Jane Buckingham, a 52-year-old Beverly Hills marketing executive and author of the “Modern Girl’s Guide to Life” book series, always told her two kids, Jack and Lilia, that “they’d end up fine, that she didn’t care if they went on to make money. As long as they were kind, that would make her happy as a mom.”

But when academic consultant William “Rick” Singer, 59, told her that Jack’s 3.4 GPA and ACT score in the 94th percentile “weren’t good enough,” she gave $50,000 to Singer’s “charity” to have somebody else take the ACT for her son, earning a just-slightly-better score than he did on his own.

“She knew this was cheating, even if she wasn’t picturing a federal crime,” write co-authors Melissa Korn and Jennifer Levitz in “Unacceptable: Privilege, Deceit & the Making of the College Admissions Scandal” (Portfolio), out now.

“It also seemed like checking a box to solve a problem. Singer was going to help make this better. She knew it was wrong but not that wrong, right?”

Even though her son had made it clear he would be happy at almost any college, Buckingham worried she wasn’t doing enough.

“I needed to make myself feel like a better mother,” Buckingham explained in a letter to the judge in her trial. (She was convicted in October 2019 of conspiracy to commit fraud and sentenced to three weeks in prison, which she served last year.)

Jack, who had no knowledge of what his mother had done, first learned of the admissions scandal on Twitter. A legal document with a list of defendants was posted to the site, and Jack was stunned to see his mom’s name on it.

“What’s going to happen now, Dad?” he asked before collapsing into his father’s arms.

The college admission scandal, dubbed Operation Varsity Blues, exposed just how far American parents would go to get their kids into a brand-name college. In a conspiracy that lasted between 2011 to early 2019, parents from California to New York allegedly bribed coaches and paid for forged standardized tests to get their kids into elite schools like Yale, Stanford, Georgetown and the University of Southern California.

Even celebrities were touched by the scandal: “Full House” actress Lori Loughlin, 55, and her fashion-designer husband Mossimo Giannulli, 57, paid $500,000 in bribes to get their two daughters into the University of Southern California with fake athletic profiles. Felicity Huffman, the 57-year-old actress from TV shows like “Desperate Housewives” and a mother of two, paid $15,000 to Singer to have her daughter’s SAT scores secretly corrected in 2017.

Singer, the mastermind accused of taking $25 million in bribes from parents, exploited their worst fears to fuel his scheme.

As Huffman explained in a 1,400-word letter to Massachusetts federal Judge Indira Talwani in September 2019, her bad decisions stemmed from years of parenting anxiety.

“I find motherhood bewildering,” she wrote. “I so desperately wanted to do it right and was so deathly afraid of doing it wrong.”

Parents like Huffman are hardly exceptions, regardless of economic means. A study published last summer in Clinical Psychological Science found that an estimated 3.5 million people in the US suffer from parental burnout, which can lead to poor decision-making: “If you want to do the right thing too much, you can end up doing the wrong thing,” Moïra Mikolajczak, the study’s lead author, explained in a statement.

“One striking part of this story is that we can see ourselves in some of these parents,” Korn, the book’s co-author, tells The Post. “We don’t want to be like them, but there is a relatable element to the mom or dad who pushes too hard, or who’s a little too insecure, or who desperately wants to help their child avoid disappointment.”

Singer didn’t have an academic past that resembled anything he promised his clients.

Raised by his divorced mother in Lincolnwood, a North Side suburb of Chicago, it took Singer eight years to get a college degree, transferring from a public junior college in Dallas to a Catholic university in San Antonio to the non-denominational Trinity University, where he graduated in 1986 with degrees in English and physical education.

He crisscrossed the country in the ’80s, coaching softball and basketball at high schools and colleges from Omaha to Sacramento. Even then, he showed a proclivity for bending the rules. While coaching a JCC middle-school basketball team in Omaha, Singer “brought in a tall student suspected by other players to be a ringer from a local Catholic prep school,” write Korn and Levitz.

