CONSANGUINITY Directly at the beginning of the study, it is striking that not only the mother of Nicoletta (Elisabeth Catharina), but also the paternal grandmother (Nicolette Apolonia) is a Ruigrok. The question then immediately is: are they perhaps relatives? And indeed they are relatives, but many generations back, as shown in the diagram below.

The above diagram is actually a small partof the pedigree chart of Nicoletta Catharina Maria Zeestraten. If some persons have common ancestors, the number of ancestors is smaller than you'd expect in principle. This is called the reduction of pedigree chart. In the above diagram is that the case at multiple locations. Leendert Jans Ruijgrok and Crijntje John Langeveld are the ancestors of Elisabeth Catharina and Nicolette Apolonia Ruigrok (indicated in red). But the pedigree of the mother Apolonia Ruigrok includes members of the Ruijgrok family as well. They are related with the Ewout-branch by marriage. OTHER RELATIONS There are more examples of a marriage between Zeestraten and Ruigrok: In 1968 Henry Arnold Ferdinand Ruigrok (1942-2000) married with Magdalena Zeestraten (1945-?) and Johannes Antonius Zeestraten (1905-1977) married in ??? with Clasina Maria Ruigrok (1915- 1982). Another example is the marriage of Anna Margaretha Maria Ruigrok (1925-?) and Cornelis Peter de Groot (1920-1989), son of Adrian de Groot and Maria Wilhelmina Zeestraten, in 1946. The families Ruigrok and Zeestraten are also related to each other in other ways, as indicated in the diagram below.