The allegations leveled against Kevin Spacey have dredged up disturbing memories about his childhood — as his brother said their father was a “Nazi child rapist” who abused them for years in their “house of horrors home.”

Randall Fowler, 62, a colorful Rod Stewart impersonator, said he was not surprised that Anthony Rapp accused his Oscar-winning brother of trying to seduce him when he was 14, the Sun reported.

Fowler’s agent, Bonnie Soto, told the Sun: “Obviously this is not new news, but as far as this particular guy, Randy doesn’t know anything because Kevin cut himself off when he became Mr. Rich Millionaire.

“We’re not too surprised. And we know that Kevin has been in the closet for a long time,” added Soto, who is writing a book about child sex abuse with Fowler.

The revelations come as Spacey faces a firestorm of criticism after Rapp, 46, accused him of making a sexual advance on him in 1986.

Rapp — best known for his roles in the “Rent” movie and “Star Trek: Discovery” TV series — told BuzzFeed News about the alleged incident at a party while he and Spacey were both acting on Broadway.

Hours after the bombshell report emerged, Spacey, 58, took to Twitter and admitted for the first time that he is gay and issued an apology.

“I have a lot of respect and admiration for Anthony Rapp as an actor,” Spacey wrote. “I’m beyond horrified to hear his story. I honestly do not remember the encounter, it would have been over 30 years ago.

“But if I did behave as he describes, I owe him the sincerest apology for what would have been deeply inappropriate drunken behavior, and I am sorry for the feelings he describes having carried with him all these years.”

Many have accused Spacey of using his sexuality to deflect attention from the sordid accusation, which Fowler described as “disturbing” to the Daily Mail.

Fowler, a limo driver living in Boise, Idaho, said he had been sexually abused by their father, Thomas Geoffrey Fowler — whom they called “The Creature” — and that their mother knew about it.

Their older sister, Julie, also endured beatings before she fled home when she was 18, according to the Daily Mail.

In a 2004 interview with the paper, Fowler described how their ultra-right-wing, perverted dad was a member of the American Nazi Party.

He was so enamored with Adolf Hitler that he even trimmed his mustache to resemble the Fuehrer’s.

Fowler told the Daily Mail that he refused to have children of his own because he feared they would “inherit the sexual predator gene.”

“I grew up in a living hell. There was so much darkness in our home it was beyond belief. It was absolutely miserable,” he said.

“Years later, our mother actually wrote a letter to all three of us, trying to justify what had gone on by saying she was abused as a child and so was our father,” he said.

“Kevin tried to avoid what was going on by wrapping himself in an emotional bubble. He became very sly and smart,” he added. “He was so determined to try to avoid the whippings that he just minded his Ps and Qs until there was nothing inside. He had no feelings.”

Fowler described his younger brother as an “empty vessel” who had never been in a real relationship with anyone.

“Neither of us had a chance growing up with two such damaged parents. I went through three marriages and 40 affairs,” he said in 2004.

The family moved 10 times — from Colorado, where Fowler was born in 1956, to New Jersey, where Spacey was born three years later — before settling in Los Angeles.

The three siblings felt “trapped,” Fowler said, and weren’t allowed to bring friends to their house, where their father, a technical writer, plastered the walls of his office with pornographic images.

Fowler was allowed to join the Boy Scouts briefly, but said his father pulled him out when he discovered that the scoutmaster was Jewish. Spacey was never allowed to join.

At dinnertime, the children were subjected to their father’s lectures about white supremacy — and rants that the Holocaust was a lie and that Jews controlled the banks and the movie industry, according to the Sun.

Fowler said his father began to sexually abuse him when he was 12, ordering him to the master bedroom to teach him about “the birds and the bees.”

“He unbuttoned my pants and started playing with me,” he told the Daily Mail.

The horrified youngster yelled for his mother.

“She came right up and pounded on the door but Dad had locked it and he told me to keep quiet,” he said. “All of a sudden the pounding stopped. Mom had left. I’d never felt so abandoned. Dad started to perform a sex act on me. That was the beginning of my adolescence.”

Spacey tried to “cheer everyone up” with impersonations of celebrities like Johnny Carson — spot-on acts that he still performed decades later.

“I constantly threatened my father that if he ever touched my brother, I’d confront my mother with what was going on and that would destroy the family,” Fowler said.

He once contemplated suicide, even putting a gun barrel into his mouth, but didn’t pull the trigger when he realized that his death would mean his younger brother would have no one to protect him.

A Spacey spokesman told the Daily Mail in 2004: “Kevin’s brother’s claim against his father is a very serious one and has been a difficult personal family matter.

“The family all feel deeply for his situation. Kevin has not experienced any of the distress that his brother describes as he has never been a victim of abuse and can only sympathize with him.”

Spacey’s reps have not returned messages left by The Post.

In 1990, Fowler finally confronted their mom after their father was rushed to a hospital.

“Our mother sat in stony silence,” he recalled.

When their father died on Christmas Eve 1992 at age 68, she told Fowler that he didn’t have to attend the funeral. Spacey then grew closer to their mother as a rift between the brothers widened.

When Julie Fowler died on March 19, 2003, Spacey had her cremated under a false name to maintain her privacy.

Her ashes were divided into two star-shaped boxes with a gold plaque that bore the words “Everything will be fine.”

This article originally appeared in Page Six.