Michael D'Antonio is the author of the new book, " The Truth About Trump ." The opinions expressed in this commentary are his.

(CNN) Every few days Donald Trump challenges us with his obsession with race, ethnicity, religion and gender and with his relentless effort to alienate us from each other.

The latest example finds him telling the Wall Street Journal that the federal judge hearing the fraud complaints against his defunct Trump "University" should disqualify himself because he is of Mexican descent. "I'm building a wall," said Trump, referring to his call for a huge border wall between the U.S. and Mexico, so the judge has "an inherent conflict of interest ."

Trump defended the comments in an interview with CNN's Jake Tapper on Friday, saying: "He's proud of his heritage. I respect him for that," yet adding, "He's a Mexican." In fact, the judge was born in the U.S.

House Speaker Paul Ryan, who only Thursday said he would vote for his fellow Republican Trump, quickly criticized the statement about Judge Gonzalo Curiel, saying, " I completely disagree with the thinking behind that."

Trump's claim about Judge Curiel shows he doesn't understand the first thing about the judicial system, which is based on the integrity of men and women who are charged with keeping their emotions and personal feelings out of their work on the bench.

Even more importantly, Trump's statement is just one of many he has uttered during the presidential campaign, and throughout his life, that reveal a warped perspective on what it means to be a citizen of a diverse country where differences are respected and valued.

It is, of course, only human for us to feel anxiety about people who may be different from us. The tendency to categorize others is a well-established element of human nature. But it is also human to seek to work against our prejudices and to understand that others always deserve respect.

We don't try to turn our negative assumptions into applause lines, or, as Trump did Friday, seek to exploit the racial identities of those we encounter. Trump did this at a campaign rally when he noticed a black man in the crowd and said, into the microphone, "Oh, look at my African American over there. Are you the greatest?"

Swedish, not German?

For at least four decades, Trump has aired rather strange views about heritage and identity. As a young man, he repeated his father Fred's false claim that the Trump family -- the name was once Drumpf -- emigrated from Sweden, and not Germany. The senior Trump began calling himself Swedish after World War II because, as Donald Trump told me, he didn't want Jewish New Yorkers to connect him with the Nazi regime and take their business elsewhere.

This assumption, which Donald agreed with, betrays an exceedingly dim view of human nature. The Trumps expected bigotry from Jewish New Yorkers and they were willing to turn their backs on their ancestors to make money.

As Donald Trump moved through his adult life, he has regularly demonstrated an extraordinary level of concern about the ethnic and racial identity of people he encountered. When he testified before a committee in Congress about competing casino operators from Native American tribes he complained, out loud, that they "don't look like Indians to me."

In his book about Trump's years as a casino operator in Atlantic City, former Trump executive John R. O'Donnell wrote of how his boss made bigoted statements about African-Americans and Jews. O'Donnell quoted Trump saying

"Black guys counting my money! I hate it. The only kind of people I want counting my money are short guys wearing yarmulkes... Those are the only kind of people I want counting my money. Nobody else ... Besides that, I tell you something else. I think that's guy's lazy. And it's probably not his fault because laziness is a trait in blacks."

Trump has both confirmed and denied the accuracy of O'Donnell's reporting. In May 1997, he told Playboy writer Mark Bowden about the book generally, "The stuff O'Donnell wrote about me is probably true." Two years later, when he was eying a third party run for president he told Tim Russert, "I've never said anything like it."

Fair housing case

Prior to Trump's involvement in gambling, his real estate organization was subject to a crackdown by the U.S. government for failing to comply with fair housing laws governing applications for apartments by minorities. Trump answered with a countersuit in which his lawyer likened the feds to the "Gestapo" and "storm troopers."

The countersuit was dismissed by the judge in the case. In the end, Trump settled the case by agreeing to comply with the law and without admitting wrongdoing.

In 1989, he was back in the press again, telling Bryant Gumbel that, "A well-educated black has a tremendous advantage over a well-educated white in terms of the job market."

Foreigners have also come in for Trump's prejudice on a regular basis. In the 1980s it was the Japanese who secretly "laugh like hell" after completing unfair business deals Now it's the Chinese, whom Trump mocks by speaking broken English, but also offers as the wily, if not sneaky, bargainers who take advantage of America.

