Quote from the book "Разум в огне. Месяц моего безумия"

Not only did I believe that my family members were turning into other people, which is an aspect of paranoid hallucinations, but I also insisted that my father was an imposter. That delusion has a more specific name, Capgras syndrome, which a French psychiatrist, Joseph Capgras, first described in 1923 when he encountered a woman who believed that her husband had become a “double.”12 For years, psychiatrists believed this syndrome was an outgrowth of schizophrenia or other types of mental illnesses, but more recently, doctors have also ascribed it to neurobiological causes, including brain lesions.13 One study revealed that Capgras delusions might emerge from structural and circuitry complications in the brain, such as when the parts of the brain responsible for our interpretations of what we see (“hey, that man with dark hair about 5’10”, 190 pounds looks like my dad”) don’t match up with our emotional understanding (“that’s my dad, he raised me”). It’s a little like déjà vu, when we feel a strong sense of intimacy and familiarity but it’s not connected to anything we actually have experienced before. When these mismatches occur, the brain tries to make sense of the emotional incongruity by creating an elaborate, paranoid fantasy (“that looks like my dad, but I don’t feel like he’s my dad, so he must be an imposter”) that seems to come straight out of The Invasion of the Body Snatchers.