The afterlives of White House children are not always happy ones. John F Kennedy Jr died tragically young in a plane crash, as did Teddy Roosevelt's son, Quentin, in World War One.
FD Roosevelt's five children divorced 14 times between them. Amy Carter was arrested for protesting against the CIA, although she was later acquitted. Patti Davis was the ‘Renegade Reagan', who took her mother's name as a gesture of disgust at her father's politics, smoked pot, married her yoga instructor in a fit of defiance, divorced him six years later and then posed nude for Playboy at the age of 41, before finally returning to the family fold.
In fact, statistics governing the outcome of former presidential children tell a story of extremes. On the one hand, they tend to become unusually high achievers, while on the other they are more like to be divorced, to die prematurely and to struggle with alcoholism.
What makes the difference in outcome is how much time, and how formative were the years, they spent in the White House.
Given that Chelsea Clinton was 12 when she became the First Daughter, and spent the next eight years in that role, not to mention the hard time she seemed to have adjusting to her position, there was every chance she could have succumbed to the latter, grimmer set of stats.
Instead, on the eve of her top-secret wedding to Marc Mezvinsky, the formerly awkward Chelsea has morphed into a confident young woman, glowing with health and vitality, a high-flying investment analyst-turned mature student and low-key but clever media operator.
When Bill Clinton and Al Gore won their first term in office, in 1992, they did what American presidents and vice-presidents do — they brought their families on stage to celebrate. On one side were the three Gore children: pretty, preppy and cheering enthusiastically.
In contrast, Chelsea, sandwiched as usual between her parents, seemed gawky and unsure; chubby and toothy, with wild hair, braces and dreadful dress sense. She managed a half-wave to the crowd, followed by an agonising blush.
Her underwhelming performance led Saturday Night Live to draw scathing comparisons with Gore's daughter Sarah, and one US TV critic satirised her cruelly as ‘the White House Dog'. Chelsea also had to weather the absurd, lurid rumours that Bill was not her father, that he is sterile, that Hillary is a lesbian, and that her parents have never slept together. For a girl launching into the insecurities of adolescence, Clinton's election couldn't have come at a worse time.
But Chelsea's secret weapon has always been the remarkable relationship she has with her parents. Since she was tiny, she has been the glue in their marriage: two ill-suited people held together by their love for a much-wanted child. She is the one pure and uncomplicated relationship of Bill's life and the primary emotional focus of Hillary's.
In 1988, Clinton had decided against running for office, because he felt that Chelsea, then eight, was simply too young to handle the pressure. Once he launched his bid, both Clintons prepared her well for what lay ahead — role-playing at the dinner table in Arkansas the kind of nasty comments and slurs they could all expect.
One of Hillary's priorities as First Lady was to pay a social call on Jackie Kennedy Onassis, then still the doyenne of all things White House, to ask her how best to protect Chelsea from the inevitable stress of her position. Jackie seemingly warned Hillary “not to let adults become Chelsea's handmaidens” and to “be ruthless about keeping the public from the private”.
Consequently, Chelsea was quite simply off limits to reporters. Requests for interviews or comments, no matter how innocuous the topic, were firmly turned down. Even now, Chelsea doesn't speak to reporters. During the 2008 presidential election, during which she loyally canvassed for her mother, Chelsea was asked a question by a nine-year-old Cub reporter, which she brushed off, saying: “I'm sorry, I don't talk to the press and that applies to you, unfortunately. Even though I think you're cute.”
Hillary's determination to protect Chelsea from public exposure was a logical extension of the quite intense, even controlling, way in which she was brought up — Hillary was a classic ‘helicopter mom', hovering anxiously over her child's development, despite her own role as family breadwinner for many years. She steered Chelsea clear of any interest in make-up and clothes, instead concentrating on her intellectual abilities and sense of achievement.
She even taught Chelsea, when she was in sixth grade, the rudiments of stock market investment. And Chelsea rewarded all these efforts. She was a precocious child who turned into a steady, achieving adult, bypassing all teenage indiscretions.
As far as possible, Chelsea was exposed to some version of normality during the White House years: made to tidy her own room and sweep up the popcorn after movie screenings for her friends.
More important, her parents made time for her. Bill tried to breakfast with his daughter every day, and Hillary would routinely pause her own schedule for an hour or so after Chelsea came back from school to catch up with her day. In all of this, Chelsea seemed wonderfully acquiescent and biddable, passing up the temptation to sew any wild oats at all. She has only been seen drunk once in public, and that was after she moved to England, where she was papped staggering out of the Embassy Club in Mayfair, propped up by then boyfriend Ian Klaus.
