text but does not go further because of the possible fallout.

"I've been on the receiving end, having been sent a photo during a normal conversation with someone who I thought was a friend. And then I was begged to send one back. To be honest, it's demeaning having someone beg for something like that, and I didn't want to see what he sent me! Unless you're in some sort of relationship with someone, I find sexting quite cowardly as well."

In her final year of school, Penny, 18, has been sexting, too - both text and images - and says a third of her friends do the same.

"I've personally only sent images to someone who I was in a long-term relationship with and really trusted, so I knew it wouldn't go any further but I think most people do send images without thinking," she says. Of course, she sometimes worries about consequences but her friends seldom discuss sexting, although some may tell close friends, Penny says.

"If messages are sent and images become viral, however, it is definitely a hot topic of conversation," she adds, citing a younger student whom she mentored during a school camp.

"She repeatedly sent raunchy photos of herself to various boys sometimes over Skype but most of the time by SMS and Facebook. They soon went viral and the whole school was talking about her behaviour. Someone even uploaded her photos on the school general computer drive making them accessible for any staff member or student."

Despite complaining, the girl didn't seemed humiliated by the exposure, says Penny, who advised her to be more careful and to talk to a teacher.

"I assume she was asked to leave the school as she left quite abruptly after the incident."

Professor Mitchell says that while sexting can go wrong, it has been fairly harmless for most children who use it.

"We have used the fear of legal sanctions to discourage young people from sending nude or near nude photos and videos," she says, but adds that figures show that this approach has not worked as sexting has become common behaviour.

So how should parents be talking to their teens about relationships and social media?

Mitchell suggests that we should focus on encouraging children to behave ethically towards one another and to take care of themselves and their reputations.

"If teens are using social media, they are likely to be using it for sexual relationships as well. But we found … that most young people were happy about the sex they were having, or not having … So I would advise parents to respect the choices of young people, but to keep the lines of communication open so that problems can be comfortably discussed if they arise."

Stephanie echoes the sentiment, saying family communication is key.

"My relationship with my parents has kept me out of lots of unfortunate teenage experiences. And my friends who have open relationships with their parents don't feel the need to rebel and to keep things hidden," she says.

Penny adds that parents should remind teens of the repercussions of sending inappropriate images.

"It is a very intimate thing to do, so you need to be careful, or you will put yourself in a vulnerable position. I think a lot of younger people do it for attention and parents should be worried about that kind of behaviour. Remember, if the image goes viral, there are long term impacts as the images can be saved … this has the capacity to ruin your self-image and reputation for a very long time."

As a teacher, Penny's mother, Jennifer, is conscious of how strongly teenagers want to fit in with their peers and that it's very hard not to follow if their group of friends is into sexting.

But teens should realise that sexting is "not an affirmation of trust or commitment in a relationship", in fact, it just leaves you vulnerable to manipulation.

The bottom line is teens need better understanding of the power of social media, she says.

Still, Jennifer recognises that warning young people about the negative outcomes of sexting doesn't always work.

Parents need to teach their children how to make informed choices, but that is easy to write and hard to implement, she says

"You must be able to talk to your children and as a teacher, this is equally true - lines of communication have to be set up early on," she says.

Like most parents, Suky assumed her 17-year-old, Ben, wouldn't take part and if he did it would be just a flirty line or two.

But her son became embroiled in trouble when a girl sent a Snapchat picture of herself with very little clothing to a boy at his school here.

"The image was forwarded to about 10 other children, including Ben. In the end it spread to dozens more students. The school acted quickly and I believe the girl and the boy she sent it to were both suspended.

"For Ben, he had a serious talking to at school and at home and it has taught him a tough lesson. Up until this incident we hadn't talked about [sexting] much at home, so that would be my advice to parents - talk to your kids," Suky says.

"It is happening, no matter where they go to school or university and they have to be made aware of what can go wrong."