Don't Smile

I am not sure I agree but here comes another indicator of how class differences are manifested and, to some extent perpetuated. In a recent article Michael Kraus and Dacner Keltner describe different body language tendencies that are correlated with class. Here is part of their summary (the link above is to a short article about the article, not the original)

"Informed by recent advances in person-perception research,
and theoretical analyses of resource dependence and power, we
examined how SES is signaled in a face-to-face interaction. Our
first prediction was supported. SES was reliably associated with
a set of nonverbal cues: Upper-SES individuals exhibited more
disengagement and less engagement during a get-acquainted
interaction than did lower-SES individuals. Our second prediction
was also supported. Naive observers reached consensus
and identified participants’ family income, maternal education,
and subjective SES with greater-than-chance accuracy, despite
being exposed only to participants’ behavior during the get acquainted
interactions. Finally, these naive observers based
their judgments of targets’ SES—and rightly so—on targets’
disengagement- and engagement-related nonverbal behavior.
This study is the first to reveal relations between SES and social
engagement, and it is the first to show that SES can be readily
‘‘thin sliced’’ by naive observers."

What this means is that upper social class people have learned to signal their elite status by seeming to be disengaged, even bored, by others. This is especially true when getting acquainted because relative status has yet to be established. The authors suggest that the difference in behavior is an indicator that one is of high enough status that no approval of others is necessary. I'd say this reflects what I have described before as playing it close to the vest and revealing no emotions. Smile and nod too much and someone may think you are from a lower class. Be stuffy, and you are golden!