Photos: Donald Trump's rise President-elect Donald Trump has been in the spotlight for years. From developing real estate and producing and starring in TV shows, he became a celebrity long before winning the White House. Hide Caption 1 of 37 Photos: Donald Trump's rise Trump at age 4. He was born in 1946 to Fred and Mary Trump in New York City. His father was a real estate developer. Hide Caption 2 of 37 Photos: Donald Trump's rise Trump, left, in a family photo. He was the second-youngest of five children. Hide Caption 3 of 37 Photos: Donald Trump's rise Trump, center, stands at attention during his senior year at the New York Military Academy in 1964. Hide Caption 4 of 37 Photos: Donald Trump's rise Trump, center, wears a baseball uniform at the New York Military Academy in 1964. After he graduated from the boarding school, he went to college. He started at Fordham University before transferring and later graduating from the Wharton School, the University of Pennsylvania's business school. Hide Caption 5 of 37 Photos: Donald Trump's rise Trump stands with Alfred Eisenpreis, New York's economic development administrator, in 1976 while they look at a sketch of a new 1,400-room renovation project of the Commodore Hotel. After graduating college in 1968, Trump worked with his father on developments in Queens and Brooklyn before purchasing or building multiple properties in New York and Atlantic City, New Jersey. Those properties included Trump Tower in New York and Trump Plaza and multiple casinos in Atlantic City. Hide Caption 6 of 37 Photos: Donald Trump's rise Trump attends an event to mark the start of construction of the New York Convention Center in 1979. Hide Caption 7 of 37 Photos: Donald Trump's rise Trump wears a hard hat at the Trump Tower construction site in New York in 1980. Hide Caption 8 of 37 Photos: Donald Trump's rise Trump was married to Ivana Zelnicek Trump from 1977 to 1990, when they divorced. They had three children together: Donald Jr., Ivanka and Eric. Hide Caption 9 of 37 Photos: Donald Trump's rise The Trump family, circa 1986. Hide Caption 10 of 37 Photos: Donald Trump's rise Trump uses his personal helicopter to get around New York in 1987. Hide Caption 11 of 37 Photos: Donald Trump's rise Trump stands in the atrium of the Trump Tower. Hide Caption 12 of 37 Photos: Donald Trump's rise Trump attends the opening of his new Atlantic City casino, the Taj Mahal, in 1989. Hide Caption 13 of 37 Photos: Donald Trump's rise Trump signs his second book, "Trump: Surviving at the Top," in 1990. Trump has published at least 16 other books, including "The Art of the Deal" and "The America We Deserve." Hide Caption 14 of 37 Photos: Donald Trump's rise Trump and singer Michael Jackson pose for a photo before traveling to visit Ryan White, a young child with AIDS, in 1990. Hide Caption 15 of 37 Photos: Donald Trump's rise Trump dips his second wife, Marla Maples, after the couple married in a private ceremony in New York in December 1993. The couple divorced in 1999 and had one daughter together, Tiffany. Hide Caption 16 of 37 Photos: Donald Trump's rise Trump putts a golf ball in his New York office in 1998. Hide Caption 17 of 37 Photos: Donald Trump's rise An advertisement for the television show "The Apprentice" hangs at Trump Tower in 2004. The show launched in January of that year. In January 2008, the show returned as "Celebrity Apprentice." Hide Caption 18 of 37 Photos: Donald Trump's rise A 12-inch talking Trump doll is on display at a toy store in New York in September 2004. Hide Caption 19 of 37 Photos: Donald Trump's rise Trump attends a news conference in 2005 that announced the establishment of Trump University. From 2005 until it closed in 2010, Trump University had about 10,000 people sign up for a program that promised success in real estate. Three separate lawsuits -- two class-action suits filed in California and one filed by New York's attorney general -- argued that the program was mired in fraud and deception. Trump's camp rejected the suits' claims as "baseless." And Trump has charged that the New York case against him is politically motivated. Hide Caption 20 of 37 Photos: Donald Trump's rise Trump attends the U.S. Open tennis tournament with his third wife, Melania Knauss-Trump, and their son, Barron, in 2006. Trump and Knauss married in 2005. Hide Caption 21 of 37 Photos: Donald Trump's rise Trump wrestles with "Stone Cold" Steve Austin at WrestleMania in 2007. Trump has close ties with the WWE and its CEO, Vince McMahon. Hide Caption 22 of 37 Photos: Donald Trump's rise For "The Apprentice," Trump was honored with a star on the Hollywood Walk of Fame in January 2007. Hide Caption 23 of 37 Photos: Donald Trump's rise Trump appears on the set of "The Celebrity Apprentice" with two of his children -- Donald Jr. and Ivanka -- in 2009. Hide Caption 24 of 37 Photos: Donald Trump's rise Trump poses with Miss Universe contestants in 2011. Trump had been executive producer of the Miss Universe, Miss USA and Miss Teen USA pageants since 1996. Hide Caption 25 of 37 Photos: Donald Trump's rise In 2012, Trump announces his endorsement of Republican presidential candidate Mitt Romney. Hide Caption 26 of 37 Photos: Donald Trump's rise Trump speaks in Sarasota, Florida, after accepting the Statesman of the Year Award at the Sarasota GOP dinner in August 2012. It was shortly before the Republican National Convention in nearby Tampa. Hide Caption 27 of 37 Photos: Donald Trump's rise Trump appears on stage with singer Nick Jonas and television personality Giuliana Rancic during the 2013 Miss USA pageant. Hide Caption 28 of 37 Photos: Donald Trump's rise In June 2015, during a speech from Trump Tower, Trump announced that he was running for President. He said he would give up "The Apprentice" to run. Hide Caption 29 of 37 Photos: Donald Trump's rise Trump -- flanked by U.S. Sens. Marco Rubio, left, and Ted Cruz -- speaks during a CNN debate in Miami on March 10. Trump dominated the GOP primaries and emerged as the presumptive nominee in May. Hide Caption 30 of 37 Photos: Donald Trump's rise The Trump family poses for a photo in New York in April. Hide Caption 31 of 37 Photos: Donald Trump's rise Trump speaks during a campaign event in Evansville, Indiana, on April 28. After Trump won the Indiana primary, his last two competitors dropped out of the GOP race. Hide Caption 32 of 37 Photos: Donald Trump's rise Trump delivers a speech at the Republican National Convention in July, accepting the party's nomination for President. "I have had a truly great life in business," he said. "But now, my sole and exclusive mission is to go to work for our country -- to go to work for you. It's time to deliver a victory for the American people." Hide Caption 33 of 37 Photos: Donald Trump's rise Trump faces Democratic nominee Hillary Clinton in the first presidential debate, which took place in Hempstead, New York, in September. Hide Caption 34 of 37 Photos: Donald Trump's rise Trump apologizes in a video, posted to his Twitter account in October, for vulgar and sexually aggressive remarks he made a decade ago regarding women. "I said it, I was wrong and I apologize," Trump said, referring to lewd comments he made during a previously unaired taping of "Access Hollywood." Multiple Republican leaders rescinded their endorsements of Trump after the footage was released. Hide Caption 35 of 37 Photos: Donald Trump's rise Trump walks on stage with his family after he was declared the election winner on November 9. "Ours was not a campaign, but rather, an incredible and great movement," he told his supporters in New York. Hide Caption 36 of 37 Photos: Donald Trump's rise Trump is joined by his family as he is sworn in as President on January 20. Hide Caption 37 of 37

