One area of culture change we saw in our years with the Banawa (Amazonian Indian tribe) was in the area of music style. When we went there, men & women never sang together. There were two music styles so distinctively different that it was not even possible to sing together. (Not that they didn't sing at the same time. In some odd way which musicians might be able to explain, it actually sounded good together.) When they began having 'church meetings' they were held in the middle of the airstrip, around a pole stuck in the ground, just as the traditional singing was done. But the young people soon created a totally different music style that allowed everyone to sing together, and the singing eventually moved in-doors. It was not any Brazilian music style, either, it was something new. Now if years later, possibly even generations later, some Banawa youth hear recordings of the traditional music, it is possible that they will try to recreate that element of their past culture again. But it will never be quite the same, because some things are always lost in this process. The American Indians and their pow-wow singing & dancing is another example. It is of great cultural significance to them, but it almost certainly does not carry the same meaning as it did before the white invasion and organized suppression of tribal culture.
Getting back to 'conservative Mennonites', I suspect that 4-part harmony accapella singing is an example of this as well. I suspect that while singing w/o instrumental accompaniment is a historical characteristic of the singing style of the past, the 4-part element is something that was added, perhaps to emphasize the difference of accompanied vs unaccompanied singing. (I admit that although I was at one time very much taken with it, I am no longer a fan of this style of singing, because I have heard too much that strikes me as pride in it, and because it 'show-cases' the human voice in a way that distracts from the meaning of the lyrics. I don't think style of music or singing was historically used as an assertion of religious distinctiveness, the way it is sometimes used now. But maybe I am again just viewing all of this from my own cultural background, because I am not an insider to the Swiss Brethren culture. Interestingly, as Ernie makes the point, my children are much more so. But I do hope that as they see the differences in their parents cultural viewpoints, they will be drawn most strongly to the common part, that of faith in Jesus, our Savior & God.)
Wow, I guess I got somewhat off-topic.....