Although the cause of antisocial personality disorder is unclear, some people do appear to have a genetic vulnerability. For example, twin and adoption studies indicate that biological relatives of those with antisocial personality disorder:
Twin and adoption studies indicate that biological relatives of those with antisocial personality disorder are at increased risk for antisocial behavior
Twin and adoption studies allow one to tease apart the effects of genes and environments
Adoption studies compare whether an adopted child is more similar behaviorally to the child's adoptive parents (with whom environments, but not genes, are shared) or to the child's biological parents (with whom genes, but not environments, are shared)
Twin and adoption techniques have been used to demonstrate that nearly all behavior is under some degree of genetic influence
