Mom, Dad, here is your popup warning: Your teen is being wooed by Facebook.

The social media giant is desperately trying to reposition its digital offerings to teenagers. It’s a marketing ploy that has Facebook attempting to pass itself off a bit like an Internet version of a friend’s more lenient parent.

From now on, teens will be allowed to opt out of privacy settings and choose to post publically. This means that adept strangers — including those of malign intent — will be able to view a teenager’s postings, pictures, videos, updates and conversations with friends. Strangers will be able to “follow” a teenager’s timelines.

Facebook announced the changes to privacy settings for 13-to-17-year olds in a blog post. “Teens are among the savviest people using social media, and whether it comes to civic engagement, activism or their thoughts on a new movie, they want to be heard,” it read.

Yes. And they are also hard-wired to have less impulse control, more apt to be controlled by peer pressure, and prone to act first and only realize consequences later.

Never mind that. Log on, create an account, Facebook seems to say. There are few limits here! You can reach lots of people, and they can reach you. Never mind that those new “friends” can include pedophiles and strangers with a penchant to bully and harass.

No doubt about it, Facebook just made it easier for creeps to stalk via the Internet.

The new policy amounts to using the nation’s children as advertising bait. Facing increased competition, Facebook is doing this for advertisers and marketers in an attempt to keep up with Twitter, Tumblr and other newer social media outlets considered far cooler, more hip to younger audiences.

Companies can gather all sorts of information and then reach out to young people and their friends who opt out of the privacy walls.

Oh, sure, Facebook will underline that the changes include one new safeguard. New teenaged users’ settings will by default restrict their posts to friends, not friends of friends, as was previously allowed. But those settings can be changed. A warning onscreen will appear when teens take the option of making posts public. A popup message will let the teen know that “You and any friends you tag could end up getting friend requests and messages from people they don’t know personally.”

A lot of children will think that sounds just grand. After all, isn’t connecting with people who you don’t already know part of the allure of the digital age? Meeting lots of new people online is thrilling to a mindset not mature enough to discern the dangers.

If Facebook carries on with the new policy — and there are few indications it won’t — it’s fair to say that it has just turned in the social responsibility card that once distinguished it from other social media sites. Facebook has always been better than Twitter and other sites at compelling users to post as themselves.

Facebook has defended the policy change for teens on the grounds that it will aid children who are budding philanthropists and artists. These children, goes the rationalization, need to be able to reach wider audiences to do their good works.

That’s a rather weak justification. Everyone knows that Facebook users are not just users — they’re the product being sold.

Coincidentally, Facebook announced the change just as Americans were learning of yet another case of a young girl committing suicide after being bullied on social media. A Florida sheriff cited the Facebook postings of a 14-year-old in charging her and a 12-year-old girl with the felony of aggravated stalking. The two were charged in connection with the suicide of another 12-year-old girl, Rebecca Ann Sedwick.

Rebecca leapt to her death from an abandoned cement factory silo after being targeted for months with cyber bullying, some of it via Facebook.

“Watch what your children do online,” Sheriff Grady Judd was quoted saying in the New York Times. “Pay attention. Quit being their best friend and be their best parent.”

As many parents can attest, monitoring or banning social media in the home does not keep teens from using it. For that reason alone, it would be far more helpful if Facebook and other social media platforms took the attitude that, by default, they are parents, too.