DUBLIN - He downed a pint of Guinness with a distant cousin and checked out centuries-old parish records tracing his family to Ireland. From the tiny village of Moneygall to a huge, cheering crowd in Dublin, President Barack Obama opened his four-nation trip through Europe on Monday with an unlikely homecoming far removed from the grinding politics of Washington and the world.

"My name is Barack Obama, of the Moneygall Obamas, and I've come home to find the apostrophe we lost somewhere along the way," a clearly tickled Obama - make that O'Bama - told the overflow throng at Dublin's College Green with his wife, Michelle, right by him. "We feel very much at home."

Obama's feel-good indulgence in Ireland came at the start of a four-country, six-day trip that is bound to get into stickier matters as he goes. The only hitch on day one was the threat of a volcanic ash cloud from Iceland that led the president to leave Ireland without even a night's stay and land in England on Monday night.

His high point in Ireland was a helicopter jaunt to Moneygall, population 350 or so, where the president's great-great-great grandfather, Falmouth Kearney, was born and where thousands congregated to welcome the United States' first black president home. Obama met there with his nearest Irish relative, 26-year-old accountant Henry Healy, and they stopped in at Ollie's Bar for a Guinness.

It was a moment and a pint to savor. To the approval of the pub crowd and people all across Ireland watching on television, Obama downed the full pint in four slurps and came away with a foam mustache.

"The president actually killed his pint! He gets my vote," said Christy O'Sullivan, an Irish government clerical worker taking a long lunch break to watch TV footage of Obama's visit. "He's the first president I've actually seen drink the black stuff like he's not ashamed of something."

Michelle Obama, for her part, drank her full half-pint and then got behind the bar herself to serve Moneygall's parish priest, the Rev. Joe Kennedy.

An Irish link is good news for any American politician trying to connect with voters, and particularly for one who's been dogged by questions about whether he was even born in the United States. By some estimates, 35-40 million Americans trace their ancestry to Ireland. While Ireland, population 4.5 million, is a relatively small player on the world stage, this nation roughly the size of West Virginia has been a popular stopping point for modern American presidents ever since John F. Kennedy came in 1963.

It wasn't until the 2008 presidential campaign that Obama discovered he had Irish roots, when a priest of the local Anglican church, Canon Stephen Neill, located the family's baptismal records and established the connection. Falmouth Kearney, who immigrated to the United States in 1850 at the age of 19, is a great-grandfather of Obama on his Kansas-born mother's side. His father was born in Kenya.