Jan was the son of unknown parents. The date and place of his birth have not been found.
He had two marriages/partners. His first wife was Ludmilla of Strakonicz. They were married, but the date and place have not been found. Their only known child was Johanka (1425-1475).
His second wife was Eliška z Kravař. They were married, but the date and place have not been found. They had no known children.