Going to buy breakfast this morning, I saw this sign on the wall by the grocery store door. It made me recall an incident from my childhood. I must have been twelve or thirteen. I had walked with a couple of others to a convenience store on a hot day, and we were waiting in line to buy drinks. The young man at the counter told me I needed to leave the store. In disbelief, I asked why. He pointed to a sign on the door, saying that no more than two minors could be in the store at one time. I was the third kid in line, so I had to leave.

I was furious, and I shared some of my newly learned curse words with the clerk, but I left. In an attempt to defend the policy, someone said to me (I don’t recall who), that the sign wasn’t really intended to apply to me, but they couldn’t legally say, “No more than two black kids in the store at one time.”

“What?” I demanded. “What the hell is that supposed to mean?”

“It means that they had a problem with black kids stealing from them.”

Yeah, that didn’t make me less furious. The impulse to assume that all members of a particular group share a common negative trait, or are more prone to bad behavior, is wrong. It’s wrong whether you apply it to all people of color or all people of a certain age. I’m sure some black kid did steal from that store. I’m sure more than one did. I’m sure white kids did too, and, I’m sure, adults as well.

When I was a youth director for a church, one of the kids in my group actually told me that “All kids shoplift. It’s part of growing up.” That’s how ingrained the belief is. Some kids even share it. I told her that no, not all kids shoplift. Most don’t, and most people don’t. It’s bad business (and bad morals) to try and control the behavior of a few by limiting the actions of all. I believed then, and still believe now, that if you want to limit the number of customers in your store so that you can watch them like hawks, you should simply cap the number of people who can enter at all. Or perhaps, like some city liquor stores, you should put all your stock out of reach of the public.

Now the sign on the grocery store was less offensive, I think, than one saying only a certain number of minors could be in the store at all. It said that groups of three minors needed an adult guardian. I suspect that sign was less about controlling shoplifting and more about controlling unruly groups of kids, and even potential gang activity. (Although I imagine the only gang the artificial town of Maple Lawn is likely to be prone to would be a gang of rabid fitness enthusiasts in garishly colored tights.) Having worked as a librarian, I know that large groups of kids can get out of control, and are a challenge for the staff of a public building to handle. But, having worked as a librarian, I also know that we considered it not an option to say that kids couldn’t come into our building. Stores should have the same policy—kids are customers too, after all.

It makes me pause before entering a store that post signs like these. It’s discriminatory and it’s lazy. Yes, kids are more prone to behave outside the lines of what most adults would agree is proper public conduct. Some of them simply haven’t lived long enough to fully adjust to the idea of keeping their voices down, not running, or not throwing things at each other where they might hit bystanders. But, honestly, I don’t find most adult behavior better. Pushing your cart slowly down the middle of an aisle, oblivious to people who might be trying to pass you, parking your cart next to you so that it blocks an aisle, coming around blind corners, with a cart, at high speed, or having a loud break-up with your significant other on your cell phone are all behaviors I’d like to see banned in grocery stores. Can we limit the number of self-absorbed, middle-ages suburbanites who are allowed to enter?

It may not be easy, but businesses—and staff of any public place that people frequent—need to learn to set and enforce civil behavior. I think a lot of store employees would say that’s not part of their job, but they’re simply not accepting the facts. As any librarian can tell you, monitoring and commenting on public behavior is part of the job. And no, it’s not easy.

But it’s better than a sign on your door that tells a segment of the population that they aren’t welcome.