Vincent van Gogh had five siblings: Theo, Cor, Anna, Elisabeth and Wil. Vincent was the oldest surviving child in the family of Theodorus van Gogh and Anna Cornelia Carbentus.
His younger brother Theo became the most important person in his adult life. Theo worked as an art dealer, supported Vincent financially and emotionally, and exchanged hundreds of letters with him. Their correspondence is one of the key sources for understanding van Gogh's ideas and working methods.
The family also included Vincent's brother Cornelis, known as Cor, and three sisters: Elisabeth, Anna and Wil. A stillborn brother named Vincent had been born exactly one year before the painter, so he is not counted among the five living siblings normally meant by this question. This distinction explains why some family summaries can appear confusing.