Interesting... I color my hair like every three-six months.. I've been blonde, red,brown,black,purple and many more.. (I am currently on brown-blonde ombre and plan to have it to gray ombre next month) Does that mean i got multiple personalities? HAHAHAHA
Maybe there's also an article regarding haircut connecting to personality too..
Statistically there is bound to be more of one personality than another with the same hair color. However black hair and brown hair may both be mostly estj (for example). So I don't think this idea is worthwhile.