In 1917, a young Adolf Hitler was fighting the French in World War I. While he was on a weekend getaway in a local French town, he met Charlotte Lobjoie, a 16 year old with whom he would have an affair. The French teen would become pregnant and give birth to a boy in 1918.
Jean-Marie Loret, who died in 1985 at the age of 67, had fought for the French Resistance in 1939 under the code name 'Clement'. Before his mother's death in the early 1950's, she told him that the dictator was his father.
The rumor had surfaced a few times over the years, but apparently new evidence which seems to support the story is currently being investigated. The above picture alone lends credibility to the theory.