Hendrik Jan Coert was born on the 7th of August 1787 in Pijnacker and died on the 2nd of May in 1833 in Hendrik Ido Ambacht. In 1810 he became a Doctor in Hendrik Ido Ambacht. On the 26th of March 1811 he married Neeltje Heijnoordt in Ridderkerk. She was born in Ridderkerk on the 16th of January 1791 and died in Ridderkerk on the 23rd of March 1874. Neeltje was the daughter of Jacob Heijnoordt and Trijntje Lagendijk. They had nine children Johan Hendrik, Trijntje (born on 22nd of May 1814 in Hendrik Ido Ambacht and died in Ridderkerk on the 3rd of September 1905), Jacob, Hendrik Willem, Helena Sibilla, Aplonia Ingelina, Anna Maria (was born in Hendrik Ido Ambacht on the 3rd of May 1825 and died in Dordrecht on the 14th of April 1881), Dirk and Johannes.