As Facebook lifts its sharing restrictions on 13-to-17-year-olds, Jon Henley finds that young people know exactly what to do with their privacy settings – especially where Mum is concerned

They share, like, everything. How they feel about a song, their maths homework, life (it sucks). Where they'll be next; who they're with now. Photos, of themselves and others, doing stuff they quite probably shouldn't be.

They're the digital natives, fresh-minted citizens of a humming online world. They've grown up – are still growing up – with texting, sexting, MSN, Facebook, Vine, Snapchat. They're the young, and they couldn't care less about privacy.

At least, that's the assumption. But amid a rash of revelations about government surveillance, it seems it's wrong. Young people do care, a lot, about privacy – just not the kind of privacy that exercises their parents.

True, young people post information about themselves online that horrifies their elders. A report in May by the Pew Internet and the American Life Project found 91% of the 12-to-17-year-olds it surveyed post photos of themselves (up from 79% in the last such survey, in 2006) and 24% post videos. Another 91% are happy posting their real name, 60% their relationship status, 82% their birthday, 71% the town where they live and the school they attend, 53% their email address and 20% their mobile number (compared with 2% in 2006). And in the UK at least, where the data trends are broadly similar, there remains "a basic lack of awareness" about "the potential longer-term impact of information leaks", says Andy Phippen, professor of social responsibility in information technology at Plymouth University.

"Many younger people just don't think in terms of their future employability, of identity theft, of legal problems if they're being provocative. Not to mention straightforward reputational issues." (Paris Brown, Phippen adds, "clearly never thought what she tweeted when she was 14" might one day stop her being Britain's first youth police commissioner.)

Far more should be done in schools to teach children to be more concerned about the future impact of their online profile and reputation, Phippen argues. But they fact that they make mistakes does not mean they don't care about privacy. "Teens are often involved in a process of identity formation that involves not just exploring different concepts of self, but presenting such identities to others," says Jay Stanley, senior policy analyst at the American Civil Liberties Union. "That's something teens have always done – but today it's done electronically," Stanley said in a blog post. "That may mean identity experimentation has bigger privacy consequences today than for past generations, but it doesn't mean teens don't desire privacy overall."

In fact, the same Pew report found teenagers cared enough about online security for 60% to set their Facebook profiles to "private" and to judge privacy settings "not difficult at all" to manage. A similar number said they routinely delete past posts, block people, and post comments only particular viewers – typically, close friends – would understand.

"You have to think about what privacy means," says Danah Boyd, a leading youth and social media researcher. "What matters to them is social privacy: it's about how to control a social situation, which is something very different from controlling information."

The Pew report found that only 9% of teens were "very" concerned about third parties like companies or government agencies accessing their personal information – compared with nearly half of their parents. Most young people have precious little idea of how much data social networking sites are collecting on them – but they tend, on the whole, to be quite relaxed about the idea, particularly if it comes as a trade-off for free use of the service.

Teens, Boyd says, tend to be concerned not by unknown third parties accessing data about them, but by "things that might be seen by the people who have power over them: parents, teachers, college admissions officers. The concern is more about your mother looking at your Facebook profile … than government agencies or advertisers using data you've shared."

Young people are concerned, in other words, about getting into trouble. But that concern is every bit as real. So teens now manage their online security with "a whole set of strategies", says Boyd. Many don't tell the truth online: according to the Pew Internet study, 26% of teen social media users say they post fake information like a false name, age or location. Others are more subtle. Boyd uses the term "social steganography" to describe the practice of more than 50% of young people who use in-jokes and obscure references to effectively encode what they post.

"The point is to allow access to the content, but zero access to the meaning," she says, citing the example of a teenage girl she recently interviewed who had just broken up with her boyfriend, was feeling truly awful, and badly wanted to say so – but without her mother finding out. "Teenage girls express what they're feeling by putting up song lyrics," Boyd says. "This one put up Always Look on the Bright Side of Life. Her friends knew it was sung from the crucifix, but her mum didn't get it. In fact, her mother posted the comment, 'Looks like you're having a great day!'"

Context is all in social media, which poses a challenge when it comes to privacy. Teens' impulse is "to connect, to hang out. For me, the place for that was in the mall; they do it online, and it leaves traces," says Boyd. "No one can imagine all the possible interpretations of everything they say online."

Nonetheless, says Mary Madden, co-author of the Pew Internet report, all the signs are young people today are increasingly "practising good judgment. They'll say, 'I use a filter in my brain'; they do a lot of profile pruning, deleting and editing content, deleting tags. There's a new awareness." This generation has, after all, "grown up, learned to function in a world of social surveillance", says Madden. "Far from being privacy-indifferent, they are mindful of what they post. They have a sense that adults are watching."

That sentiment may in part explain the recent popularity of new social networking services like Instagram and Snapchat, says Madden: "Some feel the burden of the public nature of social networking. They're creating smaller groups with these new services."

Snapchat in particular appeals because it allows users to send annotated pictures, videos and messages to a controlled list of friends – and, crucially, to set a time limit for how long they can be viewed before they disappear and are deleted. Overall, confirms Madden, "We're seeing a pattern that runs counter to the assumption that there's this sea of young people who just don't care about privacy. It's not borne out by the data. And in some cases, they actually have stronger opinions than some adults."

That certainly seems to be the picture emerging from two polls conducted earlier this year by the Pew Research Centre for the People and the Press with the Washington Post and USA Today, in the wake of Edward Snowden's revelations about broad surveillance by state security services.

In the first of these polls, on 10 June, younger respondents proved much more likely than older to put personal privacy above an anti-terrorism probe: 45% of 18-to-29-year-olds said personal privacy was more important, even if protecting it limited the ability to investigate terrorist threats – compared with 35% in the 30-to-49 age range, and 27% of the over-50s.

The second poll, on 17 June, asked whether Snowden's leaks of classified information about the NSA's phone and email surveillance programmes was in the public interest. It found that people under 30 were the only age group in which "a clear majority" – 60% – felt the revelations served the public interest. Older age groups were either divided, or thought the disclosures harmed the public interest. Similarly, 13-to-29 year-olds were less likely to feel Snowden should be prosecuted: fully 50% felt he should not be, against 44% who thought he should. That compares with 63% of over-50s who wanted see the whistleblower pursued.

Carroll Doherty, co-author of the second report, said previous surveys showed also that younger people – perhaps because they came of age after the 9/11 attacks – were generally less anxious about the risk of terrorism, and less likely to be concerned about the rise of Islamic extremism. Even after the Boston attacks earlier this year "made young people more aware of threat", Doherty says, recent polling shows they still remain "less likely to link Islam to terrorism, and less likely to say that government should investigate threats at a cost of personal privacy". There is "quite a consistent pattern here", he says: "Young people tend to take a more liberal approach to issues around security and terrorism."

So should the older generation worry? Stanley of the ACLU thinks not. Many people, advertisers included, are all too happy to create the impression that young people don't care about "silly old privacy concerns", he blogged.

Many privacy invasions, too, "are silent and invisible, and only a minority of people will know and care about them. But where people are aware of their loss of control over how they are seen by others, people of all ages will always assert their need for privacy in the strongest way."