Jan Pietersz Neefjes was born 6 August 1765 in Zwaagdijk, North Holland, Netherlands to Pieter Neefjes (1742-1801) and Trijntje Ettes (c1740-1775) and died 2 June 1841 Hoogkarspel, North Holland, Netherlands of unspecified causes. He married Trijntje Jonge (1770-1811) 31 May 1800 in Hauwert, North Holland, Netherlands. He married Maria Meester (1783-1858) 1 February 1816 in Hoogkarspel, North Holland, Netherlands.
Children
| Name | Birth | Death | Joined with |
| Cornelis Neefjes (1806-1887) | 30 April 1806 Hauwert, North Holland, Netherlands | 21 December 1887 Westwoud, North Holland, Netherlands | Aagje Vriend (1809-1831) Aaltje Stam (1811-1860) Marijtje Suiker (1806-1890) |
| Name | Birth | Death | Joined with |
| Catharina Neefjes (1818-1875) | |||
| Pieter Neefjes (1823-1904) | |||
Siblings
| Name | Birth | Death | Joined with |
| Jan Neefjes (1765-1841) | 6 August 1765 Zwaagdijk, North Holland, Netherlands | 2 June 1841 Hoogkarspel, North Holland, Netherlands | Trijntje Jonge (1770-1811) Maria Meester (1783-1858) |
| Antje Neefjes (1767-1843) | 13 June 1767 Zwaagdijk, North Holland, Netherlands | 27 February 1843 Westerblokker, Blokker, North Holland, Netherlands | Jacob Kooter (1768-1834) |
| Cornelis Neefjes (1770-1820) | 16 December 1770 Zwaagdijk, North Holland, Netherlands | 16 September 1820 Hoogkarspel, North Holland, Netherlands | Aaltje Portegijs (1776-1836) |
| Nantje Neefjes (1773-1822) | 24 March 1773 Zwaagdijk, North Holland, Netherlands | 24 June 1822 Wervershoof, North Holland, Netherlands | Pieter Laan (1771-1826) |
Residences
Footnotes (including sources)
| ‡ General |