According to the 1834 census, Heinrich Gulau died in 1825. He was not noted to have a wife or any children. If he was in fact married and had daughters, his widow may have remarried and taken their daughters to live with her in her new husband's family. It does not appear he had any boys, or they would have been listed in the census.
Head of the Household Heinrich Gulau, age 22 in 1816, deceased 1825
↑The 1775 and 1798 Census of the German Colony on the Volga, Lesnoy Karamysh, also known as Grimm; Published by the American Historical Society of Germans from Russia, Lincoln, Nebraska, USA; Published date: 1995; family #14 in the 1798 census, Matthias Gulau family.
↑1834 Census of Grimm in the District of Saratov, Russia, dated 2 February 1835; Translated by Brent Mai, Concordia University, Portland, Oregon; Published by Dynasty Publishing, Beaverton, OR, USA; Published 2011; page 86, family #315, Heinrich Gulau.