I was recently asked a question about what’s the right age to start allowing kids to use social media.

The first thing I will say is that nobody under 13 should be using Facebook, Instagram, Snapchat, or Twitter. That’s the minimum age those platforms set for joining.

A lot of parents permit kids to do it anyway but that’s not something I agree with at all. That doesn’t mean I think all 13-year-olds are ready for social media. It’s a big, bad world out there and kids’ do not yet have fully-formed brains.

Even if you think your kid is mature enough to handle it, I’d suggest you not set the example that breaking the rules of the site is a good idea. If you don’t have to follow the age rules, why follow any of them?

Here’s my rule of thumb. Do you think your kid is capable of getting on a bus and going across town alone? Or even better, getting on the subway in New York City and going across town alone. Like social media, the subway is full of mostly nice people with good intentions, and a few bad ones. Would your kid know not to be led astray by strangers? Could he think well enough to resist any temptations that might come into his path? Is she experienced enough to know to go for help if something that makes her uncomfortable happens?

Because when you unleash a kid on social media, you are putting them on a subway car with a world full of people who can easily pretend to be anyone or anything. And while most people on social media are okay humans, some of them are professional creepers who specialize in targeting kids.  And it’s not just bad adults. Kids can be mean. Even meaner with the anonymity that social media provides. Kids can also be sensitive to meanness. Opportunities to bully others or be bullied shoot up because everyone in the world is coming home with you every night.

Mind you, I’m a fan of social media. I’ve made some wonderful online friends who have turned into real-life friends and coworkers. But social media didn’t come along until I was comfortably ensconced in middle age with a lifetime of experience behind me to guide my choices.