Vincent van Gogh may have been a somewhat repressed homosexual.
Apparently Vincent was manic-depressive or bi-polar.
One can speculate about how many alleged manic-depressives were homosexual. (Hans Christian Andersen, Charles Baudelaire, Ludwig van Beethoven, Lord Byron, Winston Churchill, Ralph Waldo Emerson, Ernest Hemingway, Florence Nightingale, Robert Louis Stevenson, Mark Twain, Virginia Woolf...)
As a youth, Vincent Van Gogh, the Dutch Post-Impressionist, was fervent about religion.
However, during the 1870s, he failed the various exams which would have allowed him to become a pastor or a missionary.
In 1980, Vincent began his career as a painter.
In 1882, Vincent began very briefly living with an alcoholic prostitute, Clasina Maria Hoornik, known as Sien. During the year 1882, Sien gave birth to a baby boy called Willem and Vincent spent three weeks in a hospital suffering from gonorrhoea.
Willem came to believe he was Van Gogh's son, but the timing of the birth makes this unlikely.
In 1883, Vincent abandoned Sien.
In 1885, Vincent was getting young peasant girls to model for his paintings. He was accused of making one of them pregnant.
In 1886, while living in Antwerp, Vincent began to drink absinthe heavily and may have been treated for syphilis. 
Starting in 1887, Vincent began writing letters to his young friend Emile Bernard. In these letters Vincent revealed that when he had the money, he tried to visit a brothel about every two weeks.
Also in 1886, Vincent moved to Paris, where he shared a house with his brother Theo.
In 1887, Vincent met and befriended Paul Gauguin, who had just arrived in Paris.
Some writers believe that in Paris Vincent discovered a world of gay sex.
There has been speculation that Vincent felt sexually attracted towards Paul Gauguin and that Vincent had a very close relationship with his brother Theo.
Paul Gauguin is said to have flirted with Van Gogh and Theo, but to have preferred much younger men. (Paul Gauguin's erotic life - Page 3 - Salon.com)
Albert J Lubin, in his book Stranger on the Earth: A Psychological Biography of Vincent Van Gogh, suggests that Vincent may have been sexually attracted to Gauguin.
Vincent's move from Holland to Gay Paris seems to have led to the production of some brighter, sunnier, more joyous paintings.
On the other hand, there is still the feeling in some of the French paintings that Vincent is repressed and has still not learnt to live at peace with himself.
By 1888, Vincent was living in Arles, in the South of France. He worked alongside Paul Gauguin.
The same year, Vincent's friendship with Paul Gauguin came to an end, and Vincent cut off part of his left ear.
YouTube - Vincent & Theo (gay kiss between Vincent and ...
Some van Gogh paintings: