Fans of the pioneering American aviator Charles Lindbergh have had to swallow a few uncomfortable facts about their hero over the years, such as his sympathy for the Nazis, his campaigning against the involvement of the United States in the Second World War and his anti-Semitism.

Now comes a new, seemingly incontrovertible bit of awkward news: DNA evidence confirming that Mr Lindbergh, who made the first solo flight across the Atlantic Ocean, had a secret, second family in Germany with a Munich hatmaker, Brigitte Hesshaimer. Anton Schwenk, a spokesman for the family, announced yesterday that DNA tests, conducted by the LMU Institute in Munich, had established a 99.9 per cent likelihood that the most famous US airman of the 20th century was the father of Dyrk Hesshaimer, David Hesshaimer and Astrid Bouteuil.

Mr Schwenk said: "They knew all along he was their father because they spent time with him growing up. But it's good to have an iron-clad confirmation. It's a delightful moment for them because they now have a feeling of belonging."

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But "delightful" is not quite the word to describe the reaction of Mr Lindbergh's descendants and defenders in the US. They had resisted the notion, preferring to idolise their hero along the lines of Jimmy Stewart's straight-arrow performance in the 1957 biopic, Spirit of Saint Louis. Mr Lindbergh's biographer, A Scott Berg, said in the summer it was "chronologically and geographically possible" but contradicted everything he knew about his subject's character. In many ways, the forced historical revision is reminiscent of earlier DNA tests confirming the long-held claim that Thomas Jefferson, one of the US's founding fathers, had sired children with one of his slaves.

One of Mr Lindbergh's American grandchildren, Morgan Lindbergh, has admitted that the German family looked "hauntingly familiar". He travelled to Europe in the summer to meet the Hesshaimers and agreed to also take a DNA test. The rest of the American family has said nothing in public and probably intends to keep it that way, but Mr Schwenk said yesterday that an initial frostiness had now thawed. There had been "amiable meetings as well as regular contacts with letters and calls" across the Atlantic, suggesting the possibility of a whole new nexus of family relationships, he said. "I'd say it's not a happy end to the story but a happy beginning."

It helps that the German family is interested only in setting the historical record straight. It is not asking for money ­ Lindbergh apparently provided generously for them as they were growing up ­ and deliberately waited until after the death of their mother before making the issue public.

The three children of Ms Hesshaimer stood out in the relatively conservative atmosphere of post-war Bavaria because their mother was a single parent. They have strong memories of a tall, greying American who would drop in once or twice a year, cook big breakfasts of sausages and pancakes and tell tales of his travels around the world.

Ms Bouteuil explained in a series of interviews over the summer that she and her brothers knew this man was their father, but were otherwise clueless about his identity. It was only after Mr Lindbergh's death in 1974 that they began to realise who he was.

In the early 1980s Ms Bouteuil found a stash of 100 love letters to her mother, signed with the initial "C", along with a magazine article about Mr Lindbergh. The letters were stuffed into a black bin bag and sealed with a red ribbon.

At that point Ms Bouteuil confronted her mother, who acknowledged Mr Lindbergh was the father, but begged her children not to make the fact public while she was still alive. Ms Hesshaimer died in 2001, at the age of 74.

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The couple met in 1957 in Munich, where Mr Lindbergh was discussing a deal to translate one of his books into German with one of Ms Hesshaimer's friends. Ms Hesshaimer was then 30; 25 years younger than Mr Lindbergh, and in poor health following a bout of bone tuberculosis several years earlier.

Dyrk Hesshaimer was born in 1958, Ms Bouteuil in 1960 and David Hesshaimer in 1967. Mr Lindbergh used a pseudonym, Careu Kent, when he was in Munich, and the children believed he was an author because he was constantly writing and carrying papers. The mystery was heightened by the fact that the children spoke little English and Mr Lindbergh spoke no German.

Now that the secret is out, it has led to a media feeding-frenzy, especially in Germany. The news magazine Focus reported in the summer that Mr Lindbergh may have also had an affair with Ms Hesshaimer's sister, Marietta, fathering her two sons, who were brought up in Switzerland.

Marietta Hesshaimer, who is still alive, has refused to have anything to do with the investigation. She and her two children have refused to undergo DNA testing.

None of this takes away from Mr Lindbergh's reputation as the quintessential expression of American derring-do in the early days of aviation.He braved the skies repeatedly in planes nicknamed "flying coffins" and having a series of narrow escapes in the test flights leading up to his legendary crossing from Long Island, New York, to Le Bourget, near Paris, on 21 May 1927.

But it does put a considerable dent in Mr Lindbergh's image as a wholesome family man. He and his wife, Anne Morrow Lindbergh, had six children together during a 45-year marriage and garnered considerable sympathy when their first-born, Charles Jr, was kidnapped and murdered under bizarre circumstances before his second birthday.

The Lindbergh baby story turned into a media circus similar to the OJ Simpson trial six decades later. A German-born carpenter who had fought against the US in the Second World War was eventually arrested and sent to the electric chair on the most tenuous of evidence. That spawned a mini-industry in alternative theories of the crime, including speculation that Ms Morrow Lindbergh's sister, Elizabeth, killed the baby out of jealousy because Mr Lindbergh had not married her. The celebrated satirist HL Mencken described the trial in characteristically biting terms as "the greatest story since the Resurrection".

It certainly did no harm to Mr Lindbergh's reputation. The image of him as the terribly wronged father went a long way to allay outrage a few years later when he travelled to Germany on the eve of the Second World War to accept the German Eagle award from Hermann Goering.

There were many hints over the years that the Lindberghs kept a less-than-harmonious household. In the last 20 years of his life, Mr Lindbergh was travelling almost constantly, and paid only infrequent visits to the family estate in Connecticut.

He died of cancer in Hawaii. Ms Morrow Lindbergh, who moved to Vermont, died in 2001 at the age of 94.