In 1992 he launched Future Stars, a consulting firm for student-athletes, which evolved into the CollegeSource LLC in 2002, where he worked with students (not just athletes) from small, private high schools without in-house college counselors. For $1,200 per hour, he shared his expertise from years of working behind the scenes at colleges nationwide.

His timing was fortuitous. During the late ’90s and into the next century, the children of baby boomers were “graduating from high school in droves, ratcheting up competition for spots at elite and even formerly middling schools,” write Korn and Levitz.

Ranking colleges, which US News and World Report began doing annually in 1987, became a cottage industry, rating everything from majors to party atmosphere. It was no longer enough for a student to get into college, it had to be the right college.

“Parents seemed dumbfounded at how dramatically unpredictable it had all gotten since they went to school,” write Korn and Levitz. Colleges once considered “safety schools” were now out of reach. Parents would exclaim to counselors, “My kid needs a 3.6 to get into CU Boulder? Are you kidding me?”

USC, once mocked as “University of Spoiled Children,” transformed its academic reputation in the ’90s — luring more esteemed faculty and exceptionally gifted students — and went from accepting 75 percent of applicants in 1987 to just 23 percent in 2011.

Parental anxiety about college was mostly their own doing. There were plenty of great colleges with higher acceptance rates, like Virginia Tech, which took in 72 percent of applicants in 2014. But parents bought into the idea “that only a certain small list of selective schools were worth going to,” Korn and Levitz write.

Singer connected with wealthy parents by speaking at college prep events across the country, and relying on the word of mouth of happy clients.

Singer’s strategy for getting his clients into elite colleges came down to a simple concept: “The side door.”

When you have done everything for your kid their whole life, you have no faith in their ability to do anything on their own.

 - Tara Dowling, on how parents fell for Singer’s scheme

As he explained during his court testimonial: “There is a front door of getting in, where a student just does it on their own. And then there’s a back door, where people go to institutional advancement and make large donations, but they’re not guaranteed in. And then I created a side door that guaranteed families to get in.”

At least in the beginning, Singer’s side-door approach wasn’t technically illegal. He knew, for instance, that the diagnosis of a learning disability was easy to get for a student and could lead to getting extra time during college-entrance exams.

It wasn’t until 2008, according to an FBI affidavit on Singer, that his methods crossed the line into criminality.

It was around this time that Singer created a charity, Key Worldwide Foundation, allegedly devoted to helping disadvantaged kids. But it was just a vehicle to accept bribes from parents. They gave anywhere from $15,000 to $200,000 (or more) as a tax-exempt donation, which would be distributed to coaches, test proctors and others involved in making sure their children had opportunities that others didn’t.

This wasn’t the version Singer sold to parents. “He gave the impression of having a sophisticated insider’s awareness of the culture of admissions,” the authors write. “He convinced people that he knew legitimate ways, even if they involved some truth-bending, to work the system.”

Singer was a salesman like something out of “The Music Man,” his personality “a brew of charm and manipulation,” write Korn and Levitz. He excelled in riding the line between telling parents what they wanted to hear — “Yes, your kid can do this. Don’t pay attention to what the high-school counselor says” — and their fears — “Your kid doesn’t have the grades to do this without me.”

Parents ran the gamut from those who didn’t care that they were breaking the law — one mother, after learning that her donation to Singer’s charity for helping her son cheat on his ACT was a tax write-off, exclaimed, “Oh, even better!” — to those who had given up hope.

“I just lost confidence,” says Stephen Semprevivo, a Los Angeles business executive who hired Singer in 2016 to help his son Adam get into Georgetown University. “I lost confidence in Adam. I let Singer make me feel that Adam couldn’t do it.”

Semprevivo was found guilty of paying $400,000 to Singer’s charity, which was used to bribe a Georgetown tennis coach and get Adam accepted into the school as a tennis recruit, a sport he rarely played.

Felicity Huffman sought out Singer in 2016 on the recommendation of other parents. Although on her parenting blog, What The Flicka, she often advised her readers to let children stumble and make mistakes, she was swayed by Singer’s grim outlook of her eldest daughter Sophia’s chances of getting into a performing-arts college.

