There are various apparent mysteries of female cosmetics
. One of the more obscure is why women dye their hair blonde
The reason for this is fairly obvious and it involves Youth. From a biological perspective youth is a highly desirable property and, since many women's hair grow darker as they get older, lightening your hair increases your desirability.
Of course, this could all be subconscious and tied up in your genes but it's all from the same motive that makes women pluck their eyebrows and remove body hair and generally make them look like they're fresh through puberty.