At a fundamental level, humans think about social groups in terms of "us" vs "them," or the groups that "I am in" (in-groups) and those that "I am not in" (out-groups). Members and markers of an in-group are often favored and those of an out-group are often disparaged. Individuals may resist adopting a technology if it is associated with an out-group, and the technology itself may be a powerful marker in identifying group membership.This seems obvious, but it's worth keeping at the forefront when designing for or interacting with a particular group. Group markers can include the language, patterns of speech and writing, colloquialisms, world-perspectives (religion, politics) and all the artifacts that may be associated with the group (hair, music, transportation, technology devices). Getting too many wrong and you can isolate members of the group you are trying to reach.
Once, I misjudged the marker of a group by a long shot. I was fairly new to managing online groups of any size and I had a group of volunteers helping out. One night, I wanted to talk to two (they had just handled a pretty sticky conflict resolution issue and I was all hot to get a report), but blew past two others and asked to be left in private. I should mention at this point that this was in the WorldsAway virtual environment so there was a physical presence. The social marker that had developed among my volunteers was to always stop, take a moment to say hello and let each other know what they were currently doing. Because I sped past two without a word and asked for privacy without explaining why, I had behaved as an outsider and undermined some of the trust they had in me. Well, I wound up spending several hours late that night sorting things out, apologizing and immediately changed my behavior to include writing markers (which included a *lot* of smilies and gestures that I was not used to using).
Luckily, this lesson has stuck and now, working with parents, I've learned that formal language is the language of the school administrations, lawyers, and officials--definitely an out-group. I've dropped formal language in all my communications with parents on our boards. I make sure that I participate in group congatulations (births, school placements, child successes) because it's a behavior that marks the in-group. On the other hand, I use very formal (but not disparaging) language when I am writing to someone so blatantly advertising or antagonizing others to establish they are not welcome.