Today, a Kennedy might have a chance at the White House in the 21st century if he or she remembers the lessons from the family's history and can reinvent them for a new America -- one that the Kennedy family helped to create.
The key to the family's political future depends on understanding its true past rather than some romantic notion.
Like Trump, JFK was a wealthy outsider
While the Kennedy legacy is often presented as TV comfort food -- beautiful images of "America's royalty" scored to the soundtrack of "Camelot" -- it's important to remember that John Fitzgerald Kennedy was the first US president from a minority background. He was an Irish Catholic from Massachusetts, long ruled by white Anglo-Saxon Protestants who looked askance at anyone connected to the Pope.
During the 1960 election, Kennedy faced a startling amount of anti-Catholic bigotry. From today's perspective, it's hard to imagine what a challenge Kennedy's candidacy posed to the existing WASP establishment.
The weekend before the nation went to the polls in November 1960, The New York Times editorial board concluded that "Mr. Kennedy's Catholic religion is perhaps the greatest imponderable in the campaign."
"Millions of votes are certain to be cast for and against the Democratic candidate because of his church," it wrote.
For many Americans, Kennedy's campaign was a truly aspirational breakthrough -- allowing others from a diverse background to dream of becoming president. In the decades that followed, the candidacies of Barack Obama, Hillary Clinton, and Mitt Romney (a Mormon) -- all from different minority backgrounds of their own -- were compared to JFK's pioneering example.
That underlines an important lesson: The Kennedys have always done well as outsiders, rather than products of entitlement or privilege. That seemed hard to do for Harvard-trained JFK, the son of one of America's richest men.
And surely it would be more difficult for a future Kennedy, the scion of family trust funds and winter compounds in the Florida sun.
Influenced by immigrant roots
Being a political "outsider" is more a matter of perception than of money, as billionaire Donald Trump demonstrated in 2016.
Both JFK's 1960 election -- as well as Robert Kennedy's 1968 primary campaign (until it was abruptly ended by his assassination) -- attracted numerous different "outsider" groups who felt long excluded from existing power.
The message of these Kennedys resonated with a big tent of various constituencies. They ranged from union coal mine workers in West Virginia to immigrant farm workers in California to blacks in urban neighborhoods to second-generation children of Irish, Italian, Jewish and other white ethnic groups moving to America's emerging suburbs.
Despite their own wealth, JFK and his family understood in their bones the hardscrabble hopes of their working-class supporters. The diaries, letters and private notes of the Kennedys reveal how much their Irish Catholic immigrant background informed their public and private lives, far more so than the Camelot royalty myth perpetuated by the media.
One of the most lasting examples is how JFK's little-known book, "A Nation of Immigrants," inspired his 1963 legislative proposal that eventually became the 1965 Immigration Act. This law opened the door to millions of newcomers and dramatically redefined the America in which we now live.
A future Kennedy would be wise to claim this powerful part of the family's legacy by reaching out to Latino and Asian-American voters. While immigration can surely be a contentious, sometimes volatile issue -- just like it was in the 1840s when Irish arrived in waves -- a new Kennedy candidacy might stress how that 1965 law embodied some of the most enduring values of American life, such as opportunity, freedom of religion, and the idea of family unification.
A moderate liberal
At the same time, a new Kennedy candidacy would do well to remember some of the more conservative aspects of JFK's 1960 campaign -- the traditional values of tight-knit immigrant families, ones that might still appeal to suburban Catholics who in recent years revered Ronald Reagan more than any Democrat.
Repeatedly in 1960, JFK invoked the lessons he learned from Winston Churchill in facing down dictators and about the need for American resolve as a bastion of international freedom. Both Churchill and Kennedy revered courage. In his Pulitzer Prize-winning book, "Profiles in Courage," JFK began with, "This is a book about the most admirable of human virtues --courage."
Instead of being defined in the public's mind by tragedy and sex scandals, a new Kennedy might remind this generation how past family members sacrificed their lives in both war and public service.
History shows JFK was a moderate liberal, certainly not a leftist. At the Berlin Wall and elsewhere, he stood up strongly against Communists and other despots. He didn't appease or make excuses for them.
Given President Trump's dalliance with Russian leader Vladimir Putin, a Kennedy-like Democrat might recall how former Communists like Putin deliberately put America's defenses at risk during the last Cold War and brought the world to the brink of nuclear catastrophe. While reaffirming the Democrats' traditional support for Social Security and programs for the sick, aged and poor, such a Kennedy candidacy today might underline the need for vibrant but well-regulated capitalism rather than a creeping form of socialism.
It's also important to remember that the Kennedys of old strongly supported unions -- and all the bargaining power that meant for low-income workers seeking livable wages and good health coverage for their families. Recent Democrats seemed more intent on embracing Wall Street donations than solidarity with the Teamsters.
In a world where factory machinists and truck drivers may be soon replaced by machines powered by artificial intelligence, will a new Kennedy speak out, loudly and from the gut, for these lost workers?
Unlike some Democrats, a future Kennedy campaign might embrace religious values rather than shun them. While JFK was forced in 1960 to address our nation's traditional separation of church and state, a future Kennedy could echo Pope Francis, a worldwide advocate for social justice.
Conservative critics have often used sex, abortion and the church's more conservative teachings to lambaste liberal Kennedys and paint them as secularists. But drawing upon the past, a new Kennedy might remind these critics, as well as fellow liberals, that some of the most progressive measures of the 20th century -- such as the civil rights reforms of the Rev. Martin Luther King Jr. -- had deeply spiritual roots.
Overcoming the 'Camelot myth'
Perhaps the most important lesson for this current Kennedy generation is also an intangible: avoiding the appearance of entitlement. Family members like Massachusetts Rep. Joe Kennedy III, who recently gave the Democratic Party's televised response to President Trump's State of the Union speech, must carefully steer clear of any hint of inevitability, that somehow the marquee value of the Kennedy name entitles you to lead.
Too many family members already have stumbled on that one. Call it the curse of the Camelot myth.
Another hurdle would be American voters' current disdain for political dynasties, as evidenced by the 2016 presidential campaign, in which both Jeb Bush and Hillary Clinton failed to capitalize on their presidential relationships.
Political dynasties aren't unheard of in the United States: Most recently, Americans voted in father-son President Bushes in 1988 and 2000. But before that, you have to go back to the early 20th century to the Roosevelts (distant cousins Teddy and Franklin) and then, even farther back to father and son John and John Quincy Adams.
Without doubt, the key to political success depends on whether a Kennedy presidential bid is perceived as a fresh breakthrough, like JFK's candidacy that touched millions, or merely as a caretaker of the political establishment, manipulating voters with hoary images of the past.
Such a new and compelling message seems like a tall order. But it's not impossible.