A biography is a history of an individual but it often contains information about the individual's family.
Biographies can complicate research.
A biography is written by someone else other than the subject of the biography. It may include details based on memory and legend. It becomes more of a memorial than a document based only on the facts as they may have presented themselves. Add to that, any effort to change, hide or dilute parts of the history that the family or the person themselves may be ashamed of and the biography becomes part fiction instead of pure fact. Some biographies, like those included in many county history books, were considered Vanity articles.