While I lived in Saudi Arabia, drivers of our compound’s shopping bus were given a new rule: drive only on major roads. Yes, Riyadh traffic is terrible. Yes, the main roads at midday are snarled and slow, and the trip back home from many typical destinations could run close to an hour. And yes, you could save a lot of time by cutting through a neighborhood here and there.

This rule wasn’t instituted as a gesture of respect for neighborhood residents, or to keep buses from going over unnecessary speed bumps. No, it happened because schoolboys, at dismissal time in neighborhood schools, were stoning the bus as it passed.

Kids get in trouble everywhere. But throwing stones—not at any and all passing vehicles but at commuter buses with darkened or curtained windows, which are known to carry foreign women—is a VERY specific kind of trouble to get into. It isn’t random.

It sure is natural to think, “What, exactly, are they teaching inside that school?”

When kids get in trouble, it’s usually because they’re pretty focused on themselves and the present moment. They get in fights over stuff they want. They steal candy. They bully to elevate themselves. They do things that are innately exciting or fun, even if they’ve been told not to, because they haven’t thought the slightest about what will happen after the fun part. They don’t have existential enemies. It takes adults to teach them to hate and fear people with whom they’ve had no personal interaction.

So what, exactly, are they teaching inside those schools?

Hatred and aggression toward people you don’t know takes some training. When someone shoots up a mosque or a European nightclub, we ask, “Where was he radicalized?” It’s irrational to harm people who are not harming or threatening you, personally, intimately, imminently. It’s radical. We need to explain this aberration by identifying the source. Surely somebody else, with a larger motive, is responsible. The violence is too focused on something that doesn’t have a rational root to have sprouted up spontaneously within a person.

When it comes to those from other cultures, we find it quite easy to identify the source of radicalization. Schools, madrassas, violence-espousing religious leaders, online recruitment communities.

And yet when the same offences are committed by a man (yes, a man, too often to pretend otherwise) who grew up in our own culture, we don’t ask that question. “Where was he radicalized?” What kind of a question is that? In his own head, obviously. Of course the culture can’t be responsible. I mean, I come from that culture and I’m fine. He’s deranged. He’s not well. He’s a crazy, nut-job aberration in a vast population of people who are fine.

Guess what? They did that in Saudi Arabia, too. If someone from another country—or worse, a non-Sunni stripe of Islam—acted out in violence, Saudi media labeled him a terrorist. If the perpetrator was a Sunni Saudi, he was mentally unwell.

Halloween quiz: A babysitter starts getting frightening calls asking if she’s checked the children. She calls police, who trace the call and tell her the calls are coming from inside the house. Name that movie.

(When a Stranger Calls, 1979. Also 2006 for bonus points. I’m not watching either one.)

My fellow Americans, the children are in trouble, and the killer is inside the house. We are waaaay past the point of forgivable excuses for denying the sources of our own violence. While we insist on deploying perimeter security, the killer is inside the house. While we train guard dogs, the killer is inside the house. While we install camera doorbells and congratulate ourselves on avoiding Girl Scout cookie temptation, the killer is inside the house.

This past Saturday a man opened fire in a crowded Pittsburgh synagogue, killing eleven, wounding four police officers and two others, and leaving an unknown number with trauma and psychic damage that may never heal. This happened the day after another man was arrested for sending bombs through the mail over the past week to political and media figures.

Where were they radicalized? We have to ask ourselves the same question we ask everybody else. Focused violence against people who are not your personal adversaries is not natural. It doesn’t just bloom out of nothing. Children don’t throw rocks at busloads of women who weren’t taught to hate those buses, those women, those foreigners that they don’t even know. And men don’t shoot congregations of worshipers, or send bombs to political figures, who weren’t taught that those targets were bigger, more personal enemies than they appear to be.

Yes, taught. Adults are taught as easily as children. People everywhere, through every era, have the same weaknesses, and one of them is the ease with which we let somebody tell us what to think and do. We are desperate for connection, and when a voice of authority from within our tribe tells us what to think and do, we find a way to think and do it. (Think that only applies to other people? Read about the Milgram experiment.)

Words are telegraphed signals of what binds the tribe. And there is no binding force easier to access or more powerful in cementing those bonds than shared enemies. Sure, most tribal members will agree who the enemies are and let it go at that. They might feel uncomfortable about it, but the psychic comfort of belonging to the tribe will outweigh the discomfort nagging at their souls. Others will bully, troll, and abuse. And some will kill.

When tribal leaders signal to Sunni Muslims that Shia are worse than infidels, most people do nothing, some bully and discriminate and abuse, and some are primed to act out in violence. When tribal leaders signal to American conservatives that journalists are enemies of the state, that white Americans are under attack by non-whites or non-Christians, most people passively agree and go no further than making occasional jokes about Mexicans among friends to signal their own allegiance. Some people bully and troll and make enraged tweets or Facebook posts. And some kill.

American killers are being radicalized by American discourse. Just because you aren’t feeling especially radical doesn’t mean the discourse isn’t the problem. The call is coming from inside the house.

If your religious group claims sole possession of rightness while everybody else is wrong and in the service of Satan…the call is coming from inside the house. If your political tribe is telling you that you’re under attack, that everyone who differs from you is an enemy, if it normalizes name-calling…the call is coming from inside the house. If anybody tells you to reject outside information, to trust no one but them to tell you the true state of things you can’t observe for yourself, an abuser is manipulating you. The call is coming from inside the house.

And when a boy king picks up a signal from an older boy king that they share an enemy, and that he has tacit approval for eliminating that enemy in a third country, and then outrage fades when a new horror replaces it, and an international wink-wink remains in place—the same call is coming from inside a rabbit’s warren of houses.

America, stop imagining that the phone only rings next door. The call is coming from inside the house. And it’s not an enemy intruder upstairs who’s dialing. It’s family.

(Note: The “I’m Fine” image is a sticker available at Redbubble.com)