How is schizotypal personality disorder formed and manifested?

If you believe of modern psychiatry, then the main manifestations of schizotypal personality disorder are non-standard (extraordinary) behavior and at the same time stereotypical thinking. It is believed that the disorder is characterized by prevailing introspection. It follows that introversion, weak social ties, the absence of a large number of trusting relationships are companions of this disorder.
Also, signs of schizotypal personality disorder, previously called latent, sanatorium, mild, etc. - why, by the way, this disorder was called occult schizophrenia.
This disorder can be easily confused with neurosis, depression, paranoia. And, in principle, diagnostics in psychiatry is a thankless task, since there are no clear boundaries. Most people can be summed up under the description of signs of disease and deviations to one degree or another. Does this mean that the state and behavior of a primitive representative of our species is taken as the basis for the concept of norm? Scientists decide. We, ignoramuses and self-taught, can only wait for the conclusion of authoritative experts.
Regarding the first part of the question, Love, I note that at the moment I do not know the evidence (scientifically substantiated) base of hypotheses about the nature of the occurrence of any mental disorder, as well as and cases of successful treatment without relapses in this area of ​​medicine.
But there is one interesting version. Its essence is that about eighty percent of the probability of manifestation of any mental disorder is heredity, twelve - the social environment and only eight - family relationships and upbringing.
Only many factors that make up the way of life are not taken into account.

If you are very interested in this topic, read Ronald Lang, Samokhvalov, Krachmer.

The basis of personality is character, which is determined by heredity (to a greater extent) and under the influence of external factors (social environment, upbringing).

There are several types of premorbid personality type, which is under the influence of long-term psycho-traumatic factors or even organic pathology of the brain can transform into a certain personality disorder.

For people with a schizoid personality type, isolation is characteristic, which is combined with external coldness, restraint. These people are not able to experience others. There is also a lack of intuition in terms of interpersonal relationships. These people usually live in an inner world.

In the presence of predisposing factors, these personality traits are aggravated: for people with schizotypal personality disorder (in addition to the above signs), unreasonable outbursts of anger, fits of rage, mood lability, obsessive thoughts and ideas are characteristic, stereotypical thinking.