I am fascinated by Stephen Miller.

He is the 30-year-old wunderkind political adviser in the campaign of Donald J. Trump whose job has been to whip up the crowd prior to Trump taking the stage.

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Miller’s powerful lines, the ones that really froth the mob, all revolve around immigration. To stoke the emotions, he repeatedly references the brutal murder of Kate Steinle at the hands of an illegal immigrant.

“How many children are dead because of our sanctuary cities?” he asks. “Don’t ever, ever let anyone tell you that you’re not a good person because you want to secure the border!”

And then, playing John the Baptist to Jesus, Miller says, “I have some good news for you, folks, I have some fabulous news.” And he brings on, that’s right, Donald the Savior.

According to a long profile of Miller by Julia Ioffe in Politico, Miller is fast becoming the forward face of the Trump campaign. His former boss, Alabama Sen. Jeff Sessions, said he can’t think of anyone as valuable to a presidential campaign since Karl Rove. When Trump brought Miller on board, Ann Coulter, America’s blondest race-baiter, tweeted, “I’m in heaven!”

But what stopped me short in Ioffe’s report was this biographical tidbit: Stephen Miller grew up in Santa Monica, in a Jewish family.

Cue the record scratch. What? I doubted the Family Miller came over on the Mayflower, and I was positive they weren’t here to greet the boat. Could it be this young anti-immigrant leader is the descendent of immigrants? With the help of attorney and genealogy whiz E. Randol Schoenberg, I had my answer. On his mother’s side, Miller is a Glosser — and you could write a book on the Glossers. In fact, someone did.

For $19.99, I bought the Kindle edition of “Long Live Glossers” by Robert Jeschonek, a history of Pennsylvania’s first family of retail.

“Imagine living in a place where armed Cossacks ride through the streets, looking to cripple or kill you,” Chapter 3 begins.

And so it was Wolf Lieb Glotzer and his wife, Bessie, sought to flee “dreary, scary” Antopol, in Belarus. On Jan. 7, 1903, Wolf arrived in New York aboard the German ship S.S. Motke with $8 in his pocket. He was eventually joined by his son, Natan, a tailor, and his brother Moses, who had arrived earlier, having escaped conscription in the czar’s army. On a visit to Uncle Moses, Natan stopped in Johnstown, Pa., and fell in love with the place. He found work as a tailor and soon bought the shop.

You know the rest. Glossers expanded. More family, including brother Sam, joined in, and Glosser Bros. eventually grew into a chain of dozens of stores, becoming a beloved part of the community before eventually closing. And so it was: Sam Glosser begat Isadore, whose grandson is, yes, Stephen Miller.

By becoming Trump’s anti-immigrant avatar, Miller demonstrates that in America, truly anything is possible: The great-grandson of a desperate refugee can grow up to shill for the demagogue bent on keeping desperate refugees like his great-grandfather out.

But it’s different now, you say. Miller’s forebears came here legally, and Trump is not about stopping legal immigration.

Well, false. Last week at a rally in Portland, Maine, Trump attacked legal immigration from countries that are “prone to terrorism,” including Somalia, Morocco. Uzbekistan, the Philippines, Pakistan, Yemen, Syria and Afghanistan.

“We’re letting people come in from terrorist nations that shouldn’t be allowed because you can’t vet them,” Trump said, according to The Washington Post. He warned the crowd of “outsiders pouring into our country.”

(How a Trump administration will handle immigration from Israel, where far more terrorist acts are committed than in Morocco, is anyone’s guess.)

And for Miller to say his family came to America “legally” is simply a ruse. There was no illegal immigration at the turn of the century, because all non-Asian immigration was essentially legal until the 1920s.

Then, as now, angry voices fought to keep these immigrants out. They organized the Immigration Restriction League, focused on shutting the ports to swarthy Italians and Jews.

“The floodgates are open,” wrote one anti-immigrant newspaper editor as the Eastern European Jews docked in New York. “The horde of $9.60 steerage slime is being siphoned upon us from Continental mud tanks.”

Such sentiments led to the Immigration Quota Act of 1924 — which effectively shut the door to Jewish immigration on the eve of the Holocaust.

Miller’s stump speech taps into that same, ever-present strain in the American body politic. But when an American Jew turns on immigrants, there is a whiff of head-scratching hypocrisy, if not something more clinical. It is taking the side of people who, in a historical blink of the eye, would have met your own great-grandparents at the docks with stones and spitballs.

It is taking a fixable problem like immigration reform and making it intractable by stoking anti-immigrant fear and hate, by calling for a ban on an entire religion, by demeaning the sons and daughters of immigrants by race — all things Miller and his boss are doing. The goal of that behavior isn’t to fix a broken system, but to score political points off it.

So Miller will scream the name of Kate Steinle’s murderer but never mention, say, Antonio Diaz Chacon — an illegal immigrant who, in 2011, chased down and tackled a child molester who had just abducted a 6-year-old girl.

Most immigrants, illegal or not, come to America to live secure, prosperous lives. Most are no different than Natan and Sam Glosser.

Thank God the anti-immigrant demagogues of 1900 didn’t get their way. The Glosser brothers would have been left to molder in some Belorusian shtetl, where fate would have given them the choice of Hitler or Stalin. And Stephen Miller would never have been born.

But he was. He had the blessing of being born the great-grandson of Jewish immigrants, and not the child of today’s refugees, who only want the same chance Sam Glosser once had to make themselves, and America, great.

ROB ESHMAN is publisher and editor-in-chief of TRIBE Media Corp./Jewish Journal. Email him at [email protected] You can follow him on Instagram and Twitter @foodaism and @RobEshman.