COLLEVILLE-SUR-MER, FRANCE (AFP) - A Frenchman who spent his whole adult life searching for his American father, a soldier who fought in Europe during World War Two, said he was "bowled over" after coming face-to-face with a previously unknown half-brother on Monday (Sept 24), thanks to a chance DNA breakthrough.

Andre Gantois, now aged 72, was told he was asking for the impossible when he began his search for his dad aged 20 at the American embassy in Paris, knowing only that his late mother had fallen pregnant shortly after the end of the war.

She had revealed the existence of her American lover on her deathbed, when Gantois was 15, but did not share his name or any other details.

"They told me that what I was asking for was like looking for a needle in a haystack," the retired postal worker from the Lorraine region of eastern France told AFP.

Undeterred, Andre continued to research US military and legal documents, but the breakthrough only came when his sister-in-law suggested he approach a popular American DNA company MyHeritage which specialises in family research.

"I didn't expect anything. I'd come to the conclusion that I'd die without knowing my father," he added.

Instead, after sending off a couple of swabs from his mouth, the group informed him that he had a match: A half-brother from South Carolina called Allen Henderson, who was seven years younger.

Henderson had also approached MyHeritage weeks' before "on a whim just to see where I'm from" after seeing the company advertise its geneological research services on the Fox News channel.

"He had no idea that we were here and, of course, I wasn't looking for him, because I had no idea that he was there," Henderson told local US channel 7News at the end of August.

The discovery of his half-brother softened what was a blow for Gantois: his father had died in 1997, apparently without ever knowing he had a son in France because Gantois' mother Irene had never told him she was pregnant.

On Monday, having already exchanged photos by mail, they came face-to-face on the same windswept beach in northern France where their father landed along with hundreds of thousands of Allied forces in June 1944 to liberate France from its Nazi occupiers.

The two men share a clear physical resemblance, have a black cat and both like plaid shirts.

"People around me say it's incredible how much we look like each other. You'd really say we are brothers," Gantois told AFP.

Furthermore, having seen some of Henderson's pictures, "my father is the spitting image of me, the same smile, everything."

Sadly, for the time being, neither of them speaks the other's language, meaning an interpreter is needed at all times.

"I'll need to start studying English now," said Gantois, who has also gained a half-sister, Judy, 70.

As for his father, though he never met him Gantois says he has already visited his grave in a military cemetary in Los Angeles.

The number of children born in France to American servicemen is unknown, a local historian Emmanuel Thiebot told AFP.

There were an estimated 200,000 children born to Germans, according to official figures.