Do you really think it ' s possible for someone to be a remorseless murderer without them having a mental disorder ? A mental disorder isn ' t just a physical thing that one can detect with a physical test it is determined by analyzing a person ' s thoughts and behaviors , and the disorder an individual is diagnosed with is simply a description of those thoughts and behaviors . Antisocial personality disorder is defined as a personality disorder , characterized by a pervasive pattern of disregard for , or violation of , the rights of others . A person with this disorder acts rationally in accordance with their own selfinterest , but rationality has little to do with mental disorders . They have a mental disorder due to their lack of concern about other people ' s interests . If someone murders their own children and thinks it was a fine thing to do , then they must have a mental disorder to think that is the case , and it is likely something similar to antisocial personality disorder . If they didn ' t have a mental disorder , then they would , by definition , function normally and not think that murdering your children is OK .