Wikipedia has a good, in depth article about the sad phenomenon of family estrangement, which is related to shunning or ostracism. Family members who have been estranged (ostracized or scapegoated) are likely to develop PTSD and have dismally low self-esteem.
Family estrangement occurs for a number of reasons, and is most common in societies that value individualism over the family, tribe, or community, so it’s more common in the United States than in other countries. It’s also my personal opinion that it’s more common in upper middle class families who value material and financial success over loving relationships. An adult child who fails to toe the line and make the family “look good” becomes an embarrassment to the family’s upwardly mobile aspirations, and becomes the scapegoat or is even rejected from the family. They are also likely to be disowned. The ostracized adult child, lacking financial and emotional support and a healthy sense of self worth (because nothing is more devastating to a person’s sense of self esteem than being rejected by one’s own family), often falls into poverty, illness, or mental illness, further shaming the “perfect” family.
The sense of shame of having been rejected by the people who are supposed to love you unconditionally is emotionally, spiritually, and even physically devastating. It’s the worst kind of soul murder. To make matters worse, it’s often the “truth teller” (the one who sees through the toxic family dynamics) or the most sensitive or vulnerable child who is shunned in this way. The scapegoated or ostracized adult child is then blamed for their “failures” and told they brought their hard luck on themselves.
Cluster B personality disorders are very common in families where members become estranged, scapegoated or ostracized, because people with these disorders tend to lack empathy, which is the glue that holds families, tribes and societies together. Substance abuse is also a common factor and may be co-morbid with Cluster B disorders (substance abuse being a very common but maladaptive coping tool among people with these disorders).