I've been researching my wife's genealogy and have run into the same interesting connection. I've managed to trace her maternal grandmother back through long Mennonite lines, first in Waterloo Canada, then back to the German, and finally Switzerland. My wife's three times Great Grandmother was Elizabeth Frey, born to a Mennonite family in Woolwich Township where there are several references to her husband Isaac Reitzel who was mentioned a couple of times in the local Berliner newspaper. Apparently the Waterloo area is for Mennonites in the New World what Lancaster PA is for the Amish. You can apparently still go there and see carts and buggies, though I've never been myself.
Elisabeth's father was born in Germany and several generations of Freys, all Mennonite, lead back to Hans Jagli (Jacob?) Frey (c.1642) who marries Barbara Oberholzer. The Oberholtzer Family Association has an extensively researched Genealogy that includes information about Veronica's grandfather Martin who was an early Anabaptist and was murdered by rival Zwiglians. Apparently not only did Lutherans and other Protestant sects as well as the Swiss Catholics all hate the Anabaptists, but the Anabaptist splinter groups all had hate to spare as well! When Martin was murdered by drowning at age 75 (That was apparently the "preferred" method of killing anabaptists. Ferdinand I called it the "third baptism" since Anabaptists believed other Christian converts needed to be "Rebaptised" as adults, hence the name. Nasty stuff.), his various children had already fled Switzerland to the German Palatine because of ill treatment. Without intending to compare the historical treatment of Mennonites with that of the Jewish community in Europe and elsewhere, Anabaptists in Switzerland were not allowed to own land, gather together in groups bigger than 20, meet any Christians on Sunday, marry non-anabaptists, were similarly taxed and faced regular violence. It was because of this that Martin's children fled to Germany and then his son Marx's family to Pennsylvania where they got land from William Penn and added their DNA to the Pennsylvania "Deutsch".
But Hans Jacob Frey's line goes back to Jakob Wyss (b, 1549) and Madalena Sporri (b. 1560) who were married in the town of Weisslingen, Northwest of Zurich in 1580. I found a document of their marriage in the Zurich Canton library. It does not mention their religion though or their baptisms, only that he was a Carpenter. I'm a history teacher, but my expertise is NOT in 16th century Austrian Hapsburg Empire drama. Still, my understanding is that the area around Zurich was under the sway of the Empire and much more sympathetic to Protestants and Jews alike than the rest of Catholic Switzerland. Please correct me if I am wrong. It's possible that he was a convert to the rising tide of Protestentism or a Catholic, but it's hard to know since the first reference I can find to the Anabaptists is in reference to Han's son who is described as a widower and an Anabaptist in the records of his second marriage.
But here's where things get interesting. Three of my wife's grandparents were immigrants from small Norwegian fishing and farming villages and they have extensive family records, so we assumed she'd be nearly all Scandanavian. However, when my wife had her DNA done, she was 10% Jewish. It must come from that Mennonite line and can't be too far back. Although I don't have records before Jakob Wyss, there are lots of sites that seem to trace Jakob (without citation) back through various Wyss, Sporri, Schenkel and Johr families to Nathan Halevi Wyss (Weiss?) who was buried in 1535 in the Jewish graveyard at Endingen Switzerland. From there, people tie back to Rabbi Weil and others like Paul of Burgos. If anyone out there has more info on this, I'd love to see it.
If this is a real connection, it explains my wife's Jewish DNA and seems to verify casual comments I've read online about Jewish conversion to the anabaptist faith generally and the Mennonite faith more specifically. There is a article about Weisslingen on the website of the Mennonite church which says something similar. Whether these were forced, coerced, a matter of survival, or heartfelt, I can't say. Frankly, I have no horse in that race. But if these conversions were for appearance sake or to protect their families, I wonder why they would choose a sect that meant continued persecution and violence?
I know that the Jewish community suffered horribly in Switzerland in the second half of the 14th century and were forced out of much of the country, but there had to have continued to be Jewish communities in the country for Nathan Halevi to be born near Zurich a century later. I recently contacted a librarian in the town of Weisslingen who informed me, to my surprise, that not a single Jew lived in Switzerland between 1400 and 1700! So maybe I'm wrong!
Anyway, if anyone has any sources or information about a possible connection, I'd be fascinated to hear it.