Steve Jobs' ill-health resignation as CEO of Apple is sadder news still for those of us who love the iPhone, iPod, iPad, MacBook - and being on the same side as the world's coolest company. But St Steve's decision also helps us ask what has driven the amazing, super-charged career of a university drop-out. What's the secret?
Perhaps Barack Obama has the answer: the fact is that neither of America's two most famous men knew their fathers. Jobs was adopted as a baby, and Obama was brought up by his maternal grandmother. Obama recently explained how he came to feel strong enough to make life and death decisions for an entire country: " I would say the fact that I grew up without a father in the home. What that meant was that I had to learn very early on to figure out what was important and what wasn't, and exercise my own judgement and, in some ways, to raise myself".
In fact, a full 25% of the 44 US presidents have been fatherless including Clinton, Washington and Jefferson. They are part of a long line of fatherless high-achievers including Nelson Mandela, John Lennon, Alan Greenspan, Charlie Chaplin, Lance Armstrong, Quentin Tarantino, Jack Nicholson, Tom Cruise, and Amazon founder Jeff Bezos. (Oh, and Stalin, Hitler and Mao). A 1960s study found that no fewer than 20% of the then notable scientists also did not know their fathers. Coincidence or what?
Research shows that the fatherless (whether men or women) are frequently driven, at least partly by feeling more free to find their own paths in life - for better or worse. They find themselves having to cope with making adult-size decisions from a very pre-adult age.
It is, of course, less than a month since UK Prime Minister David Cameron all but blamed absent fathers for the country's inner-city riots. It happens to be true that fatherless children are statistically much more likely to be violent, to experiment with sex, drugs and drink at an early age, to under-perform at school - and, in their turn, to contribute to the cycle of fatherlessness.
In the UK, there are some 1million under-16s who have no contact with their father. In the US, it is worse and 30% of all children are growing up without their natural fathers. A 2006 study there showed that fatherless young people accounted for 63% of youth suicides, 71% of teenage pregnancies, 90% of homeless and runaway children, and so it goes on.
The successes and the failures among the fatherless are, in fact, recognisably linked. Research shows clearly that, for many of these young people, it makes them more introspective ("no bragging about Dad's occupation in 'show and tell' "), which can affect later relationships as adults. It is easy to see how some can, therefore, be driven to success by a self-centred determination, while others become introverted or uncommunicative - and consumed by anger.
But even behind the success of the fatherless is often a perceptible sadness. Tom Cruise, whose father left when he was 11, said recently: "I had (and have) a desperate need to belong. When I was young, I could not find the courage to make new friends when we moved to Louisville after my father left."
The American author Lisa Carver says her father's decision to leave the family is what drove her to become a writer: "My letters to him were plaintive, made-up descriptions of myself and my world, meant to lure him home. I can imagine many politicians, perhaps including the President, are looking for a long departed father. Instead of writing letters that create imaginary worlds, they write laws that change the real one." Carver is painfully honest about her motivation: "I've had four books published but I don't care about them the second they're completed. I am unsatisfiable. I always need more. That's ambition. That's drive. That's the fatherlessness."
Bill Clinton is similarly reflective: "I think the fact that I was born without a father - and that I spent a lifetime trying to put together a picture of one - had a lot to do with how I turned out. Good and not so good."
Few people are quite so upfront about their feelings. Even the fatherless who claim not to have been scarred by the experience of losing (or never knowing) their fathers sometimes do so self-consciously and unconvincingly. It is difficult not to believe the UK researcher who reported: "Rejection is the defining characteristic of the fatherless generation. Fatherlessness creates an appetite in the soul that demands fulfilment."
Perhaps it is that restless, search for fulfilment (and the need to prove oneself) which has driven the likes of Steve Jobs, Barack Obama, Bill Clinton and Tom Cruise on to success - at the same time as millions of others appear to have found fatherlessness to be a life-limiting, psychological scar.
Some challenge for a world where regular, two-parent marriages only seem to be going one way.