Helena Duch is a child clinical psychologist and assistant professor of Population and Family Health at the Columbia University Mailman School of Public Health.

Donald Trump signs a girl’s hand at a campaign event in Orlando on March 5. (Jabin Botsford/The Washington Post)

My 9-year-old son despises Donald Trump. So do all his friends. Which isn’t much of a surprise, given that we live in liberal Brooklyn, where the sentiment is shared by young and old. Their dislike, of course, has little to do with Trump’s policy proposals — to kids, he’s just an obvious, garden-variety, loud-mouthed bully.

As both a clinical psychologist and a parent, I think their assessment, and their antipathy, make total sense, but I see something worse. Trump is helping to normalize bullying and negative behaviors as acceptable forms of interaction, instead of modeling positive, self-regulatory skills that eventually help children lead successful, well-adjusted lives.

I just hope Trump supporters realize, before it’s too late, whom they’re on the way to electing as role-model-in-chief.

No one in this election cycle is safe from his insults — from mocking fellow candidate Carly Fiorina’s appearance by saying, “Look at that face, would anyone vote for that?” to smearing Mexican immigrants as “rapists.” And since Trump keeps rising in the polls, there’s no sign that he’ll let up. One result, as The Washington Post’s Petula Dvorak notes, is that his vitriol is quickly seeping “into the lingua franca of children.”

[‘Trump Effect’ is contaminating kids and could resonate for years]

It’s behavior that, when I was in clinical practice, was exactly the sort of thing children were referred to me for displaying, and that I was tasked with trying to address: interrupting others when they speak, belittling and making fun of them, lying consistently and not taking responsibility for their actions. Children who display these behaviors are considered disruptive in school, often not well liked by their peers and likely to be referred to services. And we know from research and clinical experiences that if the behaviors aren’t addressed by professionals and parents, these children may have fewer chances of positive academic, social and economic outcomes.

The reason? Operating with the Trump skill set interferes with the development of foundational skills — frequently termed self-regulation — that include, among other attributes, self-control, appropriate expression of emotions and consideration of different points of view. Those are all keys to our well-being and overall success in life. It might be funny for some to imagine themselves as a trash-talking billionaire, but most people have to be capable of conducting positive interpersonal interactions needed in every setting from Thanksgiving dinner at an in-law’s home to day-to-day life in a corporate cubicle farm.

Research by scholars like Ellen Galinsky or Walter Mischel shows us how these positive foundational skills form the basis of “doing well at school” “thriving as adolescents” and helping them “make choices that allow them to make the most of their lives.” In his enlightening book, “How Children Succeed: Grit, Curiosity and the Hidden Power of Character,” reporter Paul Tough provides extensive support for the key role of these skills as a basis for children’s lifelong success. Writes Tough: “What matters most in a child’s development … is whether we are able to help her develop” a list of skills that includes “persistence, self-control, curiosity, conscientiousness, grit, and self-confidence,” among other life skills, including perspective-taking and gratitude, that tend to make for happier, better-adjusted children who later become better-adjusted adults.

Parents understand, instinctively, that children who lie, belittle, exclude, discriminate or disrespect others will struggle. In over 10 years of clinical and research work in early childhood, I have never come across a parent who tells me that they want their child to become a bully, or intolerant of others. On the contrary, in a survey of preschool parents that my research partners and I conducted last year, 85 percent think it is most important that children in preschool learn to get along with other children, follow directions and pay attention to teachers. In sum, most parents want their children to become good citizens, who share good values and are respectful of others.

By contrast, the kind of bullying that Trump deals in is associated with increased anxiety and fearfulness in children who are exposed to it. Children who witness others being bullied have no reason to believe that they might not be the next victims, and their environment becomes an unpredictable and scary place. Alternatively, witnessing bullying may incentivize students to join in the aggression as a coping strategy for avoiding victimization. When bullying is displayed by those in power, the sense of fear and uncertainty are magnified, as is the modeling of bullying as acceptable behavior. Routinely witnessing Trump’s bullying normalizes the behavior for children and further promotes it. We have examples of it already, with Trump’s behavior encouraging children to chastise, mock and exclude their peers, particularly immigrant children.

We also have evidence illustrating the importance of experiencing failure as a way to overcome and learn from it. Children who wind up being sheltered from failure have difficulties later in life when they inevitably encounter unsuccessful experiences. Trump, like everyone else, has had his share of failures, but his inability to acknowledge or reflect on them again shows how he’s a poor role model for our children.

[Trump’s bad casino bet]

There are proven educational programs dedicated to teaching children to be reflective, make mistakes and learn from them, respect difference and follow basic social rules. So the more we elevate Trump, the more we’re hurting efforts to help kids learn the skills they need. Given the amount of time that our political leaders, particularly the president, are seen and heard on TV and in other media — which kids undoubtedly absorb — if we’re stuck with a “leader” like Trump, even through Election Day, let alone for four or eight years, his is the role-modeling our children would be presented with.

Schools, parents and communities at large don’t and shouldn’t tolerate bullying, dishonesty and bigotry in children. We shouldn’t accept them from candidates either. For this reason, apart from the various issues being debated in this election, parents need to demand that candidates lead, not just by example, but an example that helps kids.

Those who endorse and vote for him are presenting children a blueprint for, at best, boorishness, and, at worst, failure.