Leader of the birthers

For much of President Obama's presidency ,Trump has led the so-called "birther" movement, alleging, in ridiculous defiance of all evidence, that Obama was born outside the U.S. and may not be a real American citizen. This campaign, which he pursued long after others dropped it, was clearly an attempt to turn the first African-American president into a foreign "other" and thus, presumably, render him illegitimate.

When the comedian Jon Stewart went after him on his satirical nightly broadcast, Trump reached once again for an argument based on ethnicity. He tweeted : "If Jon Stewart is so above it all & legit, why did he change his name from Jonathan Leibowitz. He should be proud of his heritage!" This from a German-American man who had posed as Swedish.

Trump started off his run for the presidency a year ago with a bigoted rant about undocumented Mexicans, braying about how "they're bring drugs, they're bringing crime. They're rapists." The effect of this talk was to ramp up public anxieties about people who are actually less likely to commit crimes than others. A pair of Massachusetts men were arrested for beating a Latino person they encountered on the street and, according to police, said, "Donald Trump was right."

Next Trump retweeted false "data" alleging that black assailants account for more than 80% of white deaths due to homicide. The numbers were too high by a factor of five. And don't forget Donald Trump's attitudes about the 1.5 billion Muslims of this world. Those who are abroad would be temporarily barred from our shores, on account of their religious faith, by a President Trump.

Dividing and demonizing Americans

Now we have Trump's ethnic-based bashing of Gonzalo Curiel, which began with the suggestion that the judge, who was born in Indiana, was a Mexican man who somehow managed to become a federal judge.

When Trump appeared Thursday at a rally in San Jose, a peaceful protest outside turned violent. Eggs and bottles were thrown at Trump supporters and police made arrests. Some protesters waved Mexican flags. The words "Go back to Mexico," were shouted.

The beating in Massachusetts; the violence in San Jose; this is what comes from Trump's repeated effort to demonize others and pit one group of Americans against another.

Although his divisive view has gained more notice of late, it is not new. Indeed, it is a deeply felt belief that he has passed on to the younger generation of Trumps. His eldest son Donald Jr. told me that, "Like him [Donald Sr.], I'm a big believer in race-horse theory. He's an incredibly accomplished guy, my mother's incredibly accomplished, she's an Olympian, so I'd like to believe genetically I'm predisposed to better-than-average."

In Trump's world, comments about a person's ethnic and racial background are fair game. And yet he says , "I am the least racist person you have ever met."

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Trump's kind of thinking was common in the 1950s, when he was a boy. This is the period evoked when he says he wants to "Make America Great Again." In fact, the 1950s were marred in many ways, including by the stereotypes people clung to about group identity.

Thankfully, most Americans grew beyond this type of thinking and learned to consider people as individuals and view character as paramount. What's most worrying about Trump is the evidence that he has not joined the rest of us.