The thesis of this project is that all Swiss Deiss/Deis families will share a Y chromosome, that we are basically one family that started in Herznach, Oberzeihen and Unterzeihen in Canton Aargau, Switzerland. Even though we only have six members at this point I feel that the point has been made that this is very likely to be true. My "Patriarch" was originally Jakob Deiss and a member from Switzerland had a "Patriarch" named Kaspar Deiss, and we match at 65 of 67 markers. We didn't know the relationship between Jakob and Kaspar until recently, when our Swiss member did enough research in ancient church book records to find their common ancestor some dozen generations back.
I think German Deis/Deiss/Theiss families are probably different and perhaps that point has also been made by our other members. I hope we get lots of members so that we can show relationships outside of Switzerland as well. Now it appears that German Deiss/Theiss families fall into the I2b or R1b1a haplogroups. I have seen some close matches with our members on Ysearch but have not managed to talk those people into joining us here.
The "Y results" page shows us as the "G" haplotype. But I already knew I was G2a, which doesn't perfectly match the plain G haplogroup. And our newer member from Switzerland has joined the Haplogroup G Project where he learned that his entire haplogroup was G2a3b1a2, and I match him closely, so I think that is our full Y haplogroup designation.
The Romans divided present-day Switzerland into Helvetia (west) and Raetia (east). The Helvetians were Celtic, but the Raetians spoke a language close to Etruscan, which has been lost, and does not relate to existing European languages. The Etruscans had an origin myth that they had come from Asia Minor (modern Turkey) -- parallel perhaps to the story in the Aeneid for Romans. The G2a haplogroup is most common today in the Caucasus, and rather rare in Europe, so I am thinking that the ancestors of the Swiss Deiss family were Raetian. The Allemani came later.
When I looked at a map of where G2a3b1a2 occurs in continental Europe, (not including the British Isles) 3 locations showed up. Canton Aargau Switzerland, Strasbourg in Alsace, and Amsterdam. There appears to be a different surname in Amsterdam, but it appears there was a Swiss emigration to Alsace after the 30 Years' War. So I think it is likely that Alsatians named Deiss are members of our family from Canton Aargau -- and this could include the famous wine-maker Marcel Deiss. If we can get any Alsatian members perhaps this question can be resolved. One of our "German" members has relatives in a town close to Alsace so R1b1 is another possibility.