Although superficial, this article suggests that while some national or gender stereotypes have a basis in reality, others do not.
In Robert McCrae's most recent study he asked people to assess not their own personality, but a "typical" member of their community. The stereotypes were certainly there: Germans rated themselves as highly conscientiousness; Australians considered themselves to be extrovert, and Canadians thought themselves to be more agreeable than most. But these projections of stereotype had more or less no relationship with the actual personality profile of average citizens of each country.It would be interesting to read something more complete about the U.S. than "Americans were similar to Canadians".... The original article is available online, but it doesn't fill in many of the gaps.
Germans rate themselves as highly conscientiousness but they score just about the same on this trait as Turks, who consider themselves to be rather unreliable and lazy. Puerto Ricans consider themselves highly extrovert but they are apparently no more so than the French Swiss who consider themselves introverted. These results indicate that such perceptions are social constructs, based on hearsay and prejudice.