Barack Obama's planned visit to his "ancestral village" in Ireland reminds us that Irish genealogy has long been an inexact science.
As Irish as cabbage
Irish genealogy has always been an inexact science: witness the appearance over the years, in the emerald green football jerseys of the Republic, of such obvious Irishmen as Andy Townsend (born and brought up in Kent, south-east England), Mick McCarthy (still speaks in the gruff tones of Barnsley, Yorkshire) and Ray Houghton (impenetrable Glasgow accent incomprehensible outside the west of Scotland).
Indeed, the Irish once appointed as head coach the former Northumberland coal miner and England 1966 World Cup winner Jack Charlton, apparently on the basis that he once went fly-fishing in Connemara.
It is therefore no surprise that when Barack Obama arrives today - weather permitting - in Moneygall, Co Offaly (pop 300), it will be to visit what the Irish insist has been his ancestral home since the year 1698.
The president's welcome to Ireland's family tree has been effusive. His eighth cousin, Moneygall resident Henry Healy, has been nicknamed Henry VIII; family resemblances have been detected ("Henry has Obama's ears"); and a song by the Corrigan Brothers is ever-present on the airwaves ("He's as Irish as bacon and cabbage and stew, He's Hawaiian and Kenyan-American too; O'Leary, O'Reilly, O'Hare and O'Hara, There's no one as Irish as Barack O'Bama").
A cloud, however, has appeared on the horizon. In neighbouring Co Tipperary, it is being claimed that the president's real closest living relatives are residents of the village of Ballygurteen. An unseemly genealogical squabble looms. To settle it, perhaps Mr Obama might be persuaded to bring along his celebrated birth certificate.