How do you explain extreme reserve in people?

Usually these are people for whom extreme reserve has been modeled by parents, siblings, aunts, uncles, neighbors, fellow church members. Any show of emotion is seen as weak and "lower cl", although girls and women are allowed to show some emotion as "feminine". Extreme reserve is seen as "cly" and "polite", even "respectable". Generally reserve can be relaxed only during periods of drinking alcohol or sometimes in sports. The ideal in such a society is the businessman, the industrialist, sometimes the physician or surgeon. These are societies where only extroversion is admired, and introversion is not. That is, the allowable interest must be on facts, things, sensory data, and its correlates in money, possessions, clothes, cars, boats, homes and so on. There is very little perceived value in thinking except to further one's wealth or personal status, or in feelings, or ysis, or anything related to art and creativity. Generally these people learn to feel uncomfortable physically and ually, unless in male pursuits of visceral uality, often illicit. Women are taught uality is only for making babies and for attracting prestigious boyfriends and husbands. Otherwise, any libido left over should be discharged in tennis, golf, horseback riding, or maybe gardening and the like. Extremely reserved people maintain a psychic barrier between themselves and the rest of life and people, or try to. They want to regard themselves as "special", "entitled". Typically they acquire some wealth and learn with disappointment it does not alone make them "better" than others in anyone's eyes or even their own. Hence a sense of extreme reserve does serves that purpose, especially when undertaken as a group of reserved families in ociation with each other, e.g., living in an upscale neighborhood, belonging to the same country club, belonging to the same Protestant church.