As child psychologists learn more about the way kids’ brains develop, they’re unearthing clues about how that development is shaped by outside forces. Discipline remains chief among those forces, as the way kids come to understand punishment is, in turn, reflected in their adult actions.

“Tough love” used to mean a firm yet restrained open-handed smack on the behind. That was requisite. Kids with especially strict parents may have gotten a belt or a ceremonial paddle. Today, parenting best practices dictate that spanking is a “no-no.” It’s child abuse, some say, and it has no place in a safe and loving home. In fact, academic research agrees with the trend. Spanking has been found to make kids more aggressive, more prone to weight gain, and more likely to suffer from a raft of other diseases.

The Dangerous 30 Percent

A new study finds these expert warnings may do little to convince parents not to spank their children. Researchers from the University of Michigan examined 2,788 families from an urban area, and when asked whether they spanked their 1-year-old infant within the past month, 30 percent of mothers and fathers reported that they had, with either both parents agreeing or just one.

Overall, Child Protective Services (CPS) involvement linked positively with parents that spanked their kids. During the study period, 10 percent of families received at least one visit from CPS. Despite the small ratio, the research team argues the snapshot is indicative of a far larger problem in the U.S.

"Intervention to reduce or eliminate spanking has the potential to contribute to the well-being of families and children who are at-risk of becoming involved with the (social services) system," said co-author and Michigan professor of social work, Shawna Lee, in a news release. These interventions are designed to protect children from the risky futures laid out by a discipline regimen based entirely on spanking.

Kids whose parents use spanking to lay down the law were found in one 2013 study to be demonstrably more aggressive and under-performing academically than kids whose parents used alternative techniques. Looking at children between 3 and 5 years of age, the researchers found 57 percent of mothers and 40 percent of fathers engaged in spanking, with maternal spanking associating with aggressive behavior by age 9 and paternal spanking associating with lower vocabulary scores by age 9.

What’s more, a separate study found mental health isn’t the only attribute to get caught in the crossfire. Parents who spank their kids could be putting them at risk for physical ailments — one study found a 24 percent greater risk for obesity later in life and a 35 percent added risk for arthritis.

What Can Be Done?

All of this evidence points toward targeted strategies to reduce spanking. Legislation is one route: Before a 1976 ban, more than half of parents in Sweden spanked their kids. By 1996, the rate had fallen to 11 percent. Another route is education. A lot of the time, parents who spank their kids lack the proper language tools to communicate exactly why the child’s behavior was wrong, explains Professor Elizabeth Gershoff of the University of Texas at Austin. In turn, kids never learn to communicate either.

"When (children) want another kid's toy, the parents haven't taught them how to use their words or how to negotiate,” Gershoff told Reuters Health. So the kids resort to the only form of coercion they know: violence.

Spanking, at its core, teaches quick and crude modes of discipline. It sends the message that when something goes wrong, someone deserves to get hit — that words not only won’t suffice, but can’t. "Spanking models aggression as a way of solving problems, that you can hit people and get what you want,” Gershoff said.

Ultimately, if parents want to discipline their children without whipping out the belt, paddle, or hand, they should consider empathy and understanding, along with verbally narrating the child’s feelings so he or she understands what’s going on.

"Acknowledge out loud that you see your child is angry,” psychotherapist Dr. Fran Walfish told Medical Daily. “Say with warmth, sincerity, and empathy, ‘I see you are angry at me. I'm the kind of mom who really wants to hear about it right to my face. Tell me more about how mad you are at me.’"

Parents should also create boundaries and equip children with coping skills, Walfish says. Love is important, but so are limits. And that applies for both children and their parents.