Jacob Mok was a son of Machiel Philip Mok and Klara Brandon. He was born on December 8, 1875 in Haarlem and in his younger years he was a cantor and later in life he became a traveler in stationery. On 30 June 1897, he married Mietje Brandon in Amsterdam, a daughter of Isaac Jacob Brandon and Rosa Groenewout, who was born in Amsterdam on 24 February 1875. Mietje then lived at home with her parents, brothers and sisters at Lange Houtstraat 130 and Jacob lived with his family at Uilenburgerstraat 29C
After Jacob and Mietje's marriage took place in 1897, they left for Hilversum, where they lived at Zeedijk 28 and where their four children were born. On 4 May 1903, Jacob left with his wife and children (Michel (1898), Izak (1899), Philip (1901) and Rosalie (1902) for Antwerp, where they were given living space at Burburestraat 37. Their fifth child was born there in 1904: son Emmanuel born.
The Mok family remained in Belgium until Jacob returned to Amsterdam with his wife and children on 4 July 1908, where they lived for about 9 months at Zwanenburgwal 38, but moved to Vrolikstraat 203 II in Amsterdam-East on 22 March 1909.
It now turned out that the marriage of Jacob and Mietje was not a success, because Jacob left for Rotterdam on 25 February 1914, where he found living space at Gedempte Botersloot no. 52a at the home of the widow Van der Werf. According to notes on Jacob Mok's Rotterdam registration card, he was already living separately from his wife Mietje and the children. They had been living at Vrolikstraat 279 in Amsterdam since the beginning of December 1913.
On 24 December 1913, Jacob Mok was sentenced to four months in prison for embezzlement by the Amsterdam District Court. Four months later, on 22 April 1914, Jacob left for Antwerp again and was registered at Brederodestraat 51. Shortly afterwards it was discovered that Jacob Mok lived in an unfurnished room in Antwerp at Hof te Bekestraat 43, where he lived in concubinage with a a certain Mina van der Graaf and with whom Jacob left for Vredestraat 44 in Berchem in June 1914.
Jacobs' legal wife Mietje Brandon had moved from Vrolikstraat 279 to Valkenburgerstraat 180 in Amsterdam on 26 June 1914 and provided a living for herself and her children as a shopkeeper selling household items. However, she died on 5 June 1915 and was interred in the Jewish Cemetery in Diemen.
The children were placed with relatives after the death of their mother. Only Michel then went to live on his own, but his youngest brother Emmanuel came to live with him; Izak was placed with his uncle Philip, a brother of his father Jacob Mok; Philip was placed with Jechiël Ritmeester who was married to Elisabeth Brandon, the sister of his mother Mietje; Rosalie also went to one of her father's brothers, uncle Emanuel Mok. But both Emmanuel and his sister Rosalie were placed in the Bergstichting in Laren on 13 November 1915.
The now widowed Jacob Mok had returned from Antwerp (Berchem) to Rotterdam and then lived again with the widow Van der Werf, now at Agnietenstraat 94. In May 1917, Jacob left for Cologne, from where he returned to the Netherlands four months later and was registered at Koningin Emmakade 117 in Den Haag on 29 September 1917.
On 23 November 1917 he married again in Den Haag, this time with the non-Jewish Maria Petronella Werkhoven who was born there and with whom he lived at Helmersstraat 71 and Loosduinseweg 947. After more than 16 years of marriage, she died at the age of 58 on 19 September 1933 in Den Haag. Jacob then married for the third time on 23 February 1934 in Den Haag to Georgzette Petronella Hielckert, who was also non-Jewish and born in West Java. After the marriage was concluded, Jacob and Georgette moved into a house at Galvanistraat 6 in The Hague, where Jacob Mok eventually died during the war on April 6, 1944.
Sources include the City Archive of Amsterdam, closed down family registration cards with Jacob Mok (1875), with Machiel Philip Mok (1848); Amsterdam family registration cards of Michel Mok (1898), Izak Mok (1899), Emanuel Mok (1876) en Jechiël Ritmeester; website wiewaswie.nl/marriage Jacob Mok x Mietje Brandon; website stenenarchief.nl/grave of Mietje Mok-Brandon; the City Archive of Rotterdam, registration card of Jacob Mok; website Open Archieven/marriage Jacob Mok x Maria Petronella Werkhoven; Municipal Archive of Den Haag, family registration card of Jacob Mok; Felix archief Antwerp, dossiers of foreigners of Berchem 8829 and 8879 and of Antwerp 106501 and the certificate of death nr. A822 of 7 April 1944 for Jacob Mok, made out in Den Haag.