Mark Zuckerberg is very sorry.

His apology at a Senate hearing to the families of victims of online child sex abuse was dramatic, and the human thing to do in the moment, although he was pressured into it under persistent questioning from Sen. Josh Hawley, a Republican from Missouri.

Zuckerberg’s contrition — whether real, fake or somewhere in between — doesn’t really matter one way or the other, though. The key question is why we are subjecting our children to a vast, real-time experiment in exposure to a radically new medium that evidence suggests is harmful to their emotional and mental health.

This dubious venture is unquestionably a boon to the bottom line of Meta and its peer companies, but it’s doubtful that any parent in America has ever thought it was good for their kid. “Gosh, how can I get my tween to spend more time on Instagram?” is, needless to say, a thought most parents don’t have.

Social scientist Jonathan Haidt has been on this case for some time now and points out a marked increase in teen depression and anxiety that coincides with the rise of social media, particularly among girls. It is, to be sure, difficult to nail down with absolute certainty a direct relationship between social media and these distressing outcomes, but many studies find a connection, and the lived experiences of families is, overwhelmingly, that the takeover of adolescence by social media hasn’t been a healthy phenomenon.

At the very least, social media is addictive and represents an opportunity cost compared to time that could be spent talking with friends, going outside or even reading a book.

Congress should press the brakes on the revolution that has given Mark Zuckerberg and other tech titans an outsized role in raising our kids and require that users of social media be age 18 or older. Surely, it’s not too much to ask that Zuckerberg and Co. make their fortunes exclusively off adults.

Congress has already imposed an age limit, just in the wrong place. The Children’s Online Privacy Protection Act prevents the companies from collecting personal information from children under age 13, effectively prohibiting them from social media. But 13 draws the line much too young.

Regardless, the companies have been happy to make a mockery of the rule. About 40% of kids age 8-12 use social media, while usage by teens age 13-18 is nearly ubiquitous.

For social-media companies, these kids are just another market. According to a Wall Street Journal report a couple of years ago, “Inside the company, teams of employees have for years been laying plans to attract preteens that go beyond what is publicly known, spurred by fear that Facebook could lose a new generation of users critical to its future.”

Let’s say the research and everyone’s intuition is wrong, and social media isn’t driving worse outcomes for kids.

What’s the harm in staying off social media until they’re older? That kids will miss out on the latest absurd and perhaps dangerous TikTok trend? That they won’t get to envy people posting photos on Instagram to make themselves look more interesting and beautiful than they really are? That they will talk to their families and friends more and engage in more activities in the real world?

Rich Lowry is editor in chief of the National Review