The irony, of course, is that, for all her model behaviour, and despite her father's best efforts to lay claim to the Kennedy fairy-dust, Chelsea never captured the public imagination the way Caroline or John-John did.
Her exemplary conduct earned her indifference rather than affection, probably because her initial awkwardness soon gave way to something poised and rather formal. There was no appealing vulnerability or openness with Chelsea — the kind of thing that often gets stars such as Princess Diana into trouble, but gets them loved as well.
There were no real dramas in Chelsea's life, even though she weathered one of the greatest scandals in American public life, suffered the public humiliation that being Bill Clinton's daughter brought for a time, and played a pivotal part in the unfolding of the family reconciliation. Through it all, she maintained poise and discretion. The day after Clinton owned up to his relationship with Monica Lewinsky it was Chelsea who seemed to be holding her parents together, walking between them, holding hands with both as they left for Martha's Vineyard. At the time she was 18 and her parents' devoted protection seemed to have paid off in the way she handled that appalling situation.
She was, inside sources said, furious with her father, but resisted the temptation to make a bad situation worse by taking sides. Instead, she kept both parents close, supporting each in their different requirements. She took holiday time out with Hillary and accompanied Bill on his next international tour when Hillary refused to. One White House correspondent said: “And if Bill had one last friend in the world, it would be Chelsea.”
Even the burden of being your father's best friend and your mother's proudest legacy doesn't seem too much for her. Whatever desire for revolt she may have had has been very well sublimated.
At Stanford, her undergraduate thesis was her father's role in the Northern Ireland peace process. Then she followed his footsteps to Oxford. Away from the heat of the American media, this was where Chelsea really started to shake off her gawky teenage self — the neat, good ‘child of her parents' she had been for so long was replaced with a version more sleekly groomed and highly social.
She attended Wimbledon and Elton John's summer ball and 10 years after being dubbed the ‘White House dog’ her metamorphosis caused Vanity Fair magazine to gush that she was “the new John F Kennedy Jr”.
Along the way there have been boyfriends, such as Klaus, fellow Oxford student, a Rhodes scholar with political interests and bouffant hair, with whom Chelsea split in 2005, because they didn't get to spend enough time together. Before that there was Jeremy Kane, a fellow student at Stanford and a White House intern, who was so keenly political it caused Chelsea to wonder what his real interest in her was. But fiance Marc Mezvinsky, an investment banker, could just be a match made in political (and operatic) heaven.
Marc and Chelsea have known each other since they were teenagers. Both went to Stanford, and Marc's mother even ended her political career — she was elected to Congress in 1992 — by voting for Clinton's 1993 Budget, which included a tax increase for the wealthy. Hers was the deciding vote, and this was used against her in the next election cycle.
Meanwhile, Marc's father, Ed Mezvinsky, has had a career even more colourful than Clinton's. Elected to Congress from Iowa, he lost on his third bid for re-election, then moved to Pennsylvania where he tried, and failed, to make it as senator, then attorney general and finally lieutenant governor. By early 2000, Ed's mansion had been raided by the FBI and he was charged with 69 counts of fraud. He argued mental disorder and diminished responsibility, but the court sentenced the former congressman to 80 months in prison. He was released in 2008 but declared bankrupt.
He and Marjorie, who had raised 11 children, most of them adopted from overseas, then divorced. It's not exactly a mirror image of dysfunctional families, but clearly both Marc and Chelsea have experience of weathering scandals.
The wedding, a fast-leaking secret, is expected to take place on Saturday in Upstate New York, with an attendance list of some 400 friends. Chelsea's stipulation, in order to get round the very many donors, advisers, acquaintances and hangers-on among her parent's entourage, is that she should have personally met every one of the guests.
Bill is well on the way to losing the 15lbs Chelsea has requested, and has said he will try his hardest not to cry as he walks his daughter down the aisle. Her mother, when asked which is harder, negotiating peace in the Middle East or planning her daughter's wedding, discreetly said: “I'd probably call it a draw.”
Chelsea may not be ‘America's Princess', but if rumours of an eventual career in politics can be believed, she may just be the best part of Bill Clinton's legacy, and an enduring testimony to her mother's principles of child-rearing.
For the sake of symbolic continuity, both Bill and Hillary should walk her up the aisle, one on either side, just like the old days.