This seems unnecessarily pedantic given the harmlessness of cross-cultural pollination but I'll take the question in good faith.

Obviously all cultural practices are necessarily adopted from individuals, groups, and other cultures. What I mean is that some cultures have practices that differ from the ones that are commonplace in the ones you may have grown up in or currently live within. I'm asking about those practices, the ones that aren't necessarily homegrown or common in your own life.

Seconding everything in this comment. I jumped from digg to reddit during the HDKEY scandal, so 16+ years as well. I remember feeling unsettled as Reddit moved into the eternal September of the later years

This rocks. Thanks for building such a useful tool!