Now, particularly in isolated areas, it is not unusual for a pair of siblings to marry another pair of siblings. The difficulty here is that researchers can't seem to agree on which of these pairs is the father of Thomas Brouwer Bancker born about 1729 (or perhaps a bit later) and married in 1754 to Annatje Mabie and this is one of my direct lines!
Pearson in his First Settlers in Schenectady lists Johannes and Magdalena as Thomas' parents but Howard Banker in The Bancker Genealogy lists his parents as Willem and Annatje. I started to lean towards Willem and Annatjje because Thomas named his first daughter Annatje but then realized duh! his wife was named Annatje so there went that scrap of thought.
The Vader Genealogy (Veeder family) states that Thomas was baptized 8 Dec 1729, in the Bancker Genealogy it is given as born 8 Dec 1729. Confusion between baptismal and birth dates is common in Dutch Colonial research but generally speaking baptismal dates are close to the birth date so Thomas was probably born towards the end of 1729. Now, Willem is certainly old enough to have a son in 1729 and had married Annatje 17 Dec 1726. Johannes on the other hand is perhaps 18 or 19, old enough yes but customarily most men were into their 20's when they had children. The date of his marriage to Magdalena is unknown.
Willem's children are listed with clear birth/baptismal dates and there is a gap that just fits Thomas. Johannes's two known children, Elisabeth and Gerrit, are listed in 1735 and 1737, a big gap from 1729. Willem and Annatje "feel" right but there is absolutely nothing I have found YET (notice the smidge of hopefulness) to truly indicate one or the other. Perhaps someone will find Thomas' baptismal record and it may list parents???
Have you had any knotty problem in your research that made you crazy and gave you headaches? Did you ever get it solved?