Maximising your vote is a natural motivation, especially for first-term presidents. But I suspect the degree of ancestral nostalgia was decidedly varied.
One could not doubt how deeply moved John F Kennedy was, almost as if he sensed that his family's triumphant return to Wexford in 1963 ranked alongside his actual inauguration in being the culmination of their sometimes murky journey from coffin ship passengers to overcoming the anti-Irish, anti-Catholic prejudice of the US political elite and reaching the summit of power.
Richard Nixon's visit to Timahoe was decidedly less teary-eyed as he visited a hastily erected tombstone that may -- or may not -- have marked the burial place of one of his mother's people.
Kennedy and Nixon were steadfast political foes, but, when thinking of Ireland, they -- like other US presidents with Irish blood from Woodrow Wilson to Ronald Reagan -- saw Ireland as a place their people had fled from to find refuge and liberty in the US.
US President Barack Obama will go through the necessary pieties of feigning a sense of homecoming today -- the birthplace of one of his 32 great-great-great-grandfathers and therefore definite proof that he is, indeed, 3pc Irish.
But what marks him out from previous presidents is that when he thinks of Ireland he does not just see a land of economic or political enslavement.
He is aware of a journey made to Ireland in 1845 by one American citizen who -- while thousands of Irish fled in the opposite direction -- was fleeing from America on a paddle-steamer called the Cambria to seek sanctuary and freedom in Ireland.
Though, of course, when he became Ireland's first asylum seeker in 1845, Frederick Douglass was not officially a US citizen. He was an escaped slave from the American Deep South, who had initially fled to New York, where slavery was banned but slave owners could still turn up and legally recapture fellow human beings who were deemed to be "their property".
Born into slavery in 1818 in Maryland, Douglass broke the law by secretly teaching himself to read, and by the age of 16 was secretly teaching other slaves to read the bible, until a deputation of slave owners violently broke up his hedge school. His owner sent him to have his spirit broken under the lash of the notorious slave-breaker Edward Covey, but Douglass managed to escape and reach New York, where he attended abolitionist meetings. Unexpectedly invited to speak at one, he mesmerised the attendance with his account of life in slavery.
The key to his brilliant oratory was that he had avidly devoured the speeches of a great Irishman, Daniel O'Connell, in which O'Connell passionately argued for Catholic Emancipation in Ireland, the equal right for Catholics to vote and sit in parliament and the repeal of other discriminations.
It's a long way from Kerry to Maryland, but O'Connell became the escaped slave's inspiration, with Douglass incorporating O'Connell's great oratorical techniques -- and O'Connell's beliefs in equality for all men -- as he become a passionate orator in New York and wrote an account of his life as a slave which became such a sensational bestseller in America, that Douglas had to flee New York and seek asylum in Ireland before his 'owner' recaptured him.
Donal O'Kelly's great play, The Cambria, captures the drama of that cross to the sanctuary of Ireland where he was hailed as 'The Black O'Connell' and was befriended and endorsed by his idol O'Connell, whose words had inspired a black man's flight from slavery.
And Obama's mesmerising rhetorical style that inspired his election was directly and consciously copied from Douglass.
Therefore the real connection that Obama has with Ireland is not the 3pc of his ancestral make-up that can be traced to Moneygall, Co Offaly.
It is that Douglass was the inspiration for Obama, and O'Connell was the inspiration for Douglass -- so the oratory that swept Obama to power has a direct link with a great Irish patriot who achieved genuine change not through the cult of violence and secret societies, but openly by inspiring people in democratic mass meetings.
My school teachers were honourable and interesting. Only once did I encounter thuggish ignorance: a temporary relief history teacher obsessed by extreme Gaelic nationalism, who liked to swing his fists and referred to O'Connell as "O'Connell, the Irishman -- if you could call him an Irishman".
To this relief teacher, politicians like O'Connell and Charles Stewart Parnell, who tried democratically to effect change in a non-violent and accountable way, were not true patriots.
True patriots were only people like the Fenian leader John Mitchel, who -- because he had been jailed for Ireland -- could have no aspect of his character questioned. This is despite the fact that after Mitchel escaped to America he exposed himself as a vehement racist, who penned pro-slavery diatribes in his Citizen newspaper.
Not all Fenian leaders were racists who would have gladly seen a free Ireland acquire colonies to rival those of King Leopold II of Belgium.
Ireland has a great tradition of democratic leaders but we mythologise disparate groupings of rebels.
The fact that Obama is only 3pc Irish is a bonus in being able to bypass the usual cliches we feed Irish Americans.
Instead we should remind him that Ireland was once a refuge for his idol, a black asylum seeker named Frederick Douglas who was inspired by the words of Daniel O'Connell.
That is Obama's real link to Ireland.