There are no photographs of her parents in the bungalow in Miami’s Little Havana where Alina Fernandez Revuelta lives. But she need only glance at the triangular birthmark on her left arm to be reminded of the illicit union that led to her conception. The skin blemish runs in the family of Fidel Castro.

When Alina was a few months old, Castro dispatched one of his sisters to check if the infant bore the mark. Only then did he accept she was his. Ten years later, Alina’s mother, Natalia “Naty” Revuelta, told her the man who sometimes visited their house at night, enveloping the girl in clouds of cigar smoke and, once, giving her a bearded doll dressed in olive-green uniform to look like himself, was her father. When she was 12, Castro conceded Alina could carry his name. After a childhood of neglect, of being ignored when she wrote begging him to visit, she refused. By then Castro was firmly entrenched as Cuba’s Maximo Jefe — maximum leader — a position he would hold for nearly half a century, until anointing his brother Raul president earlier this year.

The chaos Castro’s communist regime has wrought on one of the most beautiful islands in the Caribbean has seen more than 2m of his countrymen flee into exile. But it is his personal path of destruction through the lives of those closest to him, the legions of women he has slept with and the children they have borne him, that has, until now, been a closely guarded secret.

Castro’s private life has always been strictly taboo in Cuba’s state-controlled media. He has rarely been photographed with any of the women he has been involved with, and whenever such pictures have appeared, the women have been captured coincidentally, in the background.

The overwhelming image of Castro for 50 years has been that of a lone, ranting David taking on every capitalist Goliath, especially the US. Castro long ago made a cold calculation that his power would only last if his countrymen, and the rest of the world, did not really know him.

“He was good at PR,” says Alina, a diminutive 52-year-old with doleful brown eyes. “He always portrayed himself as this lonely man with a beard and cigar, fighting imperialism 24 hours a day with nothing else on his mind.” Nothing could be further from the truth. As his countrymen brace themselves for the mandatory flag-waving that will accompany the 50th anniversary of the revolution next month, Alina and others who fled to the “city of worms”, as the Cuban strongman calls Miami, are stripping away Castro’s mask. The picture they paint is of a serial philanderer with an unknown number of progeny.

"My mother always said he was very passionate,” says Alina. Castro wooed her mother, a green-eyed high-society belle, with feverish letters written from prison, when he was incarcerated between November 1953 and May 1955 after his first attempt to overthrow Cuba’s despised dictator Fulgencio Batista. They begin, “My dearest Naty”, “My incomparable Naty”. “You’re audacious and I like that. I am on fire. Write to me, for I cannot be without your letters. I love you very much.”

“When you’re in jail you have all the time in the world to become a poet, a manipulator, a psychologist,” Alina says. She has reason to be bitter. She and her mother suffered at Castro’s hands. So did the woman he was married to when he was declaring his love for Naty. Mirta Diaz-Balart had already borne Castro a son, Fidelito, or Little Fidel, four years old when his father was jailed. Castro met Mirta through her brother, a fellow law student at Havana University, and pursued her despite opposition from her family, which had connections to the Batista regime and thought him beneath her. Castro was the third of seven children born out of wedlock to a domestic servant, Lina Ruz Gonzalez, and her master, Angel Castro, a peasant who became a wealthy sugar-plantation owner. During his early years, Fidel and his siblings lived with their mother in a shack adjoining the house where Angel lived with his wife and their two children.

At the age of five, Castro and two siblings were sent to live with impoverished Haitian foster parents. He was then sent to a Jesuit boarding school in Havana, where, though a brilliant student, he was bullied for being illegitimate and not baptised. “His psychological make-up comes from being a bastard, a second-class citizen in his own home, who grew up determined he’d never be made to feel that way again,” says Andy Gomez, assistant provost at Miami University’s Institute for Cuban and Cuban-American Studies. “Since he had little sense of identity as he was growing up, he created his own” — one that would always be in control, never again dependent on anyone, least of all a woman.

“I’ve a feeling that deep down he may be shy and emotionally vulnerable,” Alina concedes.

Castro was well into his teens before his father dissolved his first marriage and married Lina. From then on, it seems his parents indulged him materially, paying for a lavish honeymoon when he married Mirta in 1948. But he soon tired of his bride, who had little interest in politics. Sure that armed struggle could overthrow Batista, he was fast becoming a charismatic champion of social justice and national sovereignty, and his attempts to foment revolt were attracting followers, including Naty Revuelta. Also married, but bored, she sold her jewels for the rebels to buy weapons and sent Castro the key to her home (in an envelope laced with perfume) so that he could hold clandestine meetings there. Their relationship was still platonic when Castro was jailed. But he was infatuated with the woman once described as having the looks of a movie star “dipped by the gods into a golden oil, like Ava Gardner and Rita Hayworth”.

By this time Mirta’s family connections with the Batista regime had driven a wedge between her and Castro, and in one letter to Naty he joked cruelly that at least prison gave him some peace from domestic arguments: “I’m going to write to the [prison] tribunal reproaching them for having sentenced me to 15 years rather than 200.” Two letters Castro wrote to his wife and would-be lover were switched. When Mirta read what had been meant for Naty she was devastated, filed for divorce and quickly married again, moving with Fidelito to New York. Castro vowed revenge, writing to one of his sisters from prison that he could not bear to think of his son sleeping under the same roof as “my most repulsive enemies”.

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