That is a question, that many are still working on the answer, including me. In my work career I frequently traveled throughout Europe.
Some information indicates that the family came from a hamlet named: Ulmet, Rheinland-Pfalz, Germany, which is near Kusel.
Other information points to a village named: Pfaffenberg, Bayern, Germany, which is near Mallersdorf.
In summary, even though I still have friends in the Netherlands and Germany with whom I exchange information, as of this date I do not know the answer. The only thing I am certain of is that they were "Palatines", which narrows the possible origins.
Needless to say if you ever find the answer, I too would like to know.