Sophia, now 19, needed to boost her SAT score to at least 1250 or ideally 1350 to have a shot, Singer told her. “He may not have known much about performing arts programs,” writes Korn and Levitz. “Or he may have simply been building up to his illegal proposal by setting the bar unnecessarily high.”

If Huffman had looked elsewhere, she would have found plenty of evidence that Singer was wrong. Several of Sophia’s classmates were accepted to the same colleges on Sophia’s wish list with SAT scores in the 1100s. But Huffman “had come to rely too heavily on Singer as a main source of guidance,” the authors write.

In October of 2017, Huffman learned that the College Board had approved a request by Sophia’s neuropsychologist to get extra time on the SAT because of her learning disability. But Singer suggested an extra safeguard; Sophia would take the test in a special location, where a proctor would “correct” any of the answers she got wrong.

In a phone call between Huffman and Singer, recorded by the FBI, Singer asked if she understood that the proctor would “take [the test] with [her daughter] and for her.” Huffman responded, “Yes.”

Huffman donated to Singer’s charity, convincing herself “she was just giving her daughter a fair shot so that, as Singer explained it, the girl could focus on her grades … and not worry about the test,” Korn and Levitz write.

Since the federal investigation into the scandal began, 53 people (as of this writing) have been charged with conspiracy to commit wire and/or mail fraud, 25 have pleaded guilty, and Singer, who still awaits a trial, is facing a maximum of 65 years in prison. Huffman served 11 days of a two-week sentence at a federal prison in Dublin, Calif., and was released last October. Loughlin and Giannulli, who pleaded guilty in May, face between two and five months in prison, a $250,000 fine and 250 hours of community service.

In the wake of the scandal, some colleges have tried to make adjustments. Yale plans to randomly audit the records and extracurricular accomplishments of incoming students, and Stanford and Dartmouth (the latter wasn’t named in the criminal case) will now be flagging the athletic credentials of possible recruits.

But the biggest changes most likely need to come from parents themselves.

Tara Dowling, who’s been counseling at private prep schools since the early ’90s, told the authors that she’s seen a rise in parents losing trust in their own children. “When you have done everything for your kid their whole life, you have no faith in their ability to do anything on their own,” she says.

“Americans systematically weakened their children in the 1990s and the early 2000s,” adds Jonathan Haidt, an NYU professor and co-author of the book “The Coddling of the American Mind: How Good Intentions and Bad Ideas are Setting Up a Generation for Failure.”

“Children do not become strong if they are protected from setbacks, teasing, exclusion and conflicts.”

This growing instinct to coddle children isn’t just an issue among rich parents. While Singer gained a reputation for “catering to wealthy, high-maintenance clients,” he also worked “with professional and middle-class families.”

That included Bel Air, Calif., businessman Devin Sloane, whose son Matteo didn’t even want to attend an elite and exclusive college.

“I didn’t care about that at all,” Matteo told the authors. “I just wanted to go to a good school where I fit in.”

But his father, who ran a company that invested in water recycling and treatment systems, wanted to give him more guidance and support than he had growing up. While Matteo had strong grades and test scores, Singer convinced Devin that “his son needed to be even more interesting.”

So Devin agreed to take photos of Matteo in their swimming pool wearing water polo gear, even though he’d never played the sport competitively. Devin didn’t ask questions, as they had the “type of relationship where if dad asked, Matteo followed orders,” the authors write.

The photos were sent to a graphic designer, who transformed them into “action shots.” Matteo was admitted to USC as a water polo recruit, and his father paid $200,000 to Singer’s charity.

Matteo learned of the scheme while home for spring break during his freshman year at USC. When his father returned home after posting bail, his son was waiting in the kitchen of their Bel Air home to confront him.

Matteo asked: “Why didn’t you believe in me?”

“I never stopped believing in you, not even for one second,” Devin told his son. “I lost sight of what was right.”

Devin was sentenced to four months in prison and a $95,000 fine, and Matteo, who is planning to return for his third year as a student at USC, declined to reveal whether the university has disciplined him.