Though Americans have lived through more than 30 school shootings since Columbine in 1999, few have received extensive coverage in the media. Until the tragedy at Sandy Hook Elementary School, when most Americans thought about violence, they might well have turned to the frequent tragedies of Afghanistan and Iraq.

Understandably, the Newtown massacre of 6- and 7-year-olds generated almost unprecedented anxiety about threats to our own children. We cannot remember such a level of anxiety and fear in schools and communities and country. If we cannot protect our children — the most vulnerable among us — who are we?

The confluence of madmen and guns is disastrous. Following each of the major school shootings across the nation, the conversation about firearms and mental instability has filled the media to the point that strangers passing in a grocery store exchange informal remarks on gun control as if they had all just exited a lecture on the topic. Harder to talk about is the madmen side of the equation. But this is where the real conversation needs to take place. Clearly gun control is a critical issue, and we must do all we can to employ adequate background checks and to keep firearms out of the hands of children and emotionally unstable adults. The common denominator we too often overlook in these events is the pervasive question of “Why” and the central role of the human brain in the answer.

How and why can a baby develop into a vicious killer? And what can we do about it?

Perhaps the person who answers this most succinctly is Dr. Bruce Perry, director of the Child Trauma Academy in Houston. He tells us: “It’s not the finger that pulls the trigger; it’s the brain. It’s not the penis that rapes; it’s the brain.” Violence begins in the brain, and the brain begins in the womb.

All behavior, pro-social or anti-social, is controlled by a physical organ — the brain. That brain is fundamentally built within relationships, beginning with the mother during gestation. Brains are built through stimulation. Experiences of all kinds literally stimulate electrical connections among brain cells as well as build gray matter in the brain.

The stimulation a baby experiences before birth and in the first years of life shapes the type of brain the child develops. Those years are simply for developing capacities. An inadequate or traumatic caregiving relationship is deeply damaging, especially during those early years when the brain is forming chemically and structurally. That part of the brain that allows the baby to feel connected with another person can be lost or greatly impaired.

A child can emerge lacking the ability to attach or to resonate in any profound way with others, rendering that child emotionally and significantly damaged. This part of the brain, built primarily through a caregiving relationship, is central to a child’s ability to modulate fear and other emotions. Absent adequate nurturing by an emotionally competent caregiver, the baby faces an unpredictable tide of unregulated emotions.

To build this critical part of human function requires time and a quality of care that we too often overlook in our culture. But know that if a baby’s experiences are pathological and steeped in chronic fear early in development, the very capacities that mitigate against violent behavior (including empathy, the capacity for self -regulation of strong emotions and the emotional modulation essential for complex problem-solving) can be lost.