Donald Trump speaks in Fort Dodge, Iowa, on Nov. 12. (Scott Olson/Getty Images)

One of the reasons that Donald Trump has flummoxed pollsters and political analysts is that his supporters seem to have nothing in common. He appeals to evangelical and secular voters, conservative and moderate Republicans, independents and even some Democrats. Many of his supporters are white and don't have a college degree, but he also does well with some highly educated voters, too.

What's bringing all these different people together, new research shows, is a shared type of personality — a personality that in many ways has nothing to do with politics. Indeed, it turns out that your views on raising children better predict whether you support Trump than just about anything else about you.

Matthew MacWilliams, a doctoral candidate at the University of Massachusetts, Amherst, conducted a poll in which Republicans were asked four questions about child-rearing. With each question, respondents were asked which of two traits were more important in children:

  • independence or respect for their elders;
  • curiosity or good manners;
  • self-reliance or obedience;
  • being considerate or being well-behaved.

Psychologists use these questions to identify people who are disposed to favor hierarchy, loyalty and strong leadership — those who picked the second trait in each set — what experts call "authoritarianism." That many of Trump's supporters share this trait helps explain the success of his unconventional candidacy and suggests that his rivals will have a hard time winning over his adherents.

When it comes to politics, authoritarians tend to prefer clarity and unity to ambiguity and difference. They're amenable to restricting the rights of foreigners, members of a political party in the minority and anyone whose culture or lifestyle deviates from their own community's.

"For authoritarians, things are black and white," MacWilliams said. "Authoritarians obey."

While some scholars have argued that authoritarianism is associated with conservatism, there are certainly authoritarians in both parties. And MacWilliams found that the likelihood that participants in his poll supported Trump had little to do with how conservative they were — no surprise, as Trump's positions on many issues are relatively moderate.

Trump also appealed more or less equally to the likely Republican primary voters in MacWilliams's sample regardless of their age or sex, income and level of education. Regular churchgoers and evangelicals were no more or less likely to support Trump, either.

Those with authoritarian views on raising children were, however. Among Republicans who are otherwise similar, authoritarians — those who chose the second option in each of the four questions above — have nearly 50-50 odds of supporting Trump. The odds are much lower for those who chose the first option on all four questions: Assuming they were similar in other respects to the authoritarians, the chance that Republicans in this group supported Trump were just 1 in 6.

By contrast, how respondents answered the questions about child-rearing had little or nothing to do with their likelihood of supporting one of Trump's rivals. The authoritarians were somewhat more likely to support Sen. Ted Cruz (R-Tex.) but not by much.

Now, you might think that how a parent raises a child has little to do with how they vote. After all, roughly half of the people with authoritarian views on all four questions did not support Trump.

So MacWilliams checked to make sure that his questions about child-rearing were in fact predictive of authoritarian political attitudes. In the poll, respondents were also asked whether they thought that it is sometimes necessary to keep other groups in their place, whether opposition from the political minority sometimes needs to be circumscribed, and whether they think the minority's rights must be protected from the majority's power.

Trump's supporters were much more likely to oppose protections for the minority, while the other candidates' supporters didn't have strong opinions one way or another. For example, the chance that a Republican who agreed that other groups sometimes need to be put in place also supported Trump was about 3 in 5.

MacWilliams also found that respondents who said they felt threatened by terrorism were also significantly more likely to support Trump, and polling by The Washington Post has found that opposition to immigration is something else that unites many of his supporters. Authoritarians, given their aversion to outsiders, are more likely both to perceive threats from terrorism and to oppose immigration.

That Trump's support is based partly on personality rather than policy helps explain why his supporters are so enthusiastic about some of his most widely mocked ideas — such as banning all Muslims from entering the country, a proposal that his opponent Jeb Bush called "unhinged."

"This is in people's guts, not their brains," said Marc Hetherington, a political scientist and an expert on authoritarianism at Vanderbilt University. "This is much more primal."

And the findings are bad news for the other contenders in the GOP primary, since authoritarians tend to be set in their ways. What they have in common is an aversion to new kinds of experiences. "Some people eat at Thai and Indian restaurants, and some people eat at steak houses," Hetherington said. That aversion could also extend to politicians they don't know as well as Trump.

"It's not worth it to attack him," said MacWilliams, who spent many years as a progressive political consultant before going to graduate school.

"A large segment of his base is like 'granite,'" MacWilliams added, quoting an anonymous adviser to Sen. Marco Rubio (R-Fla.) who was interviewed by Jeremy W. Peters of the New York Times.

Analysts have conventionally divided the Republican primary race into "lanes" — candidates who appeal to evangelicals run in the "evangelical lane," for example. There might also be an "establishment lane" and a "libertarian lane." Some have argued that Trump is taking up all of the lanes at once.

"Maybe the future of the GOP is this one wide, luxurious lane, allowing the Trump steamroller easy passage," wrote The Washington Post's Philip Bump.

Another interpretation is just that Trump has discovered a new lane — the authoritarian lane — that other candidates might seek to exploit in the future.

"Does that become an activated part of the party moving forward or not?" MacWilliams asked. "I think that is a key question. Is it specific to his ability to speak to them and activate them, or not?"

Authoritarianism isn't always a negative trait, noted Vanderbilt's Hetherington. Authoritarians can be more direct and decisive when the situation calls for it. "There's this notion that all the nuanced navel gazing that liberals do is superior," he said. "Not always."

Nonetheless, research on authoritarianism is extremely sensitive, since it began after World War II, when psychologists and social scientists wanted to understand how so many people could support repressive, homicidal dictatorships in Europe and elsewhere.

"I'm not saying they're fascists," MacWilliams said of Trump's supporters, "but authoritarians obey."

Insult after insult flew during the Fox News GOP debate on March 3. Here's a look at some of the choice words rivals Marco Rubio, Ted Cruz and Donald Trump had for each other, while John Kasich stayed out of the fray. (Jenny Starrs/The Washington Post)