As for Jewish names, "Polak", "Cohen" and "Grunberg" are the most common Jewish last names in NL.
It is known that Jews were always adopting their names from other nationalities as from Polish nationals or Germans, it all depended on the circumstances at the time and what they personally wanted to achieve from such a name change. Like ie: for the immigration purposes.
I just wonder, if they actually know their original Jewish names today, not the adopted ones which were changed over and over again.