Hi, thanks for the intrest.
I can read German, and using that combined with google translate I understand Dutch too, but it takes a long time.
There is several conflicting pices of information about Jan Wessel (born ca. 1580). As you see there is an even earlier source of a Peter Wessel from Germany, but there is no evidence he is the father of Jan. According to an old newspaper article (which I am not able to get hold of) the familyname Wessel originates from Wesel i Westphalen (which I believe was a part of Germany).
However Wessel is a common Duch name and Jan Wessel found a duch wife. So even the question of what country they come from is unsetteled.
About the many children I agree that it is a lot, hovever 12-15 children was rather common in Norway at that time. Henrik Jansen Wessel supposedly also had 12 sons and a couple of daughters. However the church records for that particular curch and time has been lost so we lack accurte information about his children.