Schizothymia is a temperament related to schizophrenia in a way analogous to cyclothymia's relationship with bipolar disorder.
[1] Schizothymia was proposed by German psychiatrist Ernst Kretschmer in the early 20th-century when examining body types of schizophrenic patients.
Schizothymia is defined by reduced affect display, a high degree of introversion, limited social cognition, and withdrawing from social relations generally.
Nevertheless, individuals with such personality traits may achieve relatively affable social relations and a measure of affectivity situationally.
As a kind of temperament, schizothymic personality traits are thought to be innate rather than the result of socialization or a lack thereof (Nature versus Nurture).