When it comes to his sister, Curtis Ingraham doesn’t exactly hold back.

Conservative political commentator Laura Ingraham speaks during the third day of the Republican National Convention in Cleveland in July 2016. (AP Photo/Mark J. Terrill, File)

Over the past year or so, Ingraham has won a reputation — and a significant Twitter following — for attacks on his high-profile sister, Fox News host Laura Ingraham. At different times and on a wide variety of platforms, he has called his sibling “a monster,” “a Nazi sympathizer” and a “racist.”

But after the controversial pundit compared Greta Thunberg and other youth climate activists to Stephen King’s “Children of the Corn” on Monday night, Curtis Ingraham took things to the next level.

“Clearly my sister’s paycheck is more important than the world her three adopted kids will inherit,” he wrote on Twitter in a post that had garnered roughly 60,000 likes — and climbing — as of Tuesday morning. “I can no longer apologize for a sibling who I no longer recognize.”

Experts in political discourse said Curtis Ingraham’s decision to invoke his sister’s children marks an escalation in their ongoing feud. Children have typically been viewed as an out-of-bounds subject in American public debate, although that norm has eroded over the past several years, according to University of New Hampshire professor Lawrence J. Prelli.

“He’s definitely making it more personal,” Prelli said. “But I have to say, it’s ironic to be parsing out how this could be mean to Laura Ingraham. . . . What about her framing this girl as demented?”

Curtis Ingraham could not immediately be reached for comment, and Fox News did not respond to a request for comment.

Stephen King’s 1977 short story “Children of the Corn” — later made into a popular movie — focuses on a murderous gang of children who live in cornfields in rural Nebraska, dress in Amish-style clothing and worship a vengeful deity called “He Who Walks Behind the Rows.” Their god demands they murder all adults in the town.

During the Sept. 23 edition of her show, “The Ingraham Angle,” Laura Ingraham drew a parallel between the fictional cornfield cult and the young people leading a global movement to combat climate change. Her remarks came on the same day that Greta Thunberg, the 16-year-old from Sweden who has become the face of climate advocacy, delivered an impassioned address before the United Nations urging leaders around the world to take action.

“The adults who’ve brainwashed these kids should be brought up on charges of child abuse,” Laura Ingraham said, speaking before a graphic bearing Thunberg’s face and the words, “The Climatology Cult.”

She later played a clip of Thunberg speaking at the United Nations, followed by an excerpt from the movie version of Stephen King’s novel. In the excerpt, a child cult leader paces past cornstalks, fingering a weapon, and declares: “A time of tribulation has come! A test is at hand, the final test.”

“Does anyone else find that chilling?” Laura Ingraham asked, before concluding: “I can’t wait for Stephen King’s sequel, ‘Children of the Climate.’”

Her comments spurred immediate backlash on Twitter. And she was not the only Fox pundit to draw fire for opining on the teenage climate activist: The network was forced to apologize to Thunberg on Tuesday after Michael Knowles, a guest on its show, “The Story,” called her “mentally ill.” Thunberg, who was diagnosed with Asperger’s syndrome years ago, has called her condition “a gift,” saying it inspired her advocacy.

If anyone broke the “constraint upon criticizing children, generally,” Prelli said, it was Laura Ingraham — not her brother.

“That’s a pretty naked and ad hominem attack, to be characterizing this girl as somehow demented or evil,” Prelli said of Laura Ingraham’s remarks. By contrast, Curtis Ingraham “is not criticizing her children,” he said. “He’s referring to them as children who have a future who can be impacted by climate change — I don’t see how that’s at all out of bounds.”

Curtis Ingraham — a teacher who lives in Northern California, according to the Daily Beast — began speaking out about his sister in early 2018, at the time tweeting to an audience of several hundred. His commentary swiftly earned him fans: Today, his followers number more than 21,000.

The siblings have long had a complicated relationship, the Daily Beast reported. They hold sharply different political views — a divide exacerbated by the fact that Curtis Ingraham is gay. Although they were close at an earlier period of their lives, the two have “very limited contact at this point,” he told the Daily Beast in a 2018 interview.

He added that his sister’s prominent role as a right-wing analyst on Fox News — Laura earned her own prime-time show in September 2017 — all but destroyed their ties. Since her show debuted, Laura Ingraham has been accused of racism, anti-Semitism and of promoting white supremacy. The network has vehemently defended her every time.

“It is not easy for me,” Curtis Ingraham told the Daily Beast. “My heart has been bruised; it has been kind of irreparably bruised. But I’m trying to illuminate and shed a light on hypocrisy.”

It’s not the only social-media-fueled division between family members to garner headlines in the Trump era. White House adviser Kellyanne Conway’s husband, lawyer George Conway, has earned a massive Twitter following as a devastating critic of President Trump — his wife’s boss.