White House senior adviser Stephen Miller has long been one of the driving forces behind President Donald Trump's harshest immigration policies, but he is a descendant of asylum-seekers.

Miller's great-grandparents found refuge in the US after escaping anti-Jewish persecution in Belarus in the early 1900s.

Miller was an aggressive proponent of Trump's migrant family separation policy, and is reportedly working to bring more immigration hardliners into the administration amid a personnel shake-up.

White House senior adviser Stephen Miller has long been one of the driving forces behind President Donald Trump's harshest immigration policies, including the administration's 2018 "zero tolerance" policy, which prosecuted nearly all adult migrants crossing the US-Mexico border and separated them from their children.

Miller, 33, is reportedly in the process of helping orchestrate a government-wide shake-up of top officials in order to bring in more immigration hardliners.

But Miller's family were asylum-seekers. His great-grandparents found refuge in the US in the early 1900s after escaping anti-Jewish persecution in Belarus, according to Vanity Fair. The Glossers settled in Johnstown, Pennsylvania and opened a tailoring business that grew into a department store and large chain, Glosser Bros., that made Miller's family a fortune.

"Imagine living in a place where armed Cossacks ride through the streets, looking to cripple or kill you," Robert Jeschonek wrote in a 2014 book, "Long Live Glosser's," about Miller's mother's family.

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While Miller has controversially advocated for limiting legal immigration to individuals who speak English, his great-grandmother spoke only Yiddish when she arrived in the US. And Miller was quoted openly disparaging refugees in ex-Trump aide Cliff Sims' 2019 book.

"I would be happy if not a single refugee foot ever again touched America's soil," Miller told Sims, according to the book.

A former aide to former Sen. Jeff Sessions, Miller has for years cultivated his right-wing immigration platform.

Raised in a liberal community in Santa Monica, California, Miller attended Hebrew school at a self-described Progressive Reform Synagogue, according to The Jewish Journal. But he grew into an avid conservative as a teenager, drawing attention at Santa Monica High for his contrarian views. High school classmates of Miller's claim he spoke disparagingly toward Spanish-speaking students.

Read more: Trump pushed his administration to re-implement migrant family separations after he banned the policy in an executive order

Later, as an undergraduate at Duke University, Miller was also well known for his controversial appearances on conservative talk radio and cable news. Miller criticized multiculturalism and immigration in one op-ed for a Duke newspaper.

"We must come to the defense of our heritage," Miller wrote in the column, which discussed the international student presence on campus. "And for us, that fight begins right here, on our campus."

While Trump attempted to distance himself last year from his widely condemned policy of separating migrant families — and falsely claimed that Democrats were to blame for the practice — Miller aggressively defended the policy.