As these children grow into adolescence and adulthood, impulsive and aggressive behaviors are so often the outcomes. Moreover, genetic proclivities toward mental illness also are exacerbated. Communities inevitably absorb the consequences. We ignore the root of the problem at our peril.

While earliest development furnishes the greatest moments to do the most to prevent violence in our communities, there will always be children who slip through the cracks. For children, like the young adult shooter in Newtown who was so clearly estranged and emotionally needy, the mental health system in our country is almost nonexistent. Meanwhile, the parents of these children are most often left to fend for themselves in trying to get help.

We watched in horror as the Newtown, Conn. story unfolded. Imagine. Twenty first-graders massacred in an American school. Thus, in addition to conversations about gun control and a mandate to renovate and expand mental health services, it is also time for another conversation — that of building healthy brains from the beginning of life, and nurturing and intervening to prevent developing madmen in our midst.

We are learning the hard way that mental and physical well-being are inseparable. Children who are attached and empathic with other people, who can self-regulate strong negative emotions and can use their minds to focus on complex problem-solving won’t be attracted to aggression and violence, or to using guns to maim or massacre and murder other people.

It is time to make the connection.

Robin Karr-Morse is a therapist in Portland, Ore. and author of “Scared Sick: The Role of Childhood Trauma in Adult Disease” and “Ghosts from the Nursery: Tracing the Roots of Violence.” David Lawrence Jr. is president of The Early Childhood Initiative Foundation and education and community leadership scholar at the University of Miami School of Education and Human Development.