Hair color won't change a personality, its up to the individual. However, I do believe some blondes believe they have to live up to that stereotype to fit in so that creates a more noticeable differentiation between blondes and others because they are trying harder to have fun so they actually do end up having more fun.
It has been scientifically proven without a reasonable doubt that blondes do, in fact, have more fun. It may not be fair, but it's true. Non-blondes who dye their hair have 50% more fun. Getting blonde highlights will get you 10% more fun. Remaining a non-blonde results in more Saturday nights home alone.