Some more info I found here about the Korthofs:
http://www.freewebs.com/korthof/Aart Korthof was born on March 16, 1866 in Amsterdam. He was a shopkeeper and merchant. He was the son of Gerrit Korthof and Sophia Kaarls. He was married on February 25, 1889 in Renville, MN to Amelia (Molly) Henning, who died on December 20, 1908 in Hennepin County.
Gerrit Korthof was born on December 17, 1824 in Muiderberg. He was a milkman, barnkeeper and carpenter He died on December 29, 1892 in Nieuweramstel, and was the son of Huibert Korthof and Aaltje de Bruijn. He was married on May 16, 1847 in Sloten to Sophia Kaarls, born August 24, 1828 in Amsterdam, died on September 7, 1875 in Amsterdam, daughter of Andries Kaarls (farmer) and Marritje de Haas.
Huibert Korthof was born on May 20, 1785 in Muiderberg, baptized on June 30, 1786 in Muiden. He was a laberor, digger and peasant. He died on May 11, 1852 in Muiderberg, and was the son of Jan Hendrikz Korfhof and Hendrijntje Hendriksdochter Donkervoort. He was married on February 19, 1808 in Muiderberg to Aaltje de Bruijn, baptized on April 23, 1786 in Nieuw Loosdrecht, died on February 8, 1827 in Muiderberg, daughter of Aart den Bruin (tailor) and Aaltje Jens de Groot.
Jan Hendrikz Korthof was born on May 22, 1750 in Huizen. He was a gardener and laberor. He died on December 19, 1826 in Muiderberg, and was the son of Hendrik Jansz Korthoff and Weijmpie Jansdochter Makkingh. He was married on December 21, 1777 in Muiderberg to Hendrijntje Hendriksdochter Donkervoort, baptized on July 19, 1744 in Woudenberg, died on October 31, 1828, daughter of Hendrik Eersten and Sophia Hendriks. The family crest of Jan Hendrikz Korthof and his descendants:
http://www.freewebs.com/korthof/familiewapenkorthof001.pdfHendrik Jansz Korthoff was baptized on June 2, 1721 in Huizen and buried on December 12, 1750 in Huizen. He was the son of Jan Roelofsz Korfhoff and Maria Adriaans van Dijk. He was married on September 28, 1749 in Huizen to Weijmpie Jansdochter Makkingh, baptized on November 16, 1727 in Huizen, died on November 1, 1804, daughter of Jan Andries Makkinje and Marritje Claessen.
Jan Roelofsz Korthoff was baptized on November 8, 1676 in Naarden and died on October 27, 1734. He was the son of Roelof Stevensz Korthoff and Stoffelijntje Stoffels. He was married on June 18, 1708 in Huizen to Maria Adriaans van Dijk, born in Utrecht, died October 27, 1734. She was probably the daughter of Adriaan van Dijk and Maria Minnebeek.
Roelof Stevensz Korthoff was born between 1635 and 1638 and was a turf carrier. He died on March 21, 1679 in Naarden. He was the son of Steven Jacobsz Cortof and Grietje Reijers Tulling. He was married on May 16, 1658 in Naarden to Annetje Jans, born circa 1638.
Steven Jacobsz Cortof was baptized on April 5, 1615 in Naarden. He was a sea captain, brewer and municipal executive. He was buried on July 31, 1651 in Naarden. He was the son of Jacob Stevens and Emmetgen Teunis. He was married to Grietje Reijers Tulling, baptized on July 2, 1617 in Naarden, buried in Naarden on November 13, 1662 and was the dauhter of Reijer Anthonisz Tullingh (major of Naarden) and Jannetje Jans.
Jacob Stevens was born circa 1585 and was a gasthuismeester (master of some type of hospital), municipal executive and poorter (someone who had acquired the right to live within the city gates of a city). He died on December 1, 1632 in Naarden. He was the son of Steven Jansz. He was married to Emmetgen Teunis.
Stevens Janz was born circa 1555 and was poorter in Naarden. He died in 1612 in Naarden. He was the son of a certain Jan, who was the tribal patriarch of one of the three Dutch Korfhof families (the Noord Holland branch).