Many parents share photos and videos of children on social media: birth announcements, making (an adorable) mess at the dinner table, milestones like a first step.

But there are potential dangers to constantly posting about your child online, says Leah Plunkett, a faculty member at Harvard Law School who specializes in children, family law and technology. In Plunkett's 2019 book Sharenthood: Why We Should Think Before We Talk About Our Kids Online, she explains how adults can put children's privacy and personal data at risk.

This phenomenon is called "sharenting," says Plunkett. Legal scholars in her field use the term — a portmanteau of "sharing" and "parenting" — to describe "all the ways that parents, aunts, uncles, teachers, coaches and other trusted adults in a kiddo's life transmit children's private information digitally." It can make kids vulnerable to identity theft and harassment. And as they grow older, it may undercut their ability to tell their own story.

Plunkett talks to Life Kit about the different harms of oversharing, how to post information about your kid safely and how to talk to loved ones about your limits. This interview has been edited for length and clarity.

Parents share a surprising amount of data about their kids online. A birthday photo, for example, can reveal a kid's name, age and date of birth. What are some of the privacy concerns around that?

There is a thriving black market for personally identifiable information. Kids' Social Security numbers, when combined with date of birth, name and address, are often good targets for identity theft. Most minors don't have credit attached to their Social Security numbers, so [someone may be able to use them to] open fraudulent lines of credit.

Creditors don't verify the age of applicants, so a bad actor could potentially open a credit card without anyone noticing until the kid becomes an adult and wants a card of their own. What are some other security risks?

There are tragic cases of stalking, bullying and harassment. They are rare but they do happen.

So someone could use social media to figure out where your kid lives, goes to school and their patterns and routines. They could also learn about their likes and dislikes and use them in an insidious way.

Other people don't need to have information about the ins and outs of your child's emotional and personal life.

You write in your book that children's data is a form of currency. And there's the adage that if a product is free, you are the product. What should adults think about when giving a company their child's data? Or when reading the fine print on a social media platform?

Parents should be aware that they're not going to know at the moment where a piece of information, photo or video, might go. When we click "I accept," those agreements give companies and third parties a lot of latitude about what they can do with your data.

After my book came out, The New York Times ran a big investigative piece about the ways in which social media photos of toddlers and young children had been surreptitiously used to train facial recognition software. That's one of many examples.

Also, at some point down the road, maybe somebody makes a decision about your child based on the stuff you've put out about them — how your child is doing at school, how they're moving through the world. Maybe that is an individual human decision maker. Maybe that is an algorithmically driven data analysis product.

And when you mean decision makers, that could be a university recruiter or a hiring manager. And that may affect your child's ability to tell their own story.

To themselves or to others in the future. If the world is figuring out significant things about who they are online and making projections about who they're going to be, it can undercut their ability to figure that out for themselves.

Reading your book, it's clear you're not like a Luddite. You have kids, but you haven't sworn off social media. How do you avoid oversharing the digital realm?

Since I started researching this topic, I adjusted my own personal compass to be very minimalist. I pretty much never post my kids on social media. If I do, you don't see their faces or anything that would identify them. I don't use full names. I don't celebrate their birthday on social media. I don't show the kids standing in front of where they go to school.

I follow a "holiday card-or-less" rule of thumb when sharing on social media: updates you'd be comfortable with anyone, from your great aunt to your boss, seeing. Information that's not going to embarrass anybody and isn't particularly private.

Personally, my wife and I are pretty tight about the pictures we share of our kid. How do we prevent other people, like family and friends, from taking photos of them at, say, a baptism or a birthday party, and posting it online?

For something like a baptism or another rite of passage, it's probably impossible to get everyone to not celebrate their joy and pride by taking out a phone. But it is OK to make a gentle request. You might say: Thank you so much for being in this moment with us. To really be in the moment, we would request that you refrain from pictures or videos.

Some people will listen, some people won't. Then make the call about whether or not it matters enough to you to follow up privately with the people who you see taking pictures and videos.

How do you model digital consent with your kids?

The conversation starts with very young kids. Explain what you're doing, why you're doing it and where the image or video is going. You might say something like, "Hey, we're having a really great meal. We're using a recipe your grandfather sent us. I'm going to take a picture for him. Everybody smile for grandpa."

You could also ask your kid at a pretty young age, "are you OK with taking a photo? Anyone not feeling up for it?"

What questions should parents ask themselves before they hit post?

Are you posting a picture of your child in any state of undress? If you are, please don't post it.

Are you sharing your child's location, full name or date of birth? If you are, think about whether that level of detail is necessary for your post.

If your parents shared a similar post about you at this age, how would you have felt about it? If the answer is that it would have really bothered you, take another minute to think about what you need from this post.

What advice do you have for parents who often share photos and videos of their children and their lives on social media? Is it too late for them?

I had the same reaction when I started researching all of this, and I'm here to tell you, take a deep breath. Don't panic. If you want to change, go back over your social media posts and take down what you're not so sure about. Then make your settings private.

Please don't be hard on yourselves. Since the dawn of time, parents have been making the best choices they can at any given moment, and then later being like, maybe I'll do that differently going forward.

The digital story was edited by Malaka Gharib. The visual editor is Beck Harlan. We'd love to hear from you. Leave us a voicemail at 202-216-9823, or email us at LifeKit@npr.org.

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Tags: social media  Social Security  identity theft  posts  life kit  kids online  Life Kit: Parenting  Series: Life Kit