Here is an interesting article about this argument.
In a groundbreaking study recently published by the Mayo Clinic and Johns Hopkins, scientists have discovered that while blondes have nearly 380% more sex (of all kinds) than other color haired people, they do not, in fact, have more fun.
The Mayo Clinic / Johns Hopkins report broke down “fun” along sexual lines, as that is commonly what blondes are referring to when they speak of “fun.” They discovered that blondes were ten times more likely to consent to giving fellatio than were their brunette, redhead, or dye-headed sisters ... They were seven times more likely to engage in “doggy-style” sex, and five times as likely to do it in some kind of spectacular manner, such as in a public place or swinging from a specially-built trapeze.
Read the article here.
I've never felt the need to dye my hair. Do I have fun? Hmm...