Jacob Keizer was born 9 January 1879 in Hoogkarspel, North Holland, Netherlands to Meindert Keizer (1851-1926) and Aaltje Commandeur (1852-aft1889) and died 31 July 1954 Hoorn, North Holland, Netherlands of unspecified causes. He married Eva Bos (1879-) 1 February 1904 in Blokker, North Holland, Netherlands.
Children
| Name | Birth | Death | Joined with |
| Alida Keizer (1905-1953) | 19 February 1905 Hoorn, North Holland, Netherlands | 9 December 1953 Hoorn, North Holland, Netherlands | Jan Tol (1904-1992) |
| Anna Keizer (1909-1963) | 24 February 1909 Hoorn, North Holland, Netherlands | 8 July 1963 Hoorn, North Holland, Netherlands | Unknown Jan Tol (1904-1992) |
Footnotes (including sources)
| ‡ General |
| ¶ Death |