Johann married Johanne Christiane Friederike Ulmer 4 May 1873. Johanne (daughter of Conrad Ulmer and Sibylla Christiana Obenland) was born 11 Jun 1843. [Group Sheet]

1. Ernst Friedrich Agster was born 4 Jun 1883, Ilsfeld, Heilbronn, Baden-Wurttemberg, Germany; was christened 10 Jun 1883, Ilsfeld, Heilbronn, Baden-Wurttemberg, Germany.
2. Ernst Wilhelm Agster was born 23 Sep 1886, Ilsfeld, Heilbronn, Baden-Wurttemberg, Germany; was christened 3 Oct 1886, Ilsfeld, Heilbronn, Baden-Wurttemberg, Germany; died 9 Sep 1914.
3. Maria Agster was born 7 Oct 1884, Ilsfeld, Heilbronn, Baden-Wurttemberg, Germany; was christened 12 Oct 1884, Ilsfeld, Heilbronn, Baden-Wurttemberg, Germany.

Jakob — Sybille Wolz. [Group Sheet]