Psychologist: Birth-order effects, the alleged effects of when one was born relative to the births of siblings, have not been detected in studies of adult personality that use standard personality tests  However, they have been detected in birth-order studies that are based on parents' and siblings' reports of the subjects' personalities
All of these birth-order studies, taken together, show that birth order has no lasting effect on personality; instead, birth order affects merely how a sibling' s behavior is perceived
Standard personality tests will detect at least some birth-order effects on personality, if those effects exist.