His extraordinary story was supported by a compelling set of evidence, in France and Germany, published in the latest edition of Le Point magazine in Paris.
Hitler allegedly had an affair with Mr. Loret’s mother, 16-year-old Charlotte Lobjoie, when he was leaving the trenches in June 1917.
Although he fought the French near Seboncourt, in the north of the Picardie region, Hitler went to Fournes-in-Weppe, a small town west of Lille, for a regular leave.
There he met Miss Lobjoie, who later told their son, “One day I was burying hay with other women when we saw a German soldier across the street.
“He had a sketch and seemed to draw. All the women found it interesting and were curious to know what he was drawing.
“I have been appointed to approach him.”
The pair began a brief relationship, culminating in the birth of Jean-Marie, born in March 1918 after being conceived at an “overflowing” party in June 1917.
Miss Lobjoie then told Jean-Marie: “When your father was there, which was very rarely, he liked to take me to the country.
“But these walks have usually ended badly. In fact, your father, inspired by nature, made speeches that I did not really understand.
“He did not speak French, but only in German, speaking to an imaginary public. Even if I spoke German, I could not follow it, like the stories of Prussia, Austria, and Bavaria, where I did not know myself at all, far from it.
“My reaction used to marry your father so much that I did not show any reaction.”
Jean-Marie was, like thousands of other French children with fathers German soldiers, poorly treated by his peers at school.
He was referred to as “Bosh’s son”, and often fought trying to defend his father, who had disappeared outside the border in Germany.
Miss Lobjoie, meanwhile, refused to discuss Jean-Marie’s father and ended up giving his only son to his adoption in the 1930s to a family called Loret.
His real father did not recognize Jean-Marie, but kept in touch with Mademoiselle Lobjoie.
Incredibly, Mr. Loret continued to fight the Germans in 1939, defending the Maginot Line before being bypassed during the Nazi invasion, resulting in occupied France from 1940 to 1944.
Mr. Loret even joined the French Resistance, and received the code name ‘Clement’.
Just before her death in the early 1950s, Mrs. Lobjoie finally told Jean-Marie that her father was probably the most infamous dictator in the history of humanity.